Researcher Profile and Settings

Affiliation

• Faculty of Fisheries Sciences　Marine Bioresource and Environmental Science　Marine Environment and Resource Sensing

Job Title

• Professor

Degree

• Ph.D.（Hokkaido University）

Contact information

• mukaifish.hokudai.ac.jp

Research funding number

• 60209971

J-Global ID

• 200901066628359210

Research Interests

• ターゲットストレングス   計量魚群探知機   音響資源調査   生体密度   魚群探知機   音響反射   プランクトン   生体内音速   水中音響   海洋探査   水中音響技術   ローシー   海洋資源   音速   水中映像   体密度   動物プランクトン   体内通過音速   タイムオブフライト法   超音波散乱特性   海洋生態   カイアシ類   雌雄判別   オキアミ   スルメイカ   可視化   海洋生態系   FMTネット   デッドゾーン   ROV   水産音響   Acoustic Information   Fisheries Acoustics   

Research Areas

• Environmental science/Agricultural science / Environmental dynamics
• Life sciences / Aquaculture

Educational Organization

•  Bachelor's degree program　School of Fisheries Sciences
•  Master's degree program　Graduate School of Fisheries Sciences
•  Doctoral (PhD) degree program　Graduate School of Fisheries Sciences

Academic & Professional Experience

• 2016/04 - Today Hokkaido University Faculty of Fisheries Sciences Professor
• 2014 Hokkaido University
• 2005 - 水産科学研究院助教授（海洋生物資源科学部門海洋資源計測学分野） 助教授
• 2005 - Associate Professor
• 2000 - 水産科学研究科助教授（環境生物資源科学専攻資源計測学講座） 助教授
• 2000 - Associate Professor
• 1995 - 同助教授（水産学部海洋生産システム学科生産システム設計学講座) 助教授
• 1995 - Associate Professor
• 1988 - 北海道大学助手（水産学部漁業学科漁業測器学講座） 助手
• 1988 - Research Associate

Education

•        - 1986  Hokkaido University  School of Fisheries Sciences
•        - 1986  Hokkaido University  Faculty of Fisheries

Association Memberships

• Asian Fisheries Acoustics Society   日本水産学会   海洋調査技術学会   海洋音響学会   アメリカ音響学会   

Research Activities

Published Papers

• Abundance and potential sources of floating polystyrene foam macro- and microplastics around Japan

  Mao Kuroda, Atsuhiko Isobe, Keiichi Uchida, Tadashi Tokai, Toshihide Kitakado, Miho Yoshitake, Yoshinori Miyamoto, Tohru Mukai, Keiri Imai, Kenichi Shimizu, Mitsuharu Yagi, Takahisa Mituhasi, Akimasa Habano

  Science of The Total Environment 925 171421 - 171421 0048-9697 2024/05 [Refereed]
  
• Broadband target strength of arabesque greenling, Pacific sand lance, and pointhead flounder

  NAIZHENG YAN, Tohru Mukai, Kohei Hasegawa, Jun Yamamoto, Yoshiaki Fukuda

  ICES Journal of Marine Science 1054-3139 2023/12/12 [Refereed]
   

  Abstract Measurement of target strength (TS) is important for estimating the abundance of species using fisheries acoustics. However, most researchers have only used a limited number of representative frequencies for acoustic measurements of fish without a swim bladder (bladderless fish). Here, we measured the broadband TS of three bladderless fish species, arabesque greenling (Pleurogrammus azonus), Pacific sand lance (Ammodytes personatus), and pointhead flounder (Cleisthenes pinetorum), using two broadband echosounders. TS measurements were conducted in a seawater tank over frequency ranges of 45–90 and 80–120 kHz using a tether method. Higher TS and directivity were observed at higher frequencies than at lower frequencies for pointhead flounder and arabesque greenling. However, the TS for Pacific sand lance was relatively flat over the measured frequency spectra. Additionally, the TS of pointhead flounder and Pacific sand lance could be expressed as a function of body length and the TS of arabesque greenling could be expressed as a function of body length and frequency, which could be used in fish species discriminations and size estimations.
• Estimating the Catch Efficiency of a Framed Midwater Trawl under Different Sampling Conditions Using an Acoustic Method

  Zhen Lu, TOHRU MUKAI, Yasuzumi Fujimori, Kohji Iida

  Journal of Marine Science and Engineering 2023/11/29
• Measurements and Theoretical Model Simulation of Target Strength of Pacific Chub Mackerel for Use in a Quantitative Sonar

  YAN Naizheng, 向井徹, 長谷川浩平, 飯田浩二, 鶴田直剛

  海洋音響学会誌 50 (4) 0916-5835 2023 [Refereed]
  
• Standardization and database development of marine plastic survey in the offshore areas around Japan

  Keiichi Uchida, Ryuichi Hagita, Tohru Mukai, Keiri Imai, Kenichi Shimizu, Mitsuharu Yagi, Yuichi Yamanaka, Takahisa Mituhasi, Atsuhiko Isobe, Mao Kuroda

  Nippon Suisan Gakkaishi (Japanese Edition) 89 (5) 394 - 397 0021-5392 2023
• Two species of seabirds foraged in contrasting marine habitats across the cold-water belt along the coast of northern Hokkaido in the southwestern Okhotsk Sea

  Bungo Nishizawa, Jumpei Okado, Yoko Mitani, Tomohiro Nakamura, Atsushi Yamaguchi, Tohru Mukai, Yutaka Watanuki

  Fisheries Science 88 (1) 109 - 118 0919-9268 2022/01 [Refereed]
   

  To understand the environmental factors affecting the density of foraging seabirds across the cold-water belt in the southwestern Okhotsk Sea, we conducted a 1-day (180-km transect length) shipboard seabird survey off the northeastern coast of Hokkaido during summer in 2019, along with acoustic observations of potential prey (zooplankton and fish) biomass, thermosalinograph measurements, and CTD observations. Planktivorous short-tailed shearwaters Ardenna tenuirostris (66% of total seabirds) and piscivorous rhinoceros auklets Cerorhinca monocerata (28%) were predominant, but foraged in contrasting habitats. A large foraging flock of shearwaters was observed in the cold-water belt zone, including its front with coastal Soya Warm Current Water and the offshore Fresh Surface Okhotsk Sea Water, where surface chlorophyll a concentrations were the highest but not related to their prey (zooplankton) biomass at any spatial scale between 4.6 and 9.2 km. In contrast, the density of auklets was high in the coastal Soya Warm Current Water, where the acoustically determined fish biomass was large, and showed a positive relationship with the fish biomass especially in the lower layer (29–104 m depth) at any spatial scale. This species-specific difference in response to prey biomass might be related to prey-searching behaviors; i.e., rhinoceros auklets search prey underwater visually, but short-tailed shearwater can use both visual and olfactory cues to locate zooplankton patches from the air.
• A multilevel dataset of microplastic abundance in the world’s upper ocean and the Laurentian Great Lakes

  Atsuhiko Isobe, Takafumi Azuma, Muhammad Reza Cordova, Andrés Cózar, Francois Galgani, Ryuichi Hagita, La Daana Kanhai, Keiri Imai, Shinsuke Iwasaki, Shin’ichro Kako, Nikolai Kozlovskii, Amy L. Lusher, Sherri A. Mason, Yutaka Michida, Takahisa Mituhasi, Yasuhiro Morii, Tohru Mukai, Anna Popova, Kenichi Shimizu, Tadashi Tokai, Keiichi Uchida, Mitsuharu Yagi, Weiwei Zhang

  Microplastics and Nanoplastics 1 (1) 1 - 16 2021/09 [Refereed]
   

  Abstract A total of 8218 pelagic microplastic samples from the world’s oceans were synthesized to create a dataset composed of raw, calibrated, processed, and gridded data which are made available to the public. The raw microplastic abundance data were obtained by different research projects using surface net tows or continuous seawater intake. Fibrous microplastics were removed from the calibrated dataset. Microplastic abundance which fluctuates due to vertical mixing under different oceanic conditions was standardized. An optimum interpolation method was used to create the gridded data; in total, there were 24.4 trillion pieces (8.2 × 10⁴ ~ 57.8 × 10⁴ tons) of microplastics in the world’s upper oceans.
• The Annual Variability of Density and Sound-Speed Contrasts and Their Influence on Target Strength of Euphausia pacifica off the Coast of Kushiro, Hokkaido

  FUKUDA Yoshiaki, MUKAI Tohru, SAWADA Kouichi, MATSUURA Tomohiko

  The Journal of the Marine Acoustics Society of Japan 特定非営利活動法人 海洋音響学会 48 (1) 1 - 14 0916-5835 2021 [Refereed]
   

  We measured the density and sound-speed contrasts of Euphausia pacifica off the coast of Kushiro, Hokkaido from 2010 to 2014. These experiments were carried out in May–June (2010) and September–October (between 2011 to 2014). The density contrast was measured using the density bottle method, and the sound-speed contrast was measured by the time-of-flight method using a T-tube in each year. There were no significant differences in the mean values of the measured density and sound-speed contrasts by year, and the mean density and sound-speed contrasts through all years were 1.043 and 1.040, respectively. We also estimated the dorsal aspect mean target strength (TS) using the distorted-wave Born approximation-based deformed-cylinder model (DWBA model), finding that the relationships between total length (TL) [mm] and the mean TS at each frequency were TS=60.9 log TL−177.2 at 38 kHz, TS=57.2 logTL−163.6 at 70 kHz, TS=52.9 log TL−151.5 at 120 kHz, and TS=44.2 log TL−135.5 at 200 kHz. Since there was less annual variability in the density and sound-speed contrasts during the period examined in the present study, we recommend that the acoustic survey be conducted in September or October.

• In situ broadband acoustic measurements of age-0 walleye pollock and pointhead flounder in funka bay, hokkaido, japan

  Kohei Hasegawa, Naizheng Yan, Tohru Mukai

  Journal of Marine Science and Technology (Taiwan) 29 (2) 135 - 145 1023-2796 2021 [Refereed]
   

  Measurements of the broadband acoustic backscattering from fish should improve acoustic discrimination between species. The pulse compression processing of broadband systems can be used tomeasure acoustic backscattering with high range resolution and improve signal-to-noise ratio. This may increase opportunities for in situ target strength (TS) measurements, the preferredmethod of collecting TS data. To evaluate the availability of TS spectra for acoustic discrimination, three Simrad EK80 wideband transceivers and split-beam transducers of 70, 120, and 200 kHz were used to collect in situ frequency responses of TS from age-0 juvenile walleye pollock and pointhead flounder, a swim-bladderless flat-fish, distributed in and around Funka Bay, Hokkaido, Japan. The single echoes were extracted frombackscattering data, and the TS spectra of the two species were obtained. However, processing of the broadband acoustic data is under discussion. To ensure the reliability of our data, the TS spectra of standard targets were also calculated. The measured TS spectra of the standard targets were close to the theoretical TS spectra. The individual TS spectra of two species included complex frequency response; however, the mean TS spectrum was relatively stable. The different characteristics of the frequency responses observed for the two species were in good agreement with reported observations. The results available for the acoustic discrimination were similar to the multi-frequencymethod, which uses two or more single frequencies. The rawTS spectra should aid in not only discriminating between species but also estimating the size of the fish.
• Estimating the zooplankton sampling efficiencies of a framed midwater trawl and a ring net using an acoustic method

  Zhen Lu, Tohru Mukai, Yasuzumi Fujimori, Kohji Iida

  Journal of Marine Science and Technology (Taiwan) 29 (2) 185 - 196 1023-2796 2021 [Refereed]
   

  It is well known that there is bias using different sampling gear, such as a framed midwater trawl (FMT) and a ring net, when measuring the density and length distribution of target species. This limit is characterized by the sampling efficiency of the gear. Acoustic monitoring can be used to determine the sampling efficiencies of this gear, as its noninvasive, wide-range sweeps provide more reliable estimates of absolute abundance of the target species. The density measured by the gear can then be standardized by multiplying the initial density measurement by the derived sampling efficiency. In this study, we compared the estimated densities of the dominant zooplankton in the sound scattering layer (SSL) from acoustic monitoring to the densities of the same species measured using the FMT and ring net. The respective sampling efficiencies of this gear for zooplankton categories was then determined using linear regression models. For small Euphausiidae and Copepoda, the sampling efficiency of ring net was higher than that of FMT. In contrast, the ring net was less effective than FMT for large Euphausiidae. These results highlight that the entering and retention rates of the species depend on the type and characteristics of the survey gear, as well as the size and swimming ability of the target species.
• Timing of spring sea-ice retreat and summer seabird-prey associations in the northern Bering Sea

  Bungo Nishizawa, Nodoka Yamada, Haruka Hayashi, Charlie Wright, Kathy Kuletz, Hiromichi Ueno, Tohru Mukai, Atsushi Yamaguchi, Yutaka Watanuki

  Deep-Sea Research Part II: Topical Studies in Oceanography 181-182 0967-0645 2020/12 [Refereed]
   

  To understand the effect of an unusually early sea-ice retreat in the northern Bering Sea in the spring of 2018 on the marine ecosystem of the northern Bering Sea, we compared at-sea observations of seabird density and acoustic observations of prey (fish and zooplankton) biomass during shipboard surveys around St. Lawrence Island in the summers of 2017 and 2018. Densities of foraging seabirds in 2018 (piscivorous divers: 4.7 birds km−2, planktivorous divers: 5.1, shearwaters: 0.7, surface feeders: 6.6) were lower than those in 2017 (piscivorous divers: 14.7 birds km−2, planktivorous divers: 10.3, shearwaters: 11.9, surface feeders:11.9). Acoustically-determined prey biomass in 2018 (fish: 6.4 m2nmi−2, zooplankton: 2.3) was also lower than in 2017 (fish: 18.4 m2nmi−2, zooplankton: 5.5). Similarly, biomass of macrozooplankton (amphipods, euphausiids, Neocalanus spp. and Calanus marshallae) sampled using bongo nets was smaller in 2018. At scales of 5–30 km, correlations between the seabird density and prey biomass were weaker (−0.2–0.3 of Pearson's r) in 2018 than those in 2017 (0.4–0.9) for all seabirds except planktivorous divers. We suggest that the lack of sea ice, and the resulting lack of ice-edge phytoplankton blooms, may weaken trophic linkages by causing a low biomass of secondary consumers and hence a reduced density of seabirds.
• The current state of marine debris on the seafloor in offshore area around Japan

  Mao Kuroda, Keiichi Uchida, Tadashi Tokai, Yoshinori Miyamoto, Tohru Mukai, Keiri Imai, Kenichi Shimizu, Mitsuharu Yagi, Yuichi Yamanaka, Takahisa Mituhashi

  Marine Pollution Bulletin 161 (Pt A) 111670 - 111670 0025-326X 2020/12 [Refereed]
   

  Marine debris on the seafloor has not been thoroughly investigated, and there is little information compared to other types of marine debris. We conducted bottom trawl surveys to determine the present situation of marine debris on the seafloor in offshore areas around Japan. The survey was conducted in three sea areas with different characteristics. As a result, it was found that the amount of marine debris in submarine canyons (2926.1 items/km2) was higher than on the continental shelf. It was revealed that most marine debris on the seafloor is comprised of plastic products, and that debris on the seafloor retains its condition for a long time (over 30 years) without deterioration. In addition, the type of marine debris is affected by the industries operating in each area. Continuing to investigate marine debris on the seafloor in more areas will contribute to solving the problem of marine debris.
• Acoustic discrimination between juvenile walleye pollock and pointhead flounder

  Naizheng Yan, Tohru Mukai, Jun Yamamoto, Kohei Hasegawa

  Fisheries Research 105434 - 105434 2020/04 [Refereed][Not invited]
  
• Observation and model experiments on an internal-wave packet accompanied by streak bands over the sill topography of Tsugaru Strait

  Takuya Yamaguchi, Yutaka Isoda, Umihiko Itoh, Tohru Mukai, Naoto Kobayashi

  Oceanography in Japan 日本海洋学会 29 (3) 71 - 90 0916-8362 2020 [Refereed][Not invited]
   

  The Synthetic Aperture Radar (SAR) around the western entrance of the Tsugaru Strait has yielded well-defined images of an internal-wave packet accompanied by two or three surface-streaks (surface convergence within the same water mass), which is active during the stratified season, and whose wavelength is in the order of several hundred meters. Most of the waves in the packet were observed near the topographically shallow parts of the sill. Temporal changes were repeatedly observed in the internal waves confined to the sill using a high-frequency echosounder profiler within one-day in the summer 2017. The acoustic images suggest that a wave packet of extraordinary amplitude (> 150 m) has developed transiently around the downstream side of the sill at the ascending passage flow. This wave packet consists of two or three successive streak bands, with very disturbed sea surface conditions overlying wave troughs, i.e., strong downwelling areas. The dynamics of such waves developing over the sill is studied through a fully nonlinear nonhydrostatic numerical model. The vertical fluid stratification and temporal change of the barotropic passage flow were adjusted to approximate our observation conditions. The results suggest that the wave packet is effectively amplified near the downstream side of the sill, where the Froude number becomes a critical point, because upstream propagating waves on the sill slope stagnate and overlap efficiently. In this dynamical process, however, even if the wave grows to large amplitude, it does not form a well-organized solitary wave, but is rather scattered due to the strong dispersion of waves.

• Vertical distributions of walleye pollock Gadus chalcogrammus and euphausiids on the continental shelf of southern Okhotsk Sea, off the coast of Hokkaido, by using a quantitative echosounder

  水上 卓哉, 板谷 和彦, 向井 徹, 飯田 浩二

  北海道水産試験場研究報告 = Scientific reports of Hokkaido Fisheries Research Institutes 北海道立総合研究機構水産研究本部 (96) 41 - 52 2185-3290 2019/09
• Variation of Zooplankton Mean Volume Backscattering Strength from Moored and Mobile ADCP Instruments for Diel Vertical Migration Observation

  Angga Dwinovantyo, Henry M. Manik, Tri Prartono, Susilohadi Susilohadi, Tohru Mukai

  Applied Sciences 9 (9) 1851 - 1851 2019/05/06 [Refereed][Not invited]
  
• Estimating the Catch Efficiency of a Framed Midwater Trawl for Juvenile Walleye Pollock (Gadus Chalcogrammus) Using an Acoustic Method

  LU Zhen, 向井徹, 藤森康澄, 飯田浩二

  水産工学 55 (2) 135‐144  0916-7617 2018/11 [Refereed][Not invited]
  
• Measurement of the volume-backscattering spectrum from an aggregation of Antarctic krill and inference of their length-frequency distribution

  Kazuo Amakasu, Tohru Mukai, Masato Moteki

  Polar Science 12 79 - 87 1873-9652 2017/06 [Refereed][Not invited]
   

  Antarctic krill, Euphausia superba, were observed using a broadband echosounder and their length density distribution was inferred from the echo data through a least square inversion. The observation was conducted in the Indian Ocean sector of the Southern Ocean in January 2014. The transmit signal was a 10-ms linear frequency-modulated signal with a frequency sweep of 20-200 kHz. A large aggregation of Antarctic krill was observed at a sampling station over the continental shelf. The volume-backscattering strengths in the frequency range of 85-187 kHz were determined from the observed echoes. In addition, the signal-to-noise ratio at each frequency was estimated and the measured volume-backscattering strengths were evaluated before inversion for accurate inferences. In this inversion, Antarctic krill were modeled as prolate spheroids and the target strengths were predicted by the distorted-wave Born approximation. The acoustically inferred mean length was in good agreement with the mode length determined by a net sampling performed immediately after the echo sampling. Also, the acoustically inferred length-frequency distribution was in reasonable agreement with the determined one from the net samples. (C) 2017 Elsevier B.V. and NIPR. All rights reserved.
• Comparison of the Effectiveness of Acoustic Measurements Between 2 Frequencies（ 38kHz, 120kHz） for Monitoring of 0+ Japanese Jack Mackerel, Trachurus Japonicus, off the Tottori Coast in the Sea of Japan

  HIROSE Miyuki, SHIMURA Tsuyoshi, MUKAI Toru

  Journal of Fisheries Engineering 日本水産工学会 54 (3) 163 - 172 0916-7617 2017 [Refereed][Not invited]
   

  The aim of this study was to compare the effectiveness of acoustic measurements between twofrequencies （38 kHz, 120 kHz） for estimations of the distribution and abundance of 0+ Japanese jackmackerel, Trachurus japonicus, off the Tottori coast in the Sea of Japan. The vessel Tottori Maru No. 1collected acoustic data off the coast of Tottori at frequencies of 38 and 120 kHz （KFC3000）. Samplingwas also conducted using a midwater trawl net and an 80-cm ring net. A sound scattering layer wasfound to overlay the echo of the Japanese jack mackerel when sampled at 38 kHz, presenting an inherentproblem to acoustic studies at this frequency. However, signals from Japanese jack mackerel could beidentified on an echogram at 120 kHz. Also, the density of one individual per m3 （n） of Japanese jackmackerel, determined using the trawl net, was positively correlated with the value of the volumebackscattering strength（ SV） at 120 kHz（Mean SV120 kHz ＝ 10 log n – 58.01（ r ＝ 0.68））. Therefore, it ispossible to estimate the distribution and abundance of 0+ Japanese jack mackerel more accurately using120 kHz data.
• Acoustic identification of krill and copepods using frequency differences of volume backscattering strength around Funka Bay, Hokkaido, Japan

  KIM EUNHO, MUKAI TOHRU, IIDA KOHJI

  NIPPON SUISAN GAKKAISHI 日本水産學會 82 (4) 587 - 600 0021-5392 2016 [Refereed][Not invited]
   

   In and around Funka Bay in southwest Hokkaido, Japan, krill and copepods are the dominant species of zooplankton. In this area, they are important prey for walleye pollock Gadus chalcogrammus and other marine animals. In this study, we examined the possibility of identifying krill and copepods based on differences in volume backscattering strength at different frequencies. Acoustic surveys were conducted in and around Funka Bay in March 2012 aboard the T/S Ushio-maru using a Simrad EK60 quantitative echo sounder. The acoustic data were collected at 38, 120 and 200 kHz. Biological samples were collected by a ring net with vertical towing. To identify the krill and copepods, differences in volume backscattering strength at three frequencies were examined. Krill and copepods showed stronger response at 120 and 200 kHz than at 38 kHz. The results showed that the differences in volume backscattering strength between 120 and 200 kHz (ΔSV_{200-120 kHz}) were −1.5 to 1.3 dB for krill and 2.2-3.7 dB for copepods. Based on these differences between frequencies, we were able to identify krill and copepods.

• Classification of sound-scattering layers using swimming speed estimated by acoustic Doppler current profiler

  Kyounghoon Lee, Tohru Mukai, Dae-Jae Lee, Kohji Iida

  FISHERIES SCIENCE 80 (1) 1 - 11 0919-9268 2014/01 [Refereed][Not invited]
   

  There are various techniques for identifying fish species, including the multi-frequency method, in situ target strength characteristics, and digital image processing methods. Acoustic Doppler current profilers (ADCPs) are able to determine multiple current fields simultaneously and have been used to observe the swimming speed and behavior patterns of shoals of pelagic fish under natural conditions. In this study, we evaluated a classification method that can be used to determine the swimming velocity of both the sound-scattering layer and pelagic fish shoals using an ADCP (153.6 kHz) and a scientific echosounder (38, 200 kHz). To calculate the actual swimming speed of the fish shoals, the mean swimming velocity vectors of each stratified bin must be compared with the mean surrounding three-dimensional (3D) current velocity vectors. We found the average 3D swimming velocity of the sound-scattering layer to be characterized by a deviation of > 5.3 cm/s from the surrounding current field. The average 3D swimming velocity of Pacific saury Cololabis saira was calculated to be 91.3 cm/s, while that of lanternfish Diaphus theta was 28.1 cm/s. These swimming speeds correspond to 4.19- and 4.26-fold the body length, respectively. Thus, the use of ADCP swimming velocity data can be expected to be a valuable species identification method for various fishes distributed in a given survey area.
• Acoustic Characteristics of Nemopilema nomurai Depending on the Swimming Angle

  HIROSE Miyuki, MUKAI Tohru

  The Journal of the Marine Acoustics Society of Japan 特定非営利活動法人 海洋音響学会 41 (1) 1 - 11 0916-5835 2014 [Refereed][Not invited]
   

  Acoustic techniques are commonly used to study the distributions and abundances of fish and zooplankton, because these techniques can survey large areas relatively quickly. Recently, acoustic-scattering techniques such as echosounders have been applied to jellyfish monitoring. Several studies have examined the acoustic-scattering characteristics of Nemopilema nomurai, but the influence of changes in the swimming (swimming angle) of this jellyfish on target strength (TS) has yet to be determined. This information has important implications for estimations of the abundance of jellyfish. In this study, the TS of live jellyfish in a seawater tank was measured to clarify the relationship between TS and swimming angle. Both measured and modeled scattering patterns depended on the swimming angle, revealing that the TS was largest for the head-aspect (incident on the bell of the jellyfish: 0 degree) swimming angle, and 10 dB lower for the intermediate-aspect swimming angle. The reduced target strength (RTS) in the side-aspect angle (range, 20–160º) varied between −60 and −50 dB; there was good agreement between the estimated and measured TS values.
• Application of Multilayer Piezoelectric Actuators to Broadband Backscattering Measurements of Aquatic Animals

  AMAKASU KAZUO, MISHIMA YUKA, SASAKURA TOYOKI, MUKAI TOHRU, SAWADA KOUICHI

  海洋音響学会誌 40 (3) 126 - 137 0916-5835 2013/07 [Refereed][Not invited]
  
• Measurement of Fish School Backscattering Strength Directivity Using Omnidirectional Scanning Sonar

  TAKAHASHI Ryuzo, IIDA Kohji, MUKAI Tohru, NISHIMORI Yasushi

  The Journal of the Marine Acoustics Society of Japan 特定非営利活動法人 海洋音響学会 40 (3) 113 - 125 0916-5835 2013 [Refereed][Not invited]
   

  The horizontal acoustic backscattering strength of a fish school is an important factor for fisheries and for estimation of the size of a fish school using omnidirectional scanning sonar. However, the backscattering strength of a fish school is influenced by their behavior and orientation because the individual fish in the fish school have strong directivity of target strength. This paper discusses a method for estimating the directivity of the backscattering strength of the fish school by analyzing fish school behavior. Sonar data were collected by a purse seine fishing boat equipped with the quantitative scanning sonar FSV-30R in Barents Sea and on the Pacific coast of northern Japan. Swimming speed, swimming direction, volume backscattering strength (SV_{_SCH}), and the target strength of the fish school (NTS) were analyzed for several swimming fish schools. The results showed strong directivity in the backscattering strength at the direction perpendicular to the swimming course; this result is similar to that of the directivity of the target strength. The directivity varied in relation to the distribution of the orientation of the fish, resulting from both the swimming speed and the direction of the fish school. These findings will enable the estimation of fish school abundance more precisely.
• Measurement of Target Strength of Euphausia pacifica Using a High-Frequency Broadband Signal

  FUKUDA Yoshiaki, MUKAI Tohru, SAWADA Kouichi, IIDA Kohji

  The Journal of the Marine Acoustics Society of Japan 特定非営利活動法人 海洋音響学会 40 (3) 138 - 148 0916-5835 2013 [Refereed][Not invited]
   

  The target strength (TS) spectrum of a marine organism is a key factor in the target discrimination of that organism. In this study, the side-aspect TS spectrum of Euphausia pacifica was measured as a function of the incident angle of the ensonified wave in a seawater tank using a broadband transducer with a bandwidth of 300–700 kHz. The measurements were compared with the theoretical predictions by the distorted-wave Born approximation-based deformed-cylinder model (DWBA model). The TS pattern measurements were in good agreement with the DWBA model predictions for the main lobe but not with those for the side lobe. The measurements of the relationship between the normalized mean TS spectrum and the total length divided by wavelength ratio were in good agreement with model predictions.
• Characteristics of Three-dimensional Target Strength of Swim Bladdered Fish

  KURNIA Muhammad, IIDA Kohji, MUKAI Tohru

  海洋音響学会誌 海洋音響学会 39 (3) 93 - 102 0916-5835 2012/07 [Refereed][Not invited]
   

  We discuss the acoustic characteristics of the three-dimensional target strength (3DTS) of defrosted Japanese Jack mackerel and Chub mackerel. The target strength of fish in the whole aspect was measured in a tank by changing the horizontal incident angle from 0° to 360° by 1° steps and the pitch angle from 0° to 90° by 10° steps. Prior to measurement of TS, morphological parameters including swim bladder size and shape were measured by soft X-ray for theoretical estimation. The theoretical TS of fish were calculated using the prolate-spheroid model based on morphological parameters and were compared with the measured values. Results showed that both the maximum and the minimum TS were proportional to body length, and the directivity of the TS was strongly associated with its orientation. The TS of fish changed significantly with the changing yaw and pitch angle of the fish, but remained fairly constant as the roll angle of the fish changed. The maximum and minimum TS were found at the broadside and end-on aspects of the fish, respectively.
• Lateral target strength of Euphausia pacifica measured by a tethered method

  FUKUDA YOSHIAKI, MUKAI TOHRU, SAWADA KOUICHI, IIDA KOHJI

  NIPPON SUISAN GAKKAISHI 日本水産學會 78 (3) 388 - 398 0021-5392 2012/05/15 [Refereed][Not invited]
   

    Side-aspect target strengths (TS) of Euphausia pacifica (10.9∼19.6 mm in total length [TL], n=44) were measured as a function of the incident angle of the ensonified wave at 120 kHz and 200 kHz. These measurements were compared with the theoretical predictions by the Distorted-Wave Born Approximation-based deformed-cylinder model (DWBA model). The measurements agreed with the predictions. Dorsal-aspect TSs as a function of the incident angle of the ensonified wave were also predicted by taking the curvature of the body in their swimming condition into account. The relationship between the reduced maximum TS (TS_{cm, max}) in dorsal aspect by the DWBA model and the total length to wavelength ratio (TL/λ) was expressed by TS_{cm, max}=36.5 log TL/λ−91.4.
  
• Acoustic Characteristics of Nemopilema nomurai

  広瀬美由紀, HWANG Doojin, 向井徹

  海洋音響学会誌 海洋音響学会 39 (1) 34 - 38 0916-5835 2012/01 [Refereed][Not invited]
  
• Performance of laser optical plankton counter (LOPC) for in situ measurement of multispecies aggregation of zooplankton

  Yukiko Yamashita, Yasuzumi Fujimori, Toru Mukai, Susumu Shimizu

  Nippon Suisan Gakkaishi (Japanese Edition) 日本水産學會 78 (5) 903 - 912 0021-5392 2012 [Refereed][Not invited]
   

  The Laser Optical Plankton Counter (LOPC) has been used to evaluate abundance structure of micro-organisms like a zooplankton speedy. The sea experiments were conducted at twelve stations near Funka Bay, Hokkaido to examine the performance of the LOPC for in situ measurement of multispecies aggregation of zooplankton. The LOPC was mounted with ring net (80 cm mouth diameter) and towed vertically. Size and volume composition data of LOPC and net samples were compared each other. The particle size composition detected by the LOPC showed similar pattern with wet weight composition of copepods and amphipods in net samples. However, the ranges of equivalent spherical diameter of these species were overlapped. To measure in situ zooplankton community by species using LOPC, the measurement properties of each particle by specie should be identified and discriminated from LOPC data.
• MEASUREMENT AND MODELING OF THREE DIMENSIONAL TARGET STRENGTH OF FISH FOR HORIZONTAL SCANNING SONAR

  Muhammad Kurnia, Kohji Iida, Tohru Mukai

  JOURNAL OF MARINE SCIENCE AND TECHNOLOGY-TAIWAN 19 (3) 287 - 293 1023-2796 2011/06 [Refereed][Not invited]
   

  This paper discusses the three-dimensional target strength (3DTS) of fish for a horizontal scanning sonar. Experiments were conducted in a tank using a defrosted Japanese mackerel. Measurements were made by changing the horizontal incident angle of a 50 kHz acoustic beam and the pitch angle of a tethered fish. Following the experiment, morphological characteristics, including the swimbladder size and shape, were measured using soft X-ray and digitized. The theoretical 3DTS was estimated using the prolate spheroid model and compared with the measured 3DTS. Results showed that the TS strongly depended on the fish orientation. The maximum and minimum TS were recorded at the broadside and the head/tail aspect of the fish, respectively. The horizontally averaged TS, which is necessary to estimate fish abundance by horizontal scanning sonar, gradually increased as the pitch angle increased, showing a minimum at 0 degrees and maximum at 90 degrees. The measured horizontally averaged TS was 3-5 dB lower than the theoretically estimated TS. Possible theoretical, biological, and technical reasons are discussed.
• Effect of artificial light on sampling with plankton net for euphausiid

  FUJIMORI YASUZUMI, MUKAI TOHRU, YAMAMOTO JUN

  NIPPON SUISAN GAKKAISHI 日本水産學會 76 (6) 1080 - 1082 0021-5392 2010/11/15 [Refereed][Not invited]
   

  オキアミ採集におけるライトの効果を確認するとともに，その有無が採集個体のサイズ組成に与える影響を調べた。採集には口径 80 cm（NGG32）のリングネットを使用した。ペンネント上部にネット上方に光を照射するようにライトを取りつけ，ライト無し，点灯，閃光（点滅）の 3 条件について夜間に鉛直曳網を行った。ライトをつけた場合では点灯，閃光に関わらず，ライト無しの場合よりも密度は 4～6 倍に増加した。また，採集個体の体長組成はライトの有無で大きく異なり，点灯，閃光に関わらず大型個体の採集量は著しく増加した。
  
• Characteristics of Acoustic Scattering according to Pulsation of the Large Jellyfish Nemopilema nomurai

  韓国水産学会誌 43 (5) 551 - 556 2010 [Refereed][Not invited]
  
• The acoustic characteristics of three jellyfish species: Nemopilema nomurai, Cyanea nozakii, and Aurelia aurita

  Miyuki Hirose, Tohru Mukai, Doojin Hwang, Kohji Iida

  ICES JOURNAL OF MARINE SCIENCE 66 (6) 1233 - 1237 1054-3139 2009/07 [Refereed][Not invited]
   

  Reports about jellyfish damaging nets and reducing fish catches are increasing, and data on the abundance and distribution of various jellyfish species are needed to forecast where and when their blooms will happen. Acoustic techniques can be used to obtain this information if the acoustic characteristics of the targets are known. This is a study of acoustic scattering from three jellyfish species: Nemopilema nomurai (order Rhizostomeae), Cyanea nozakii (Semaeostomeae), and Aurelia aurita (Semaeostomeae). Target strength (TS) at 38, 120, and 200 kHz, specific density, and sound speed were measured with live specimens. Specific densities were measured using the displacement-volume-weight and the dual-density methods. The sound speeds were estimated using the time-of-flight method. The reduced TS (RTS), i.e. the TS normalized by bell area, was smaller for N. nomurai (bell diameter range 19-38 cm) than for C. nozakii (bell diameter range 30-40 cm), and the differences in RTS between the species were 17.8, 12.6, and 5.8 dB at 38, 120, and 200 kHz, respectively. The respective sound-speed contrast h and density contrast g were 1.0008 +/- 0.009 (mean +/- s.d.) and 1.004 +/- 0.015 for N. nomurai; 1.038 and 1.073 for one C. nozakii; and 1.0001 +/- 0.025 and 0.989 +/- 0.019 for A. aurita.
• 小型海洋生物のターゲットストレングス(TS)パターン測定における対話的解析

  石井憲, 安部幸樹, 澤田浩一, 甘糟和男, 向井徹

  超音波Techno 21 (2) 66 - 69 0916-2410 2009/04 [Refereed][Not invited]
  
• The variation of density and sound speed contrasts and theoretical target strength estimation of Euphausia pacifica

  MATSUKURA RYUICHI, MUKAI TOHRU, ANDO YASUHIRO, IIDA KOHJI, RYUICHI MATSUKURA, TOHRU MUKAI, YASUHIRO ANDO, KOHJI IIDA, Graduate School of Environmental Science Hokkaido University, Faculty of Fisheries Sciences Hokkaido University, Faculty of Fisheries Sciences Hokkaido University, Faculty of Fisheries Sciences Hokkaido University

  NIPPON SUISAN GAKKAISHI 日本水産學會 75 (1) 38 - 44 0021-5392 2009/01/15 [Refereed][Not invited]
   

    The density and sound speed contrasts between Euphausia pacifica and sea water change with the season. In this study, we examined the effect on target strength (TS) and lipid content which is a cause of these changes. Density contrasts increased from spring to summer, but sound speed contrasts decreased. There was a negative correlation between density contrasts and wax esters, which are one of the lipid contents, and a positive correlation between sound speed contrasts and total lipid. The range of variation estimated by the DWBA model using both ratios was narrow. The mean TS of E. pacifica (TL 15 mm) ranged from -105.9 to -105.2 dB at 38 kHz, from -91.3 to -90.5 dB at 120 kHz and from -86.3 to -85.4 dB at 200 kHz.
  
• Distribution of murres (Uria spp.) and their prey south of St. George Island in the southeastern Bering Sea during the summers of 2003-2005

  Nobuo Kokubun, Kohji Iida, Tohru Mukai

  DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY 55 (16-17) 1827 - 1836 0967-0645 2008/08 [Refereed][Not invited]
   

  The distributions of murres (Uria spp.) and their prey were examined on board T/S Oshoro maru in the southern part of St. George Island, southeastern Bering Sea during the summers of 2003-2005. Murre distribution was determined by sight-counting survey, and the biomass of fishes and plankton was estimated simultaneously using acoustic measuring. Fish were abundant in intermediate (30-90m) layers around the inner front or the northern edge of Pribilof Canyon, while plankton were abundant in deep (> 90 m) layers around the northern edge of Pribilof Canyon or the shelf-break front. In each year, murres foraged around the inner front or the northern edge of Pribilof Canyon, which had high productivity and abundant fish, as has been revealed previously. Non-linear regression analysis on the vertical distribution of prey and distribution of murres suggested that murres especially targeted on fishes concentrated in intermediate layers below the thermocline. Furthermore, comparison of abundance and distribution of prey revealed that fish abundance was lower and distributed in deeper layers in 2005 than in 2003 and 2004. Low abundance and deep distribution of fish prey may be related to poor breeding success of murres on St. George Island in 2005. (C) 2008 Elsevier Ltd. All rights reserved.
• Verification of mean volume backscattering strength obtained from acoustic Doppler current profiler by using sound scattering layer

  LEE KYOUNGHOON, MUKAI TOHRU, LEE DAEJAE, IIDA KOHJI

  Fisheries science : FS 74 (2) 221 - 229 0919-9268 2008/04/01 [Refereed][Not invited]
   

  Acoustic Doppler current profilers (ADCPs) have recently been used to estimate the dynamic characteristics and biomass of sound scattering layers (SSLs) or swimming speed of fish schools and to analyze SSL spatial distribution or various behavior patterns. This paper shows that it is necessary to verify mean volume backscattering strength (MVBS, dB) values acquired from each beam for quantitative analysis of the spatial distribution or the biomass estimates of such specific targets as SSL or a fish school when using an ADCP. In this study, the SSL was selected to be a homogeneous density layer over a large area and two methods were used to verify the MVBS values from each beam of the ADCP. First, a mutual comparison among four beams was conducted after calculating MVBS from the measured echo intensity. Second, the MVBS values were verified using comparison between the calculated MVBS from the 153.6 kHz ADCP and MVBS from three frequencies of a well-calibrated scientific echosounder. Moreover, the dominant scatterers (euphausiids) were collected by a framed midwater trawl. From these samples, biological data were used to identify the different frequency characteristics between two systems, using a distorted-wave Born approximation (DWBA) theoretical backscattering model in order to assess the averaged target strength and target strength TS differences for the three frequencies.
• A Trousers-Type Framed Midwater Trawl for Simultaneous Sampling of Plankton and Micronekton:Size Selectivity of Minnow Netting for Euphausiids

  FUJIMORI Yasuzumi, YAMASHITA Yukiko, ABE Masayuki, ITAYA Kazuhiko, MUKAI Tohru

  Journal of Fisheries Engineering 日本水産工学会 44 (3) 197 - 204 0916-7617 2008 [Refereed][Not invited]
   

  A trousers-type framed midwater trawl (T-FMT) was developed for the simultaneous sampling of plankton and micronekton, which allows the use of two kinds of mesh sizes at the same time. This paper describes the performance of T-FMT in the survey of plankton and micronekton. In addition, the estimation of size selectivity for these small creatures was conducted by using the SELECT analysis expanded for a sub-sample from the trousers trawl experiment. The experiments for plankton and juvenile walleye pollock were conducted offshore of Usujiri, Hokkaido. Three kinds of codends were prepared: two moji-nets with mesh sizes of 1.7mm (M17) and 3.1mm(M31), respectively, and a plankton mesh with a mesh size of 526μm (PL). A pair of codends, M17 vs. PL and M17 vs. M31, was tested for sampling plankton and juvenile walleye pollock, respectively. Euphausiids dominated the catches of the M17 codend, whereas copepods were dominant in the PL codend. The Iength distribution of euphausiids in the PL codend showed a bimodal shape, whereas of those in the M15 codend showed a unimodal shape. The average L_<50> and S. R. values for the estimated selectivity curve of the M17 codend for euphausiids were 7.8 and 1.0mm, respectively. For the juvenile walleye pollock caught in April (early season after spawning), the length distribution in the M17 and M31 codends showed a deviant shape, i.e. there were no fish smaller than 12mm in length. For the fish caught in June, the length distributions for the M17 and M31 codends showed a unimodal shape, and there was no difference in length distribution between the M17 and M31 codends. Based on these results, it was concluded that the PL and M17 codend pair was suitable for the simultaneous sampling not only of plankton and micronekton but also of juvenile walleye pollock in this area from April to June. In addition, the availability of T-FMT in the study of size selectivity for small creatures was confirmed.
• Transportation of organic matter to the sea floor by carrion falls of the giant jellyfish Nemopilema nomurai in the Sea of Japan

  Jun Yamamoto, Miyuki Hirose, Tetsuya Ohtani, Katashi Sugimoto, Kazue Hirase, Nobuo Shimamoto, Tsuyoshi Shimura, Natsumi Honda, Yasuzumi Fujimori, Tohru Mukai

  MARINE BIOLOGY 153 (3) 311 - 317 0025-3162 2008/01 [Refereed][Not invited]
   

  The fate of the giant jellyfish Nemopilema nomurai after death was examined in the southwest Sea of Japan. The density of dead jellyfish was greater than that of live animals. The dead animals are heavier than the Japan Sea Proper Water which occurs deeper than 200 m, suggesting that dead jellyfish sink to the sea floor. The sea floor survey, conducted with a towed video tape recorder (VTR) monitoring system between mid September and mid October, observed a total of 138 jellyfish during 28 of 29 operations. The density of carrion ranged between 0.2 and 5.1 individuals/1,000 m(2) (mean +/- SE = 1.1 +/- 0.2). Ophiuroids occurred abundantly at 23 jellyfish carcasses and a sea anemone was observed attached to five carcasses. The VTR surveys confirmed that carrion sinks to the sea floor not only during the winter, the normal end of life for medusae, but also during the fall. A trap survey baited with medusae was also employed, and four different species were sampled with the traps: the snow crab (Chionoecetes opilio), a shrimp (Pandalopsis japonica), the ivory shell (Buccinum striatissimum) and an ophiuroid (Ophiura sarsii). Much of the trap bait remained (49-68% weight-mean = 60.3%) during the 23 h soak-time, and the reduction in weight was greater than that observed by bacterial decomposition, suggesting benthic animals consume dead organisms. The present study indicates that dead N. nomurai sink to the sea floor continuously and were subsequently consumed by benthic scavengers.
• Measurements of specific density of and sound speed in nomura's jellyfish Nemopilema nomurai to estimate their target strength using a theoretical scattering model

  HIROSE Miyuki, MUKAI Tohru, SHIMURA Tsuyoshi, YAMAMOTO Jun, IIDA Kohji

  The Journal of the Marine Acoustics Society of Japan 海洋音響学会 34 (2) 109 - 118 0916-5835 2007/04 [Refereed][Not invited]
   

  The jellyfish Nemopilema nomurai, which reaches up to 2 m in diameter and 200 kg in weight, has appeared in large numbers in the Sea of Japan during the last several years and has had a negative effect on coastal fisheries in this region. Data on the abundance and distribution of these jellyfish are needed to forecast when and where they will occur in coastal areas. Acoustic techniques are commonly used to study the distribution and abundance of fish and zooplankton because these techniques can survey large areas relatively quickly. Before such surveys can be conducted, the acoustic characteristics of the target species must be known. In this study, the density and speed-of-sound in live jellyfish were measured in order to clarify their acoustic characteristics using a theoretical scattering model. The density of the jellyfish was measured using the dual-density method, while the speed of sound was measured using the time-of-flight method. Their acoustic characteristics were estimated with the distorted-wave Born approximation (DWBA) model using these material properties and the shape of free-swimming jellyfish. The results demonstrate the feasibility of investigating the abundance and distribution of jellyfish using acoustic methods.
• Estimation of zoo plankton biomass using the LOPC

  山下 由起子, 藤森 康澄, 向井 徹

  Mathematical and physical fisheries science 数理水産科学研究会 5 97 - 104 1348-6802 2007 [Refereed][Not invited]
  
• Density and sound speed contrasts of the Japanese common squid Todarodes pacificus and their influence on acoustic target strength

  KANG DONHYUG, IIDA KOHJI, MUKAI TOHRU, KIM JONGMAN

  Fish. Sci. 72 (4) 728 - 736 0919-9268 2006/08/01 [Refereed][Not invited]
   

  In this study, density and sound speed contrasts were measured for the Japanese common squid Todarodes pacificus. Target strength (TS) data derived from an acoustic scattering model based on measurements of these two parameters were compared with TS values based on acoustic measurement data to determine whether the measured parameters are reasonable values for theoretical scattering model. Density contrast (g) was measured from the displacement volume and wet weight, while sound speed contrast (h) was measured from the acoustic measurements of travel time (time-of-flight method). The Kirchhoff ray mode model, which represents the squid body as a set of fluid-filled cylinders, was used to calculate theoretical TS. Mean g- and h-values of the squid were 1.029 and 1.041, respectively. Comparison with previous data showed that g was similar, whereas h was relatively high. The difference in the TS between the theoretical model using measured parameters and the acoustic measurement was within 3 dB. Thus, the measured g- and h-values are acceptable for theoretical models of squid.
• Observation of marine animals using underwater acoustic camera

  K Iida, R Takahashi, Y Tang, T Mukai, M Sato

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 45 (5B) 4875 - 4881 0021-4922 2006/05 [Refereed][Not invited]
   

  An underwater acoustic camera enclosed in a pressure-resistant case was constructed to observe underwater marine animals. This enabled the measurement of the size, shape, and behavior of living marine animals in the detection range up to 240 cm. The transducer array of the acoustic camera was driven by 3.5 MHz ultrasonic signals, and B-mode acoustic images were obtained. Observations were conducted for captive animals in a water tank and for natural animals in a field. The captive animals, including fish, squid and jellyfish, were observed, and a three-dimensional internal structure of animals was reconstructed using multiple acoustical images. The most important contributors of acoustic scattering were the swimbladder and vertebra of bladdered fish, and the liver and reproductive organs of invertebrate animals. In a field experiment, the shape, size, and swimming behavior of wild animals were observed. The possibilities and limitations of the underwater acoustic camera for fishery applications were discussed.
• Estimation of fish school volume using onmidirectional multi-beam sonar: Scanning modes and algorithms

  Y Tang, K Iida, T Mukai, Y Nishimori

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 45 (5B) 4868 - 4874 0021-4922 2006/05 [Refereed][Not invited]
   

  Previous studies have resulted in a quantitative omnidirectional sonar (FSV30 research version, Furuno) using 64 multi-beams and a 24 kHz center operating frequency. The practical applications of this sonar are currently being studied with regard to fisheries resource assessment. This paper presents one part of this research, i.e., methods for estimating fish school volume using different sonar scanning modes. To determine its suitability for various purposes, we conducted a simulation to measure scatter aggregation; the simulation was validates by measuring the volume of a balloon filled with seawater. A practical survey was also simulated for spherical scatter aggregation with a 20 m, diameter, and its volume was examined using different scanning modes. Our results indicate that a semicircular cruise mode is more suitable than a circular mode for measuring fish school volume, and that using an anchored instrument scanning mode provides greater accuracy than a cruising scanning mode.
• Characteristics of vocalizations in Steller sea lions

  Tae-Geon Park, Kohji Iida, Tohru Mukai

  SEA LIONS OF THE WORLD 549 - 560 2006 [Refereed][Not invited]
   

  We investigated the acoustics of Steller sea lion (Eumetopias jubatus) calls in wild individuals hauled out on shore reefs off the west coast of Hokkaido, northern Japan, and in captive sea lions at an aquarium using video camera observations. Steller sea lion calls were classified as "communication," "threat," "wheedling," and "acknowledge" according to associated behaviors. Classified calls were analyzed by means of sonograms for formant frequency (F-1), sound duration (T), and pitch pattern. All sounds emitted by males were lower in formant frequency than those of females, while sounds made by wild animals were lower than those of captive animals. Sounds by males were also longer in duration than those by females, while those made by wild animals were shorter than those by captive ones. Pitch of "communication" calls was a long flat pattern type, "threat" was a short descending type, and "wheedling" was a short ascending type for wild animals and a short wave-like type for the captives. The characteristics of pitch patterns of wild and captive animals suggest that the calls of Steller sea lions are for communication.
• Avoidance of artificial stimuli by the Steller sea lion

  Kohji Iida, Tae-Geon Park, Tohru Mukai, Shoji Kotani

  SEA LIONS OF THE WORLD 535 - 548 2006 [Refereed][Not invited]
   

  Every winter, hundreds of Steller sea lions (Eumetopias jubatus) visit the coast of Hokkaido, northern Japan. Their foraging behavior destroys fishing gear, which is a serious problem. In order to find a solution that allows the coexistence of both Steller sea lions and fishing activities, attempts have been made to control their behavior using acoustical and optical stimuli. This study examined methods of repelling Steller sea lions from fishery gear using aerial and underwater sounds and flashing lights. In this study, we (1) observed and analyzed the relationship between the calls and the behavior of Steller sea lions; (2) searched for effective stimuli for repelling Steller sea lions; (3) developed a displacing system that generates artificial stimuli to repel Steller sea lions using sounds and lights; and (4) tested the displacing system. Experiments were conducted at a Steller sea lion haul-out located on the west coast of Hokkaido, on the Sea of Japan. Steller sea lions were exposed to acoustical and optical stimuli consisting of repeated intermittent sounds with or without flashing lights. This system was controlled from the edge of a cliff, and the reactions of Steller sea lions were monitored using a video camera and microphone. Most of the Steller sea lions responded to the stimuli by vocalizing toward the source, while moving away and jumping in the water. The most effective stimuli for repelling Steller sea lions were aerial sounds, underwater sounds, and flashing lights in that order.
• Target strength measurements on tethered live jellyfish Nemopilema nomurai

  HIROSE MIYUKI, MUKAI TOHRU, HWANG DOOJIN, IIDA KOHJI, MIYUKI HIROSE, TOHRU MUKAI, DOOJIN HWANG, KOHJI IIDA, Graduate School of Fisheries Sciences Hokkaido University, Graduate School of Fisheries Sciences Hokkaido University, College of Fisheries and Ocean Science Yosu National University, Graduate School of Fisheries Sciences Hokkaido University

  NIPPON SUISAN GAKKAISHI 日本水産學會 71 (4) 571 - 577 0021-5392 2005/07/15 [Refereed][Not invited]
   

    The purpose of this study was to estimate the acoustic target strength (TS) of live Nomura's jellyfish Nemopilema nomurai found in the Yellow Sea and the Sea of Japan. The experiments were conducted at Yosu National University, Korea. Seven jellyfish were collected from coastal waters in southern Korea by SCUBA diving and from set-nets. Individual live jellyfish were suspended at the center of a seawater tank (5 m×5 m×5 m) tethered by thin fishing line, and their behavior was monitored by underwater cameras. The TS of each jellyfish was measured at 38 kHz (split-beam system) and 200 kHz (dual-beam system).
     The mean TS values ranged from -79.0 to -47.5 dB at 38 kHz and from -72.2 to -46.0 dB at 200 kHz, and tended to be higher at 200 kHz than at 38 kHz by 1.5 to 10.6 dB. The TS values of similar sized jellyfish were approximately 20 dB lower for those collected by SCUBA diving than those collected in the set-nets. The TS values also varied depending on the form change of the jellyfish.
  
• The influence of tilt angle on the acoustic target strength of the Japanese common squid (Todarodes pacificus)

  DY Kang, T Mukai, K Iida, DJ Hwang, JG Myoung

  ICES JOURNAL OF MARINE SCIENCE 62 (4) 779 - 789 1054-3139 2005/06 [Refereed][Not invited]
   

  To measure the influence of changes in tilt angle on the acoustic target strength (TS) of the Japanese common squid (Todarodes pacificus), we conducted a series of experiments to estimate TS in relation to tilt angle and swimming angle. Swimming angle was measured in a seawater tank using two infrared, underwater cameras under dark conditions. Ex situ measurements of TS in relation to tilt angle on live specimens using a fishhook and cage method were then conducted at 38 and 120 kHz; mantle length (ML) ranged from 21 to 27 cm (mean 24.75 cm). For the more precise TS measurement with tilt angle, another set of ex situ TS measurements relative to tilt angle was made at 38 and 120 kHz on tethered, anesthetized specimens in seawater. The mean swimming angle was - 17.7 degrees (+/- 12.7 degrees s.d.). The mean TS varied from -48.6 to -44.6 dB and was relatively higher at 120 kHz than at 38 kHz, in the order of 0.7 and 2.5 dB. The empirical relationship between TS (dB) and ML (cm) is given by TS = 20 log(10)(ML) - 75.4 (r = 0.81) at 38 kHz or TS = 20 log(10)(ML) - 73.5 (r = 0.64) at 120 kHz. Based on the tethered method for the anesthetized squid, the mean standardized TS values (b(20)) were found to be highly correlated with the tilt angle, and the resultant fitted equations for b20 were expressed as: b20 = -73.3 + 0.48 X theta + 0.0122 X theta(2) + 0.00016 X theta(3) for 38 kHz and b(20) = -72.6 + 0.53 X theta + 0.0134 X theta(2) + 0.00014 X theta(3) for 120 kHz, where theta is the negative tilt angle in degrees. The mean TS based on the measurements using live squid was higher than that of tethered measurements, i.e., 2.6 dB at 38 kHz and 4.0 dB at 120 kHz. The higher mean TS in the ex situ measurements for the live squid can be explained by the influence of the low tilt angle on the overall TS data. The results can be used to understand the influence of tilt angle on the TS of Todarodes pacificus and thus improve the accuracy of biomass estimates. (c) 2005 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
• Influence of Body Bend by Swimming Activity on Fish Target Strength

  SADAYASU Kazuhiro, ABE Koki, SAWADA Kouichi, TAKAO Yoshimi, MUKAI Tohru, IIDA Kohji

  The Journal of the Marine Acoustics Society of Japan 特定非営利活動法人 海洋音響学会 32 (1) 30 - 39 0916-5835 2005 [Refereed][Not invited]
   

  Understanding the variability of fish acoustic target strength (TS) potentially improves the accuracy of fisheries acoustic survey. This study examines the effect of fish body bending by swimming activity on fish target strength. Bending shape of fish body and swimbladder were simulated from soft X-ray images of anesthetized walleye pollock. Target strength of bent fish was estimated using a Kirchhoff Ray-Mode model from simulated morphology as a function of fish pitch angle. TS patterns of whole fish and swimbladder did not change near the pitch angle at which maximum TS was obtained. But at the other pitch angle, TS patterns of bent fish differed from that of no bent fish. TS patterns of fish body changed at all the pitch angle. Decrease of maximum TS caused by fish bending was within 0.7 dB. Present study indicates that it is not necessary to take care of fish bending on TS estimation, when fish swimming behaviour is normal except for feeding time that fishes are more active.
• Application of acoustic Doppler current profiler combined with a scientific echo sounder for krill Euphausia pacifica density estimation

  LEE KYOUNGHOON, MUKAI TOHRU, KANG DONHYUG, IIDA KOHJI

  Fisheries science : FS 70 (6) 1051 - 1060 0919-9268 2004/12/01 [Refereed][Not invited]
   

  An application of the acoustic Doppler current profiler (ADCP, 153.6 kHz) in combination with a scientific echo sounder (EK60, 38 and 200 kHz) was investigated to estimate the density of krill Euphausia pacifica. The acoustic backscattering strength from sound scattering layers was compared with biomass estimates from midwater trawls. Euphausia pacifica was targeted among mixed species populations in the sound scattering layer in the offshore Funka Bay area of Hokkaido, Japan. The frequency characteristics of acoustic backscattering by krill were calculated using a distorted wave Born approximation scattering model at three frequencies. Krill aggregations identified from the EK60 data were extracted as the mean volume backscattering strength difference between two frequencies. They were then used to identify similar aggregations in the ADCP data by matching observation times and depths for the two methods, which were applied simultaneously. Results from the comparison of the mean volume backscattering strength and the density calculated from the ADCP and EK60 showed that ADCP can be used to measure density and spatial-temporal distribution of krill aggregations. Current speed and direction at the study site were found to be 16.1 cm/s and 187.00, respectively, and krill speed and direction (including the current component) were found to be 19.8 cm/s and 172.20, respectively Based on the ADCP data, the net speed and direction of the krill aggregations were found to be 5.9 cm/s and 128.00, respectively.
• Target strength estimation of black porgy Acanthopagrus schlegeli using acoustic measurements and a scattering model

  KANG DONHYUG, SADAYASU KAZUHIRO, MUKAI TOHRU, IIDA KOHJI, HWANG DOOJIN, SAWADA KOUICHI, MIYASHITA KAZUSHI

  Fish. Sci. 70 (5) 819 - 828 0919-9268 2004/10/01 [Not refereed][Not invited]
   

  Black porgy are hatched and released in marine ranching areas in Japan, Korea and Taiwan to maintain fisheries resources in coastal areas. If acoustic methods are used for field surveys, target strength (TS) information on the species is needed to convert acoustic data to biomass density. Target strength of black porgy (Acanthopagrus schlegeli) 15.5 - 32.9 cm fork length (nine individuals) was measured at 38 and 120 kHz (split beam) by ex situ measurements (cage and fishhook methods) of living fish, a tethered method with shock-frozen fish, and an acoustic scattering model, the Kirchhoff ray mode (KRM) model based on fish morphology. The ex situ TS-to-fork length (FL, cm) relationships were TS38kHz = 20log(10)FL - 64.6 (r = 0.77) and TS120kHz, = 20log10FL - 65.2 (r = 0.70). The values for the KRM model were TS38kHz = 20log(10)FL - 64.8 (r = 0.88) and TS120kHz = 20log(10)FL - 65.4 (r = 0.80). The agreement between the ex situ measurements and the KRM model for the mean TS was very good. In contrast, the results for the tethered method (TS38kHz, = 20log10FL - 69.3 [r = 0.42]) differed markedly from the other two methods, perhaps because of the effects of the shock-freezing procedure in air. The results of the ex situ measurements and scattering model provide basic information for studying TS and conducting acoustic surveys of black porgy, even though the tethered method must be modified.
• Trial Observation of the Sound Scattering Layer Using an ROV

  YAMAMOTO Jun, MUKAI Tohru, IWAMORI Toshihiro, KIMURA Osamu, SAKURAI Yasunori

  Journal of the Japan Society for Marine Surveys and Technology 海洋調査技術学会 16 (2) 25 - 30 0915-2997 2004/09/30 [Refereed][Not invited]
   

  A remotely operated vehicle (ROV) was used to observe a sound scattering layer (SSL) identified using a quantitative echo sounder near the mouth of Funka Bay, Hokkaido. The SSL was seen in a high frequency (100kHz) echogram to occur within 5 m of the sea floor. Video images taken by the ROV showed a dense school of krill swimming rapidly and continuously within the SSL. Furthermore, several walleye pollock were observed to approach the ROV at depths where relatively strong echoes appeared in a low frequency (25kHz) echogram. The density and size of the krill and walleye pollock were not determined, however, it is clear that ROVs are useful for observing the SSL and can provide valuable information about the biomass of marine resources more accurately.
• Lipid Profile of Krill Euphausia pacifica Collected in the Pacific Ocean near Funka Bay, Hokkaido, Japan

  KUSUMOTO Nami, ANDO Yasuhiro, MATSUKURA Ryuichi, MUKAI Tohru

  Journal of Oleo Science 公益社団法人 日本油化学会 53 (1) 45 - 51 1347-3352 2004/01/01 [Refereed][Not invited]
   

  This paper reports the total lipid content, lipid class composition, and fatty acid composition of the krill Euphausia pacifica collected in the northwestern Pacific Ocean near Funka Bay, Hokkaido, Japan. The krill were caught in spring, summer, and winter in three consecutive years, 2000-2002. Lipid content of the E. pacifica samples was ranged from 5.1 to 11.6% on the basis of dry weight. Major lipid classes determined for the samples of 2002 were triacylglycerols (TAG) (3.4-27.3%), free fatty acids (FFA) (6.9-22.2%), sterols (5.4-12.9%), phosphatidylethanolamines (PE) (3.4-17.5%), and phosphatidylcholines (PC) (36.2-53.8%). All of the samples subjected to fatty acid analysis were high in 16:0 (19.0-24.5% of total fatty acids), 18:1n-9 (7.5-10.0%), 18:1n-7 (6.3-8.1%), 20:5n-3 (IPA) (15.3-24.7%), and 22:6n-3 (DHA) (8.4-20.7%). The lipids of E. pacifica were found to be generally rich in PC and in IPA and DHA. Lipid content and proportion of TAG were higher in the spring samples than in the summer samples. The summer samples were higher in the concentration of DHA in total fatty acids.
• Lipid Content and Fatty Acid Composition of Euphausia pacifica(Total Body Lengths Less than 13mm) Collected in the Water near Funka Bay

  KUSUMOTO N, Ando Yasuhiro, Matsukura Ryuichi, Mukai Tohru

  Bulletin of fisheries sciences, Hokkaido University 北海道大学大学院水産科学研究科 54 (3) 73 - 77 1346-1842 2003/12 [Not refereed][Not invited]
  
• Occurrence of acoustic attenuation by sailing corresponding with ship speed and sea condition in hydroacoustic surveys

  HONDA SATOSHI, SUZUKI CHIHIRO, MUKAI TOHRU, IIDA KOHJI

  NIPPON SUISAN GAKKAISHI 公益社団法人 日本水産学会 69 (4) 558 - 567 0021-5392 2003/07/15 [Refereed][Not invited]
   

  The attenuation of acoustic energy due to the effects of sailing were measured on the RV Kaiyo-maru No.3 by integrating the area backscattering strength (S_a) of the sea bottom. The attenuation of the bottom S_a appeared with the increase of the ship speed. In particular, the attenuation was apparent under the head sea condition of sailing ; maximum attenuation of 1.3 dB was attained at 38 kHz, and 0.7 dB at 12 kHz. On the other hand no clear attenuation occurred under the conditions of a following sea. Under the head sea condition of sailing, the attenuation by sailing occurred at a slower sailing speed than the appearance of a missing echo or apparent attenuation shown on the echogram. That is, the attenuation by sailing exerted an influence upon the acoustic data without the operator being aware of it. When planning an acoustic survey by the RV Kaiyo-maru No.3, or even in a survey field, setting the sailing direction in a following sea will prevent underestimation of the acoustic biomass index caused by the acoustic attenuation due to the effects of sailing.
• TAC制度下における直接法による資源量推定技術高度化試験

  本間隆之, 高柳志朗, 坂口健司, 三宅博哉, 和田昭彦, 武藤卓志, 飯田浩二, 向井徹, 中野健一

  北海道立中央水産試験場事業報告書 2001 149 - 150 2002/12 [Not refereed][Not invited]
  
• Use of Geographical Parameters of Fish School in the Estimation of Fish School Abundance Using Scanning Sonar

  Bull. Korean Soc. Fish. Tech. 38 197 - 291 2002 [Not refereed][Not invited]
  
• Observation of Juvenile Sourthern Bluefin Tuna (Thunnus maccoyi C.) School Response to the Approaching Vesel Using Scanning Sonar

  J.Fish.Sci.Tech. 5 206 - 211 2002 [Not refereed][Not invited]
  
• The Application of Image Processing Technology for the Analysis of Fish School Behavior: Evaluation of Fish School Behavior Responce to the Approaching Vessel Using Scanning Sonar

  J.Fish.Sci.Tech. 5 212 - 218 2002 [Not refereed][Not invited]
  
• Acoustic assessment and distribution of spawning walleye pollock Theragra chalcogramma in the Japan Sea off western Hokkaido using quantitative echo sounder.

  MIYAKE HIROYA, ISHIDA RYOTARO, MUTO TAKASHI, ABE KOKI, MUKAI TOORU, IIDA KOJI

  北海道立水産試験場研究報告 北海道立水産試験場 (59) 11 - 24 0914-6830 2001/03/30 [Not refereed][Not invited]
   

  1996～1998年の各年10月に北海道西岸日本海で，計量魚群探知機によりスケトウダラの空間分布を調べ，その現存量を推定した。スケトウダラは各年とも南側海域の大陸棚斜面域に多かった。分布深度は，沿岸域で，昼間380～440m，夜間340～460m，沖合域で，昼間420～580m，夜間340～500mであった。分布様式は昼夜で異なり，夜間には水平的，鉛直的に分散する傾向が見られ，特に上方への移動が顕著であった。これらから音響調査には夜間が適していると考えられた。昼夜込みのデータを用いて推定した現存量は，1996年が23万トン，1998年が45万トンであった。しかし，昼夜毎の推定値の比較から，これらは20%程度過小評価していると考えられた。また，空間サンプリング誤差は10%程度であったので，現存量の推定誤差の合計は約28%と推定された。
• Verification of diurnal change of target strength of walleye pollock. - An effect of resolution volume -

  Koki Abe, Satoshi Honda, Tatsuki Oshima, Kazushi Miyashita, Kohji Iida, Tohru Mukai

  Proceedings of the ACOUSTGEAR2000 1 48 - 54 2001 [Refereed][Not invited]
  
• Observation of juvenile southern bluefin tuna (Thunnus maccoyii C.) school in response to the approaching vessel using a scanning sonar

  Yoo-Won Lee, Kazushi Miyashita, Tsutomu Nishida, Sei-ichiro Harada, Tohru Mukai, Kohji Iida

  Proceedings of the ACOUSTGEAR2000 1 108 - 112 2001 [Refereed][Not invited]
  
• Evaluation Method of Fish School Response tu an Approaching Vessel Usinga Scanning Sonar

  LEE Yoo-won, MUKAI Tohru, IIDA Kohji

  NIPPON SUISAN GAKKAISHI 日本水産學會 66 (5) 825 - 832 0021-5392 2000/09/15 [Not refereed][Not invited]
   

  The response behavior of a fish school to an approaching vessel was observed using a scanning sonar. The evaluation method using six parameters which signify characteristics of school shape and behavior was proposed. In the two trial survey cruises, fifteen fish schools were analyzed, and among them five schools were identified for their changing shape, swimming direction, and swimming speed. Moreover, by continuously tracing fish schools on the sonar display, these fish schools were seen to exhibit an apparent change of school shape and behavior. Therefore, the evaluation method of fish school behavior using six characteristic parameters indicating fish school shape and behavior is useful.
• Measurements of Density and Sound Speed Contrasts for Estimating Krill Target Strength Using Theoretical Scattering Models

  MIKAMI Hisayuki, MUKAI Tohru, IIDA Kohji

  NIPPON SUISAN GAKKAISHI 日本水産學會 66 (4) 682 - 689 0021-5392 2000/07/15 [Not refereed][Not invited]
   

  In recent years, acoustic technology has been extensively used for estimating krill abundance. This acoustic assessment is required for precise estimate of target strength (TS) of a krill. However, prediction of the target strength from the theoretical scattering models is generally dependent on the swimming angle, the density and sound speed contrasts between krill and seawater. In these parameters, the density contrasts and sound speed contrasts are known to change during the year. In this study, the seasonal variations of the specific density and sound speed contrasts of Euphausia pacifica are presented. The specific densities of E. pacifica were measured in a series of saline or glycerol solutions of different densities. The measurements of the sound speed were performed using T-shaped velocimeter with two transducers mounted at the ends of the horizontal tube. The specific densities of E. pacifica changed about 1% with season. The sound speed contrasts also varied about 3% with season. These seasonal changes yielded difference about 5dB in target strength of E. pacifica calculated from a straight cylinder model.
• Target strength measurement of live fish using a net cage

  IIDA K.

  Proceedings of the 3rd JSPS International Seminar on Sustainable Fishing Technology in Asia towards the 21st Century 214 - 219 2000 [Not refereed][Not invited]
  
• Diurnal Changes of Area Backscattering Coefficient during the Acoustic Surveys of Walleye Pollock

  ABE Koki, IIDA Kohji, MUKAI Tohru

  NIPPON SUISAN GAKKAISHI 日本水産學會 65 (2) 252 - 259 0021-5392 1999/03/15 [Not refereed][Not invited]
   

  The influence of diurnal vertical migrations of walleye pollock on acoustic survey was investigated. The experiments were conducted at Musashi-Tai and off Shakotan Peninsula in northern Japan Sea using a split beam type scientific echo-sounder SIMRAD EK500. Area backscattering coefficient (S_A) and target strength (TS) of walleye pollock were measured in the daytime and in the nighttime. Results showed that the S_A in the nighttime was three times higher than S_A in the daytime in Musashi-Tai. Also the S_A in the nighttime was 1.4 times higher than that in the daytime off Shakotan Peninsula. However, there were no significant differences of in situ TS of walleye pollock between day and night in both areas. Since the remarkable vertical migration of walleye pollock in bottom layer was observed in echograms, it is concluded that the diurnal changes of S_A were caused by underestimation due to the hiding of the shoal of walleye pollock in acoustic deadzone near the bottom in the daytime.
• Frequency Characteristics of Acoustic Volume Backscattering Strength of Sound Scattering Layer and Estimation of Target Strengths of Constituent Organisms

  IIDA Kohji, MUKAI Tohru, MORI Hideki

  NIPPON SUISAN GAKKAISHI 日本水産學會 65 (1) 66 - 72 0021-5392 1999/01/15 [Not refereed][Not invited]
   

  Acoustic volume backscattering strength (SV) was measured at frequencies of 38, 50, 120 kHz from zooplankton and juvenile fish in the sound scattering layer (SSL) off northwestern Hokkaido. Organisms in the SSL were collected by beam trawl hauls at eight stations where the acoustic measurements were recorded. Euphausiids, copepods and juvenile walleye pollock were abundant organisms in the SSL. The composition of the species of sampled organisms was different at each station. When euphausiids were dominant in the SSL, the SV increased with acoustic frequencies. When juvenile walleye pollock were dominant, the SV showed a higher value than that in the above situation, and it was less changed by acoustic frequencies. These differences were explained by the frequency characteristics of acoustic backscattering of euphausiids and walleye pollock. The target strengths of euphausiids and juvenile walleye pollock were estimated by the multiple linear regression model. The results showed that there were some differences between estimated TS and theoretical TS, and the possibility of estimating TS using the multiple linear regression model.
• Acoustic Backscattering Characteristics of Swimbladderred Juvenile Fish Derived from Cage Experiments

  IIDA Kohji, MUKAI Tohru, HWANG Doo-Jin

  Fisheries Science Japanese Society of Fisheries Science 64 (6) 929 - 934 0919-9268 1998/12/01 [Not refereed][Not invited]
   

  Acoustic target strengths of captive juvenile fishes of three species were measured at four frequencies using fish cage method. Measurements were conducted on a barge constructed at a fishing port for the experiments, Measured fish were sea smelt Hypomesus pretiosus japonicus (Brevoort), goldeye rockfish Sebastes inermis (Cuvier), and purple puffer Takifugu porphyreus (Temminck et Schlegel). They were caught with a miniature purse seine and maintained in fish breeding tanks before the experiments. Their body lengths ranged from 30 to 65 mm. Each species was classified into three size classes. Specimens were maintained in a cubical cage of 0.5 m each side made of lace cloth during measurement. The echo signals from encaged fish at 25, 50, 100, and 200 kHz were recorded with a data recorder. Echo signals were later digitized and processed by squared integration to calculate the target strengths. The results show that, (1) The backscattering strength of encaged juveniles indicates a linear density dependence for most sample sets, (2) The normalized target strengths TScm of juveniles ranged from -66 to -55 dB, which is maximum 10 dB higher than that of adults, (3) Target strength changed by the frequency, that is, the TScm for L/lambda less than or equal to 2 was roughly 10 dB higher than the TScm for L/lambda greater than or equal to 2.
• Coastal Fisheries in the Waters off Joban and the Kashima-nada Seas-Stocks of Demersal Fishes and Their Fisheries. Acoustic assessment of spawning populations in walleye pollock.

  MIYAKE HIROYA, KANETA TOMONORI, MIZUNO MASAMI, YOSHIDA HIDEO, ISHIDA RYOTARO, NATSUME MASASHI, IIDA KOJI, MUKAI TOORU

  水産海洋研究 62 (1) 30 - 32 0916-1562 1998/02 [Not refereed][Not invited]
  
• Acoustic assessment of spawning populations in walleye pllock

  MIYAKE Hiroya, KANETA Tomonori, MIZUNO Masami, YOSHIDA Hideo, ISHIDA Ryotaro, NATSUME Masashi, IIDA Kohji, MUKAI Tohru

  Bulletin of the Japanese Society of Fisheries Oceanography 水産海洋学会 62 (1) 30 - 32 0388-9149 1998/02/01 [Not refereed][Not invited]
  
• Three dimensional analysis of distribution and shape of pelagic/mesopelagic fish school using scanning sonar

  IIDA Kohji, MUKAI Tohru, HORIUCHI Noritaka

  The Journal of the Marine Acoustics Society of Japan 特定非営利活動法人 海洋音響学会 25 (4) 240 - 249 0916-5835 1998 [Not refereed][Not invited]
   

  Sonar images obtained from a scanning acoustical beam are usually two-dimensional sectional images. However, since the sectional images can be easily obtained as an observation vessel moves forward, we can reconstruct three-dimensional images of underwater objects by analyzing stacked two-dimensional sectional images.
  The echo survey was conducted in Funka Bay aboard the R/V Ushio Maru, which is equipped with a 180-degrees sector scanning sonar (model KCH 1827, Kaijo Co. LTD). The sonar beam was directed downward perpendicularly to the ship's course. Vertical sectional sonar images were digitized every 1.5 seconds while the vessel was cruising at 10 knots. The stacked sectional images were analyzed to determine the spatial distribution and shape of fish schools using the three-dimensional image processing software SLICER.
  The distribution of fish schools was displayed by simultaneous expression of both horizontal and vertical projections. This expression method enabled us to observe fish avoidance from vessel, which can not be observed using ordinary vertical echo sounders.
  The reconstructed solid shape of fish schools by volume rendering could be observed by changing the visual point freely. This allowed to determine scale, features, and swimming direction of the fish schools. Three-dimensional display of sector scanning sonar images is a useful tool not only for a commercial fishing, but also for scientific surveys of fish resources and underwater drifters.
• Three Dimensional Visualization of Fish Schools using Sector Scanning Sonar

  International Archives of Photogrammetry and Remote Sensing 32 729 - 734 1998 [Not refereed][Not invited]
  
• Three dimensional analysis of distribution and shape of pelagic/mesopelagic fish school using scanning sonar

  IIDA Kohji, MUKAI Tohru, HORIUCHI Noritaka

  The Journal of the Marine Acoustics Society of Japan 特定非営利活動法人 海洋音響学会 25 (4) 240 - 249 0916-5835 1998 [Not refereed][Not invited]
   

  Sonar images obtained from a scanning acoustical beam are usually two-dimensional sectional images. However, since the sectional images can be easily obtained as an observation vessel moves forward, we can reconstruct three-dimensional images of underwater objects by analyzing stacked two-dimensional sectional images.<BR>The echo survey was conducted in Funka Bay aboard the R/V Ushio Maru, which is equipped with a 180-degrees sector scanning sonar (model KCH 1827, Kaijo Co. LTD). The sonar beam was directed downward perpendicularly to the ship's course. Vertical sectional sonar images were digitized every 1.5 seconds while the vessel was cruising at 10 knots. The stacked sectional images were analyzed to determine the spatial distribution and shape of fish schools using the three-dimensional image processing software SLICER.<BR>The distribution of fish schools was displayed by simultaneous expression of both horizontal and vertical projections. This expression method enabled us to observe fish avoidance from vessel, which can not be observed using ordinary vertical echo sounders.<BR>The reconstructed solid shape of fish schools by volume rendering could be observed by changing the visual point freely. This allowed to determine scale, features, and swimming direction of the fish schools. Three-dimensional display of sector scanning sonar images is a useful tool not only for a commercial fishing, but also for scientific surveys of fish resources and underwater drifters.
• Improvement in bottom detection for research of demersal fish using hydroacoustics.

  Hwang Doojin, Iida Kohji, Mukai Tohru

  The Journal of the Marine Acoustics Society of Japan 特定非営利活動法人 海洋音響学会 24 (3) 165 - 175 0916-5835 1997 [Not refereed][Not invited]
   

  The bottom detection is very important for defining an integration layer with the bottom as a reference basis during acoustic survey of demersal fish.
  Therefore, we have considered theoretically elements which form bottom echoes, and have devised a stable bottom detection method namely maximum differential voltage method, which was not influenced by variable levels and waveform transformation. The method has been shown to be effective using in-situ bottom echo waveforms and computer simulation data.
  A comparison between near-botton SV profiles acquired in Funka Bay Hokkaido of Japan and East China Sea, with the threshold method and maximum differential voltage method, shows that the SV obtained with the maximum differential voltage method is 4-6 dB higher within 2m from the bottom.
• On the depth dependence of fish target strength

  MUKAI T

  ICES C. M. 7 1 - 15 1997 [Not refereed][Not invited]
  
• Target Strength measurements of isada krill Euphausia pacifica using the cage method

  MIYASHITA Kazushi, AOKI Ichiro, IIDA Koji, MUKAI Tohru, HWANG Doojin

  Bull. Jpn. Soc. Fish. Oceanogr. 水産海洋学会 60 (2) 130 - 135 0388-9149 1996/05/25 [Not refereed][Not invited]
  
• Depth dependence of target strength of live kokanee salmon in accordance with Boyle's law

  T Mukai, K Iida

  ICES JOURNAL OF MARINE SCIENCE 53 (2) 245 - 248 1054-3139 1996/04 [Not refereed][Not invited]
   

  The target strength (TS) of fish varies with a number of factors, especially the presence or absence of a swimbladder. This study investigated the effect of the swimbladder on the TS of live kokanee (Oncorhynchus nerka) in relation to depth. Experiments were conducted at Lake Kuttara, Hokkaido, Japan, which is abundant with kokanee. Fish samples were caught with a fishing net. The live fish were suspended on the sound beam axis, and tilted from -50 degrees (head-down aspect) to +50 degrees (head-up aspect). The dorsal aspect TS functions were measured al 50 kHz. Measurements were performed when the fish were forced to change depth rapidly. The TS values were measured as a function of tilt angle and depth, and the maximum dorsal aspect TS (TSmax) values and the averaged dorsal aspect TS (TSavg) values were calculated and compared. TSavg values were calculated with respect to fish tilt-angle distribution, which was assumed to have a mean value of -5 degrees and a standard deviation of 15 degrees. Both TSmax and TSavg decreased with depth in accordance with Boyle's law, i.e. a reduction rate of 6.7 dB per 10 atm was observed. (C) 1996 International Council for the Exploration of the Sea
• Relationship between acoustic backscattering strength and density of zooplankton in the sound-scattering layer

  K Iida, T Mukai, DJ Hwang

  ICES JOURNAL OF MARINE SCIENCE 53 (2) 507 - 512 1054-3139 1996/04 [Not refereed][Not invited]
   

  Hydroacoustic sampling in the ocean is a useful technique for studying the biomass and structure of the distribution of marine organisms, including zooplankton. Acoustical and biological sampling of zooplankton in the sound-scattering layer (SSL) off the east coast of Oshima Peninsula, northern Japan has been conducted during the last 10 years to obtain the scale factor for converting the backscattering strength to biological density. The volume backscattering strength (SV) was measured at 25, 50, 100, and 200 kHz, while an IKMT (Isaacs-Kidd Midwater Trawl) and a Norpac (North Pacific standard net) were used to sample the biological organisms in the SSL. During drifting observation at dusk, the maximum speed of the upward migration of the SSL toward the surface was 3 m min(-1), and the SV changed over a range from -80 dB to -50 dB. Vertical lows of the Norpac indicated that euphausiids were the major zooplankton species of the migrating SSL. For quantitative analysis, the IKMT was towed horizontally about one hundred times, and the calculated density of zooplankton showed a maximum of 10g m(-3). We assumed that the acoustic reflectivity of the individual plankton was related to the size of the plankton squared, and that the acoustic backscattering strength of biomass was proportional to the distribution density, Results of regression analysis showed a linear relationship between the log of zooplankton density rho (mg m(-3)) and the acoustic volume backscattering strength SV (dB), with correlation coefficients greater than 0.5 at all frequencies. (C) 1996 international Council for the Exploration of the Sea.
• Three dimensional interpretation of sonar image for fisheries research

  K Iida, T Mukai, Y Aoki, T Hayakawa

  ACOUSTICAL IMAGING, VOL 22 22 583 - 588 1996 [Not refereed][Not invited]
  
• Auditory Characteristics of Walleye Pollock Theragra chalcogramma(Pallas)

  PARK Yong-seok, IIDA Kohji, MUKAI Tohru, SAKURAI Yasunori

  NIPPON SUISAN GAKKAISHI 日本水産學會 61 (2) 159 - 163 0021-5392 1995/03/15 [Not refereed][Not invited]
   

  The auditory threshold levels of walleye pollock Theragra chalcogramma (Pallas) were measured in order to determine the optimum conditions for marine ranching utilizing underwater sound. The auditory characteristics of walleye pollock were determined by heart beat conditioning using 8 frequencies of pure tone stimuli from 60 to 1, 000Hz coupled with an electric shock. Pure tone conditioning stimuli were presented to the fish for 5 seconds with a 0.1 second 12V DC electric shock applied 3 seconds after the start of the sound projection. The positive response to the pure tone stimulus of the conditioned fish consisted of an inhibition of one or more heartbeats.
  Results show that tested walleye pollock are sensitive to pure tones in the frequency range from 60 to 1kHz, with greatest sensitivity in the range from 120 to 200Hz. At the most sensitive frequencies, the mean thresholds were between 97.7 and 100.2dB (re 1μPa) under a background noise level between 55 and 75dB (re 1μPa/√Hz). Hearing ability declined gradually with increasing frequency above 400Hz. The upper limit of audible frequency is believed to be about 1kHz.
• Mechanisms of Sound Production in Walleye Pollock Theragra chalcogramma(Pallas)

  PARK Yong-seok, SAKURAI Yasunori, IIDA Kohji, MUKAI Tohru

  NIPPON SUISAN GAKKAISHI 日本水産学会 61 (2) 243 - 244 0021-5392 1995/03/15 [Not refereed][Not invited]
  
• Stable Bottom Detection and Optimum Bottom Offset for Echo Integration of Demersal Fish

  HWANG Doojin, IIDA Kohji, MUKAI Tohru

  NIPPON SUISAN GAKKAISHI 日本水産學會 61 (1) 43 - 50 0021-5392 1995/01/25 [Not refereed][Not invited]
   

  This paper discusses methods for the stable bottom detection and the optimum bottom offset which enable to separate the fish echoes from the bottom echoes with echo integration of demersal fish.
  In preprocessing of the echo signal, the bottom detection has to be done stably against the fluctuation of echo level and the bottom offset has to be set to a minimum height such that near bottom fish echoes are included.
  Two methods of bottom detection, namely echo level threshold method and maximum echo slope method were compared and analyzed. The echo level method works well if the ideal threshold level was given but it sometimes misses the bottom because of the fluctuation of the echo. Another method to detect the bottom which uses maximum echo slope indicates the simple and stable bottom detection.
  In addition, the bottom offset has to be set near to the bottom but not to include the bottom echo. Optimum bottom offset should be set a few samples before the detected bottom echo which relates the beginning of pulse shape and acoustic beam pattern to the bottom feature.
• Acoustic Observation of Spawning Walleye Pollock Theragra chalcogramma and Hydrographic Condition in Funka Bay

  IIDA Kohji, MUKAI Tohru, HWANG Doojin, HAYAKAWA Tomoko, MATSUYAMA Yukihiro

  NIPPON SUISAN GAKKAISHI 日本水産學會 61 (1) 27 - 34 0021-5392 1995/01/25 [Refereed][Not invited]
   

  The distribution and behavior of so-called spawing walleye pollock Theragra chalcogramma around Funka Bay were investigated during the acoustic survey by the R/V “Ushio Maru” in late 1993.
  Three types of echo, namely, near surface echo patches, near bottom echo patches and the sound scattering layer (SSL) in the middle layer, were recorded on the echogram of the dual frequency quantitative echo sounder.
  Hydrographic data by CTD observation showed that cold and less salty water mass below 5°C and 33.5 layers on the bottom of the shelf of Oshima Peninsula then formed a water front along the boundaries to surrounded the warmer and more salty waters.
  By comparing the hydrographic and acoustic dana, the sound scattering layer appeared along the water front and demersal echo patches were found in great numbers in the cold water mass, Activity of fishing boats and hydrographic conditions in this area suggested that the demersal echo patches were the schools of walleye pollock which were migrating for spawning and the sound scattering layer consisted of zooplankton aggregation in the water front.
  Distribution of the echograms indicated that the height of fish schools were 1 to 4 meters and the SV of the echo were about -65 to -60 dB. The density of the schools of walleye pollock along the transects were 5.8 in November to 8.1 shoals/nautical mile in December, respectively.
• Stable Bottom Detection and Optimum Bottom Offset for Echo Integration of Demersal Fish

  DooJin Hwang, Kohji Iida, Tohru Mukai

  Nippon Suisan Gakkaishi (Japanese Edition) 61 (1) 43 - 50 1349-998X 1995 [Not refereed][Not invited]
   

  This paper discusses methods for the stable bottom detection and the optimum bottom offset which enable to separate the fish echoes from the bottom echoes with echo integration of demersal fish. In preprocessing of the echo signal, the bottom detection has to be done stably against the fluctuation of echo level and the bottom offset has to be set to a minimum height such that near bottom fish echoes are included. Two methods of bottom detection, namely echo level threshold method and maximum echo slope method were compared and analyzed. The echo level method works well if the ideal threshold level was given but it sometimes misses the bottom because of the fluctuation of the echo. Another method to detect the bottom which uses maximum echo slope indicates the simple and stable bottom detection. In addition, the bottom offset has to be set near to the bottom but not to include the bottom echo. Optimum bottom offset should be set a few samples before the detected bottom echo which relates the beginning of pulse shape and acoustic beam pattern to the bottom feature. © 1995, The Japanese Society of Fisheries Science. All rights reserved.
• Diurnal Variation of Encaged Fish Echoes, and Estimation of Fish Tilt Angle Distribution

  MUKAI Tohru, IIDA Kohji

  Fisheries Science Japanese Society of Fisheries Science 61 (4) 647 - 652 0919-9268 1995 [Not refereed][Not invited]
   

  The diurnal variation of the dorsal aspect target strength of encaged fish was investigated, and an attempt was made to estimate the fish tilt angle distributions. The experiment was conducted at Lake Kuttara in Hokkaido. In this lake, kokanee Oncorhynchus nerka are the dominant species. The net cage was made of nylon monofilament, had a volume of approximately one cubic meter, and was nearly acoustically transparent. Five kokanees, caught by gill net, were released into the net cage. During the experiment periods, the net cage was kept at a depth of 10 m under the transducer which was driven by a 50 kHz transmitter. About 600 echoes from encaged fish occurring over a 24 hour period were measured and analyzed. The results obtained were as follows: 1) The shape of the dorsal aspect target strength probability density functions (PDFs) of encaged fish showed a large variation before and after sunrise and sunset. 2) Diurnal variation of the averaged dorsal aspect target strength of encaged fish was about 18 dB. 3) Some of the observed target strength PDFs agree approximately with estimated target strength PDFs based on fish tilt angle distribution which was assumed to truncated normal distribution.
• Behavior of Kokanee Oncorhynchus nerka in Lake Kuttara Observed by Echo Sounder

  IIDA Kohji, MUKAI Tohru

  Fisheries Science Japanese Society of Fisheries Science 61 (4) 641 - 646 0919-9268 1995 [Not refereed][Not invited]
   

  Acoustic surveys for studying the behavior of kokanee Oncorhynchus nerka in Lake Kuttara, Hokkaido, have been conducted over the past ten years and several interesting results have been obtained. Kokanee were recorded on echograms as school echoes in the daytime and as numerous individual echoes in the nighttime. Their swimming layer changes seasonally in accordance with the depth change of thermocline in the lake. Kokanee also have a diurnal behavioral pattern. Namely, they form schools after sunrise and they disperse after sunset. The shifting process from individuals to schools or from schools to individuals is strongly related to illuminance, and it takes 50 minutes at sunrise and sunset for the change to occur. The swimming speed of kokanee in the daytime is faster than that in the nighttime, and the fastest speed of the day occurs at twilight. Average swimming speeds were estimated to be 57 cm/s in the twilight, 48 cm/s in the daytime and 20 cm/s in the nighttime periods, respectively.
• 飼育下におけるスケトウダラの繁殖行動に伴う鳴音

  桜井 泰憲, 向井 徹, 朴 容石

  日本水産學會誌 日本水産學會 60 (4) 467 - 472 0021-5392 1994/07 [Not refereed][Not invited]
  
• Relation between Dorsal Aspect Target Strength of Fish Caught in the East China Sea and Their Swimbladder.

  Mukai Tohru, Sano Noritatsu, Iida Kohji, Sasaki Seiji

  NIPPON SUISAN GAKKAISHI 日本水産學會 60 (2) 215 - 222 0021-5392 1994 [Not refereed][Not invited]
   

  The target strength (TS) of fish varies with acoustic frequency, fish size, fish activity, orientation, swimbladder and so on. Among these, the swimbladder is recognized as having the most important effect on TS. The dorsal aspect TS as a function of tilt angle of fish caught by bottom trawling in the East China Sea was measured at two frequencies (25 and 100 kHz). The swimbladder sizes (length and height) and inclination angle of the swimbladder to the lateral line of the fish were measured by X-ray photographs. TS and swimbladder data were then compared and analyzed, and the following results were obtained:
  (1) The eight species of fish, except the silver pomfret, have swimbladders, but the angle and size of the swimbladder varies.
  (2) For bladder fish, the angle of the maximum dorsal aspect TS agrees with the broadside direction of the swimbladder.
  (3) The dorsal aspect TS of the silver pomfret is clearly lower than that of bladder fish at the two frequencies.
  (4) The maximum and averaged dorsal aspect TS values of the silver pomfret, were lower by about 7-8 dB, 8-10 dB at 25 kHz, and by 8-10 dB, 9-11 dB at 100 kHz than two other bladder fish (yellow sea bream and whitefin crevalle).
• Measurement of Dorsal Aspect Target Strength of Live Swimming Crab Portunus trituberculatus Caught in the East China Sea.

  Mukai Tohru, Sano Noritatsu, Iida Kohji, Sasaki Seiji

  NIPPON SUISAN GAKKAISHI 日本水産學會 60 (2) 223 - 227 0021-5392 1994 [Not refereed][Not invited]
   

  The dorsal aspect target strength (TS) of four live swimming crab Portunus trituberculatus were measured at 25kHz and 100kHz in Cheju port (Korea). Probability density functions (PDF), i.e., Rayleigh PDF and Rice PDF, were fitted to the distribution of backscattering amplitude from the live swimming crab. The following results were obtained:
  (1) TS was more dispersed at 100kHz than at 25kHz.
  (2) The PDFs of the backscattering amplitude agree approximately with Rice PDF at 25kHz and with Rayleigh PDF at 100kHz.
  (3) The Rice parameter γ tends to decrease with increasing carapace length, carapace width and acoustic frequency.
  (4) The averaged TS , estimated from PDFs, is about 2dB higher at 25kHz than at 100kHz.
  (5) Mean values of averaged target strength B, which is normalized with respect to body weight, are -52.5dB at 25kHz, -54.9dB at 100kHz. These values agree approximately with those of bladder fish.
• Sound Production Related to the Reproductive Behavior of Captive Walleye Pollock Theragra chalcogramma (Pallas)

  Yong-Seok Park, Yasunori Sakurai, Tohru Mukai, Kohji Iida, Noritatsu Sano

  NIPPON SUISAN GAKKAISHI 60 (4) 467 - 472 1349-998X 1994 [Not refereed][Not invited]
   

  In the spawing season, sound production of captive walleye pollock Theragra chalcogramma (Pallas) was examined by the grunt call projection method. The pollock emitted four patterns of grunt calls, namely threatening call, aggressive-attacking call, courting call, and mating call. The sound frequency of these grunt calls is less than 800 Hz. The characteristics of walleye pollock behaviour matching each grunt call are as follows: (1) Only one threatening grunt call was emitted by the superior male to threaten other males encountered. (2) Aggressive-attacking grunt calls were emitted from two to five times in order to drive out other males from the male's occupied space. Behaviour included chasing, dorsal mounting and lateral mounting. (3) Courting calls were emitted from six to twelve times in order to court other males and females which are characterized by swimming faster than usual. The behaviour included chasing, dorsal mounting and lateral mounting. (4) Mating grunt calls were made more than thirteen times in order to mate with mature females. Behaviour included chasing, and dorsal, lateral and ventral mounting. © 1994, The Japanese Society of Fisheries Science. All rights reserved.
• Sound Production Related to the Reproductive Behavior of Captive Walleye Pollock Theragra chalcogramma (Pallas).

  Park Yong-Seok, Sakurai Yasunori, Mukai Tohru, Iida Kohji, Sano Noritatsu

  NIPPON SUISAN GAKKAISHI 日本水産學會 60 (4) 467 - 472 0021-5392 1994 [Not refereed][Not invited]
   

  In the spawing season, sound production of captive walleye pollock Theragra chalcogramma (Pallas) was examined by the grunt call projection method. The pollock emitted four patterns of grunt calls, namely threatening call, aggressive-attacking call, courting call, and mating call. The sound frequency of these grunt calls is less than 800 Hz. The characteristics of walleye pollock behaviour matching each grunt call are as follows:
  (1) Only one threatening grunt call was emitted by the superior male to threaten other males encountered.
  (2) Aggressive-attacking grunt calls were emitted from two to five times in order to drive out other males from the male's occupied space. Behaviour included chasing, dorsal mounting and lateral mounting.
  (3) Courting calls were emitted from six to twelve times in order to court other males and females which are characterized by swimming faster than usual. The behaviour included chasing, dorsal mounting and lateral mounting.
  (4) Mating grunt calls were made more than thirteen times in order to mate with mature females. Behaviour included chasing, and dorsal, lateral and ventral mounting.
• エコー積分とトロールデータから算出した東シナ海における底棲魚族のターゲットストレングスについて

  黄 斗湊, 佐野 典達, 飯田 浩二, 向井 徹, 増田 紀義, 佐々木 成二

  北海道大學水産學部研究彙報 北海道大学 44 (4) 197 - 208 0018-3458 1993/11 [Not refereed][Not invited]
  
• Studies on Dorsal Aspect Target Strength of Ten Species of Fish Collected in the East China Sea.

  Mukai Tohru, Sano Noritatsu, Iida Kohji, Sasaki Seiji

  NIPPON SUISAN GAKKAISHI 日本水産學會 59 (9) 1515 - 1525 0021-5392 1993 [Not refereed][Not invited]
   

  The dorsal aspect target strength functions of ten species of fish collected by bottom trawl were measured at two frequencies. The average TS were calculated with respect to fish tilt angle distribution, which is assumed to have a mean value of -5 degrees and a standard deviation of 15 degrees. Both maximum TS and average TS were normalized with the fish length (L[cm]) squared and the 2/3 power of body weight (W[g]), namely,
  TS=20logL+A, TS=20/3log W+B.
  The results obtained were as follows:
  (1) The target strength is generally higher at low frequency (25kHz) than at high frequency (100kHz). But for two species (Chub mackerel and Kandari), neither maximum nor average TS differ between low and high frequencies.
  (2) The target strength of Silver pomfret, a bladderless fish, is clearly lower than that of bladder fish at two frequencies.
  (3) The normalized TS (A or B) were calculated for the maximum TS (A_max or B_max) and average TS (A_avg or B_avg). The results are: A_max = -63 - -59 dB, A_avg = -68 - -64 dB at low frequency; A_max = -65 - -59 dB, A_avg = -72 - -65 dB at high frequency, and B_max = -52 - -45 dB, B_avg = -57 - -50 dB at low frequency; B_max = -54 - -45 dB, B_avg = -60 - -52 dB at high frequency.
• Diurnal Variation of Encaged Fish Echoes

  MUKAI T.

  Bulletin of the Faculty of Fisheries,Hokkaido University 北海道大學水産學部 42 (3) p90 - 97 0018-3458 1991/08 [Not refereed][Not invited]
  
• Application of a dual beam echo sounder to measuring fish length.

  Iida Kohji, Mukai Tohru, Ishii Kiyohiko

  NIPPON SUISAN GAKKAISHI 日本水産學會 57 (4) 623 - 627 0021-5392 1991 [Not refereed][Not invited]
   

  This paper discusses the application of a dual beam echo sounder to the estimation of fish length.
  The dual beam method is typically used for measurement of the in situ target strength of fish. The in situ target strength is an important parameter, not only for obtaining the echo integrator scaling factor but also for estimating the fish length that is related to target strength.
  A prototype dual beam echo sounder system with computer technology was developed and used in the acoustic survey conducted at Lake Kuttara. Kokanee Oncorhynchus nerka is abundant in this lake.
  Many individual echoes were recorded using the dual beam echo sounder and target strength data were collected.
  Converting target strength, TS, into body length, l, was done using the following relational formula:
  TS(dB)=20logl(cm)-66.0
  Results of the analysis indicated that both the distributions of target strength and body length which were estimated by the dual beam method agreed to the catch data obtained from net sampling.
• Acoustic Estimation of Fish Length Distribution Using a Dual Beam Method

  飯田 浩二, 向井 徹, 石井 清彦

  Bulletin of the Faculty of Fisheries,Hokkaido University 北海道大學水産學部 41 (4) p200 - 204 0018-3458 1990/11 [Not refereed][Not invited]
  
• Notes on Body Length and Growth of Scales on the Kokanee Salmon, Oncorhynchus nerka (Walbaum), in Lake Kuttara, Hokkaido

  石井 清彦, 飯田 浩二, 向井 徹

  Bulletin of the Faculty of Fisheries,Hokkaido University 北海道大學水産學部 40 (4) p307 - 312 0018-3458 1989/11 [Not refereed][Not invited]
  
• The Effect of Swimbladder on Target Strength of Kokanee (Oncorhynchus nerka f. adonis)

  MUKAI Tohru, SUZUKI Tsuneyoshi, SANO Noritatsu, IIDA Kohji

  Bulletin of the Faculty of Fisheries,Hokkaido University 北海道大學水産學部 39 (2) p106 - 114 0018-3458 1988/05 [Not refereed][Not invited]
  

Conference Activities & Talks

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  山口篤, 松石隆, 向井徹, 藤森康澄, 別府史章, 細川雅史

  日本ベントス学会・日本プランクトン学会合同大会講演要旨集  2021
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  藤貫雅礼, 向井徹, 長谷川浩平, 福田美亮, 閻乃筝

  日本水産学会大会講演要旨集(CD-ROM)  2021
• Development of the target strength measuring system using the acrylic water tank.

  福田美亮, 長谷川浩平, 向井徹, 今泉智人

  海洋音響学会研究発表会講演論文集  2021
• Wideband target strength characteristics of bladderless fishes with different body shapes

  YAN Naizheng, 向井徹, 長谷川浩平, 山本潤, 福田美亮

  海洋音響学会研究発表会講演論文集  2021
• Broadband side-aspect target strength of Japanese jack mackerel and chub mackerel

  池田大典, 長谷川浩平, 向井徹, 福田美亮, YAN Naizheng

  海洋音響学会研究発表会講演論文集  2021
• 黒潮親潮混合域における高気圧性渦の一次生産と魚類分布への影響

  土橋稜, 上野洋路, 加藤陸, 閻乃筝, 向井徹, 安間洋樹, 野村大樹, 伊藤幸彦, 笠井亮秀

  日本水産学会大会講演要旨集(CD-ROM)  2021
• 動物プランクトンのTS推定に必要な形状パラメータの自動計測

  斉書豪, 福田美亮, 長谷川浩平, 閻乃筝, 向井徹

  日本水産学会大会講演要旨集(CD-ROM)  2021
• 全周ソナーを用いた北海道釧路沖におけるサバ類・マイワシの魚群形状の測定

  川添祐斗, 長谷川浩平, 福田美亮, 閻乃筝, 向井徹, 山口浩志, 守田航大

  日本水産学会大会講演要旨集(CD-ROM)  2021
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  山口篤, 松石隆, 向井徹, 藤森康澄, 別府史章, 細川雅史

  日本水産学会北海道支部大会講演要旨集  2020
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  工藤尚之, 向井徹, 長谷川浩平, 閻乃筝, 大西由利子, 笠井昭範, 西山義浩, 山本潤

  日本水産学会大会講演要旨集  2019/03
• 音響手法を用いたスケトウダラ稚魚に対するフレーム型中層トロール(FMT)の採集効率の昼夜比較  [Not invited]

  呂振, 向井徹, 藤森康澄, 飯田浩二, 長谷川浩平

  日本水産学会大会講演要旨集  2019/03
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  松裏知彦, 澤田浩一, 今泉智人, 長谷川浩平, 向井徹

  日本水産学会大会講演要旨集  2019/03
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  小川孝臣, 向井徹, 長谷川浩平, 石川加奈子, 永田貴丸

  日本水産学会大会講演要旨集  2019/03
• 20190701  [Not invited]

  KURODA Masao, UCHIYAMA Masaki, AZUMA Takahumi, UCHIDA Keiichi, TOKAI Tadashi, MUKAI Tooru, IMASATO Yoshinori, MORII Yasuhiro, YAGI Mitsuharu, SIMIZU Ken-ichi, MITSUHASHI Nobuo

  Proceedings of Annual Meeting of the Japanese Society of Fisheries Engineering  2019  The Japanese Society of Fisheries Engineering
  
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  山口卓也, 磯田豊, 向井徹, 小林直人

  日本海洋学会大会講演要旨集  2018/09
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  橋本康平, 向井徹, 飯田浩二, 澤田浩一, 石川可奈子

  日本水産学会大会講演要旨集  2018/03
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  都築佳代子, 向井徹, 甘糟和男, 山本潤

  日本水産学会大会講演要旨集  2018/03
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  閻乃筝, 向井徹, 山本潤

  日本水産学会大会講演要旨集  2018/03
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  鈴木孝太, 高津哲也, 中脇鴻陽, 武藤卓志, 向井徹, 藤森康澄, 中屋光裕

  日本魚類学会年会講演要旨  2017/09
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  長谷川浩平, 澤田浩一, 松裏知彦, 向井徹

  日本水産学会大会講演要旨集  2017/03
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  日本水産学会大会講演要旨集  2017/03
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  久保田大智, 飯田浩二, 向井徹, 貞安一廣, 今泉智人

  日本水産学会大会講演要旨集  2017/03
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  呂振, 飯田浩二, 向井徹

  日本水産学会大会講演要旨集  2017/03
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  閻乃筝, 向井徹, 山本潤

  日本水産学会北海道支部大会講演要旨集  2016/10
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  甘糟和男, 向井徹, 茂木正人, 茂木正人

  海洋音響学会研究発表会講演論文集  2016/05
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  辺見智佳子, 工藤大暉, 林宥樹, 甘糟和男, 真壁竜介, 向井徹, 茂木正人, 茂木正人

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  海洋音響学会研究発表会講演論文集  2016/05
• 広帯域音響信号で測定したスケトウダラ稚魚のターゲットストレングスと尾叉長の関係  [Not invited]

  林宥樹, 向井徹, 甘糟和男, 山本潤, 飯田浩二

  海洋音響学会研究発表会講演論文集  2016/05
• 広帯域音波を用いたスケトウダラ稚魚のターゲットストレングス測定  [Not invited]

  林宥樹, 向井徹, 甘糟和男, 山本潤, 飯田浩二

  日本水産学会大会講演要旨集  2016/03
• 道東沖における中深層性マイクロネクトンの種・体長組成別の音響データセット構築  [Not invited]

  松裏知彦, 澤田浩一, 福田美亮, 向井徹

  日本水産学会大会講演要旨集  2016/03
• J‐QUESTχを用いた道東沖におけるトドハダカの自然状態ターゲットストレングス測定  [Not invited]

  澤田浩一, 松裏知彦, 福田美亮, 向井徹

  日本水産学会大会講演要旨集  2016/03
• フレームトロール(FMT)によるスケトウダラ稚魚採集における網地色の影響  [Not invited]

  田谷惣一郎, 藤森康澄, 向井徹, 清水晋

  日本水産学会大会講演要旨集  2014/09
• リニアFM信号を用いた水中物体の広帯域ターゲットストレングス測定  [Not invited]

  三好寿郎, 飯田浩二, 向井徹

  日本水産学会大会講演要旨集  2014/03
• 淡水中での活イカのターゲットストレングス測定  [Not invited]

  山口柊, 向井徹, 山本潤, 柳海均, 飯田浩二

  日本水産学会大会講演要旨集  2014/03
• 大型クラゲNemopilema nomuraiの音響調査手法  [Not invited]

  広瀬美由紀, 向井徹

  日本水産学会大会講演要旨集  2014/03
• 多周波音響プロファイラーによる大型動物プランクトン来遊検知  [Not invited]

  澤田浩一, 向井徹, 安部幸樹, 松裏知彦, 黒川忠英

  日本水産学会大会講演要旨集  2014/03
• ツノナシオキアミの平均ターゲットストレングス推定に必要な遊泳姿勢角の測定  [Not invited]

  古川渉, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2014/03
• 計量ソナーを用いた魚の姿勢分布推定と魚群量推定への応用  [Not invited]

  高橋竜三, 向井徹, 西森靖, 飯田浩二

  日本水産学会大会講演要旨集  2014/03
• 計量魚探機を用いた北海道オホーツク海におけるスケトウダラとオキアミ類の分布特性  [Not invited]

  水上卓哉, 板谷和彦, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2014/03
• 音響手法を用いた北海道噴火湾周辺海域における動物プランクトンの消長  [Not invited]

  金銀好, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2014/03
• 2周波差分法を用いたツノナシオキアミの生物量推定手法の検討  [Not invited]

  福嶋美帆, 福田美亮, 向井徹, 澤田浩一, 松裏知彦, 飯田浩二

  日本水産学会大会講演要旨集  2014/03
• 音響的手法を用いたオキアミ類に対するフレームトロールの採集効率の昼夜変動  [Not invited]

  呂振, 飯田浩二, 向井徹

  日本水産学会大会講演要旨集  2014/03
• 音響的手法によるプランクトンネットの採集効率の推定  [Not invited]

  呂振, 飯田浩二, 向井徹

  日本水産学会大会講演要旨集  2013/09
• 広帯域超音波を用いたツノナシオキアミの体長及び生物量推定のシミュレーション  [Not invited]

  福田美亮, 向井徹, 澤田浩一, 飯田浩二

  海洋音響学会研究発表会講演論文集  2013/05
• 計量魚探機で観測された北海道オホーツク海におけるスケトウダラとオキアミ類の日周鉛直移動  [Not invited]

  水上卓哉, 板谷和彦, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2013/03
• 標準球を用いた多周波音響プロファイラーAZFPの較正  [Not invited]

  松裏知彦, 澤田浩一, 向井徹

  日本水産学会大会講演要旨集  2013/03
• マアジ稚幼魚を対象とした表中層トロール調査における採集量の変動要因  [Not invited]

  小堺真理子, 志村健, 藤森康澄, 向井徹

  日本水産学会大会講演要旨集  2013/03
• 2周波差分法を用いた道東沖太平洋における動物プランクトンの生物量推定  [Not invited]

  福嶋美帆, 福田美亮, 向井徹, 澤田浩一, 松裏知彦, 飯田浩二

  日本水産学会大会講演要旨集  2013/03
• 広帯域エコーから求める体積散乱強度  [Not invited]

  甘糟和男, 福田美亮, 向井徹

  日本水産学会大会講演要旨集  2013/03
• 多周波音響プロファイラーを用いた動物プランクトンの長期連続モニタリング  [Not invited]

  澤田浩一, 松裏知彦, 安部幸樹, 向井徹

  日本水産学会大会講演要旨集  2013/03
• 北海道噴火湾におけるツノナシオキアミの音速比,密度比測定とターゲットストレングス推定  [Not invited]

  福田美亮, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2013/03
• 大型動物プランクトンに対する人工照明を用いた鉛直曳網採集具の採集能力  [Not invited]

  金銀好, 向井徹, 藤森康澄, 飯田浩二

  日本水産学会大会講演要旨集  2012/09
• ハタハタ稚魚の理論モデルによるターゲットストレングス推定  [Not invited]

  松倉隆一, 古仲博, 甲本亮太, 山田達哉, 藤原邦浩, 向井徹

  日本水産学会大会講演要旨集  2012/09
• クラゲの形状変化に伴う音響散乱特性  [Not invited]

  広瀬美由紀, 向井徹, 福田美亮, 澤田浩一

  海洋音響学会研究発表会講演論文集  2012/05
• 高周波広帯域超音波を用いたツノナシオキアミのターゲットストレングス測定  [Not invited]

  福田美亮, 向井徹, 澤田浩一, 飯田浩二

  海洋音響学会研究発表会講演論文集  2012/05
• 超音波診断装置を用いた海洋生物の体内組織について  [Not invited]

  森本敦也, 飯田浩二, 向井徹

  海洋音響学会研究発表会講演論文集  2012/05
• 統計的手法による音響散乱層構成生物のターゲットストレングスの推定  [Not invited]

  LU Zhen, 飯田浩二, 向井徹

  海洋音響学会研究発表会講演論文集  2012/05
• 2周波数差法を用いたオキアミの生物密度の推定について  [Not invited]

  LEE Kyounghoon, 向井徹

  海洋音響学会研究発表会講演論文集  2012/05
• 超広帯域送受波器を使用した音響散乱スペクトルの測定  [Not invited]

  甘糟和男, 湯川智弘, 三島由夏, 向井徹, 澤田浩一, 笹倉豊喜

  海洋音響学会研究発表会講演論文集  2012/05
• 北海道釧路沖におけるツノナシオキアミの音速比,密度比測定とターゲットストレングス推定  [Not invited]

  福田美亮, 向井徹, 澤田浩一, 松裏知彦, 飯田浩二

  日本水産学会大会講演要旨集  2012/03
• 統計的手法による音響散乱層構成生物のターゲットストレングスの推定  [Not invited]

  呂振, 飯田浩二, 向井徹

  日本水産学会大会講演要旨集  2012/03
• 北海道釧路沖におけるツノナシオキアミの日中の分布深度と光との関係  [Not invited]

  松裏知彦, 澤田浩一, 内川和久, 福田美亮, 向井徹

  日本水産学会大会講演要旨集  2012/03
• 計量ソナーによる音響調査に必要なマアジの3次元ターゲットストレングス測定  [Not invited]

  鶴田直剛, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2012/03
• Acoustic Characteristics of Nemopilema nomurai  [Not invited]

  広瀬 美由紀, 黄 斗湊, 向井 徹

  海洋音響学会誌  2012/01
• 積層圧電素子を使用した広帯域送受波器による測定実験  [Not invited]

  甘糟和男, 三島由夏, 宮城亜紀, 向井徹, 澤田浩一, 笹倉豊喜

  日本水産学会大会講演要旨集  2011/09
• 超広帯域送受波器の試作  [Not invited]

  三島由夏, 甘糟和男, 澤田浩一, 向井徹, 笹倉豊喜

  海洋音響学会研究発表会講演論文集  2011/05
• 広帯域超音波を用いた動物プランクトンのターゲットストレングス測定  [Not invited]

  福田美亮, 向井徹, 澤田浩一, 飯田浩二

  海洋音響学会研究発表会講演論文集  2011/05
• 遊泳姿勢に伴うミズクラゲの音響散乱特性  [Not invited]

  広瀬美由紀, 向井徹, 福田美亮, 澤田浩一

  海洋音響学会研究発表会講演論文集  2011/05
• カイアシ類の音響資源調査の実現へ向けて―ターゲットストレングスの実測―  [Not invited]

  黒川有希子, 向井徹, 澤田浩一, 福田美亮, 飯田浩二

  日本水産学会大会講演要旨集  2011/03
• 北海道釧路沖および北西太平洋外洋域における動物プランクトンの音速比,密度比測定  [Not invited]

  福田美亮, 澤田浩一, 杉崎宏哉, 渡邉光, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2011/03
• 積層圧電素子を使用した広帯域送受波器  [Not invited]

  甘糟和男, 笹倉豊喜, 三島由夏, 澤田浩一, 向井徹

  日本水産学会大会講演要旨集  2011/03
• 動物プランクトンの音響調査に必要なターゲットストレングス(TS)推定  [Not invited]

  向井徹, 澤田浩一, 福田美亮, 黒川有希子, 飯田浩二

  海洋工学シンポジウム(CD-ROM)  2011
• 計量ソナーを用いた魚群の散乱強度の指向性の解析と散乱モデルによる遊泳姿勢分布推定について  [Not invited]

  高橋竜三, 向井徹, 西森靖, 飯田浩二

  日本水産学会大会講演要旨集  2010/09
• 超広帯域送受波器の設計手法と試作  [Not invited]

  笹倉豊喜, 甘糟和男, 澤田浩一, 向井徹

  日本水産学会大会講演要旨集  2010/09
• オキアミ採集における人工照明の効果  [Not invited]

  坂口旭, 藤森康澄, 向井徹, 木村暢夫

  日本水産学会大会講演要旨集  2010/09
• 噴火湾湾外部に生息する動物プランクトンのターゲットストレングス測定―タンキャク類,ヤムシ類―  [Not invited]

  福田美亮, 向井徹, 澤田浩一, 黒川有希子, 飯田浩二

  日本水産学会大会講演要旨集  2010/09
• 姿勢変化に伴うエチゼンクラゲ(Nemopilema nomurai)の音響散乱特性  [Not invited]

  広瀬美由紀, 向井徹, HWANG Doo‐Jin

  海洋音響学会研究発表会講演論文集  2010/05
• Optimal Fish Target Strength for Detecting Fish School using Horizontal Echosounder  [Not invited]

  KURNIA MUHAMMAD, IIDA KOHJI, MUKAI TOHRU

  超音波エレクトロニクスの基礎と応用に関するシンポジウム講演予稿集  2009/11
• 2E6-1 Optimal Fish Target Strength for Detecting Fish School using Horizontal Echosounder(Oral Session in English III)  [Not invited]

  Kurnia Muhammad, Iida Kohji, Mukai Tohru

  Symposium on ultrasonic electronics  2009/11
• 2周波数を用いて水槽および現場で測定されたマアジ幼魚の音響特性  [Not invited]

  塩田理絵, 志村健, 安部幸樹, 向井徹, 飯田浩二

  海洋音響学会研究発表会講演論文集  2009/05
• ミズクラゲのターゲットストレングス―拍動および姿勢による変化―  [Not invited]

  向井徹, 広瀬美由紀, 澤田浩一, 高橋春香, 飯田浩二

  海洋音響学会研究発表会講演論文集  2009/05
• 音響散乱モデルによるカイアシ類のターゲットストレングス推定  [Not invited]

  黒川有希子, 向井徹, 澤田浩一, 福田美亮, 飯田浩二

  海洋音響学会研究発表会講演論文集  2009/05
• 計量スキャニングソナーを用いた魚群の反射強度の指向性と魚群行動について  [Not invited]

  高橋竜三, 向井徹, 西森靖, 飯田浩二

  海洋音響学会研究発表会講演論文集  2009/05
• オキアミ類,カイアシ類,タンキャク類に対するLOPCの計測特性  [Not invited]

  山下由起子, 藤森康澄, 向井徹, 木村暢夫

  日本水産学会大会講演要旨集  2009/03
• 隠岐諸島周辺海域におけるマアジ幼魚の音響調査‐2 周波数による音響特性‐  [Not invited]

  塩田理絵, 向井徹, 志村健, 飯田浩二

  日本水産学会大会講演要旨集  2009/03
• 音響資源調査のためのオキアミ類のターゲットストレングス推定プロジェクト VI―背方向TSの体長依存性と周波数特性―  [Not invited]

  福田美亮, 向井徹, 澤田浩一, 石井憲, 飯田浩二

  日本水産学会大会講演要旨集  2009/03
• 計量スキャニングソナーを用いた魚群への音波の入射角の違いによる散乱強度の変化と魚群の遊泳方向の関係について  [Not invited]

  高橋竜三, 向井徹, 西森靖, 飯田浩二

  日本水産学会大会講演要旨集  2009/03
• マアジのターゲットストレングスと鰾の関係  [Not invited]

  安部幸樹, 志村健, 塩田理絵, 福田美亮, 向井徹, 澤田浩一, 石井憲

  日本水産学会大会講演要旨集  2009/03
• 音響散乱モデルを用いたカイアシ類のターゲットストレングス推定に必要な音速比と密度比の測定  [Not invited]

  黒川有希子, 向井徹, 福田美亮, 飯田浩二

  日本水産学会大会講演要旨集  2009/03
• 拍動および超音波入射角の変化によるミズクラゲのターゲットストレングスの変化  [Not invited]

  向井徹, 広瀬美由紀, 澤田浩一, 石井憲, 高橋春香, 飯田浩二

  日本水産学会大会講演要旨集  2009/03
• Omni-directional target strength measurement of Japanese horse mackerel (Trachurus japonicus) using horizontal echosounder  [Not invited]

  KURNIA MUHAMMAD, IIDA KOHJI, MUKAI TOHRU

  日本水産学会北海道支部大会講演要旨集  2009
• 音響資源調査による最近5年間の道南太平洋スケトウダラ資源と海洋環境の関係について  [Not invited]

  飯田浩二, 楊涵森, 向井徹

  日本水産学会北海道支部大会講演要旨集  2009
• 水中音響カメラの分解能測定  [Not invited]

  河田悠, 飯田浩二, 向井徹

  日本水産学会北海道支部大会講演要旨集  2009
• 噴火湾湾外部におけるカイアシ類の音速比と密度比の変化  [Not invited]

  黒川有希子, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  2009
• 計量スキャニングソナーで計測された魚群反射強度の指向性と魚群の遊泳方向の関係について  [Not invited]

  高橋竜三, 飯田浩二, 西森靖, 向井徹

  日本水産学会北海道支部大会講演要旨集  2009
• 北海道噴火湾における音響散乱層の日周鉛直移動と照度の関係  [Not invited]

  出縄萌, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  2009
• Omnidirectional target strength of Horse mackerel (Trachurus japonicus) for sonar survey  [Not invited]

  KURNIA MUHAMMAD, IIDA KOHJI, MUKAI TOHRU

  海洋音響学会研究発表会講演論文集  2008/05
• クラゲ類の体内音速および生体密度―エチゼンクラゲ,ミズクラゲ,ユウレイクラゲ―  [Not invited]

  広瀬美由紀, 向井徹, 飯田浩二, 飯泉仁

  海洋音響学会研究発表会講演論文集  2008/05
• マアジ幼魚のターゲットストレングス測定  [Not invited]

  安部幸樹, 志村健, 澤田浩一, 貞安一廣, 福田美亮, 塩田理絵, 向井徹, 石井憲

  日本水産学会大会講演要旨集  2008/03
• カイアシ類のターゲットストレングス測定 I―測定システムの設計手法の開発―  [Not invited]

  澤田浩一, 石井憲, 福田美亮, 向井徹

  日本水産学会大会講演要旨集  2008/03
• カイアシ類のターゲットストレングス測定 II―120kHzにおけるTSの実測―  [Not invited]

  福田美亮, 向井徹, 澤田浩一, 塩田理絵, 石井憲, 内川和久, 飯田浩二

  日本水産学会大会講演要旨集  2008/03
• 音響散乱層の体積後方散乱強度の順方向推定による生物種別寄与率の検討  [Not invited]

  藤戸貴子, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2008/03
• ミズクラゲの生体内音速および生体密度  [Not invited]

  広瀬美由紀, 向井徹, 飯泉仁

  日本水産学会大会講演要旨集  2008/03
• Quantitative Multi-beam Sonar and Underwater Acoustic Camera for Fisheries Survey  [Not invited]

  IIDA KOHJI, MUKAI TOHRU, NISHIMORI YASUSHI, SATO MASANORI

  Program Abstr 5th World Fish Congr 2008  2008
• Three dimensional target strength of fish for resource survey using multibeam sonar  [Not invited]

  KURNIA MUHAMMAD, IIDA KOHJI, MUKAI TOHRU

  Program Abstr 5th World Fish Congr 2008  2008
• 3-11P-57 Interactive Analysis in Target Strength (TS) Pattern Measurements of Small Aquatic Organism(Poster session 3)  [Not invited]

  Ishii Ken, Abe Koki, Sawada Kouichi, Amakasu Kazuo, Mukai Tohru

  Proceedings of Symposium on Ultrasonic Electronics  2007/11
• 音響資源調査のためのオキアミ類のターゲットストレングス推定プロジェクト V―120kHzにおけるTSの実測―  [Not invited]

  福田美亮, 向井徹, 澤田浩一, 塩田理絵, 安部幸樹, 内川和久, 石井憲, 飯田浩二

  日本水産学会大会講演要旨集  2007/09
• 北海道噴火湾湾外部における動物プランクトンの体積後方散乱強度の順方向推定  [Not invited]

  藤戸貴子, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2007/09
• 音響資源調査のためのオキアミ類のターゲットストレングス推定プロジェクト IV―120kHz測定システムの構築―  [Not invited]

  澤田浩一, 石井憲, 安部幸樹, 向井徹

  日本水産学会大会講演要旨集  2007/09
• 計量ソナー調査のためのカタクチイワシの斜め方向ターゲットストレングス測定  [Not invited]

  谷上俊介, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2007/09
• LOPCを用いた知床周辺海域における動物プランクトンの分布‐2  [Not invited]

  山下由起子, 菊地広子, 藤森康澄, 向井徹, 三浦汀介

  日本水産学会大会講演要旨集  2007/09
• 音響資源調査のためのオキアミ類のターゲットストレングス推定プロジェクト II―精密測定による理論モデルの検証―  [Not invited]

  澤田浩一, 甘糟和男, 向井徹, 安部幸樹, 石井憲

  日本水産学会大会講演要旨集  2007/03
• 計量ソナー調査のためのカタクチイワシの側面方向ターゲットストレングスの測定  [Not invited]

  谷上俊介, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2007/03
• 音響資源調査のためのオキアミ類のターゲットストレングス推定プロジェクト III―体長と平均TSについて―  [Not invited]

  安部幸樹, 甘糟和男, 澤田浩一, 向井徹, 石井憲

  日本水産学会大会講演要旨集  2007/03
• 大型クラゲの音響散乱特性に関する研究  [Not invited]

  広瀬美由紀, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2007/03
• 音響資源調査のためのオキアミ類のターゲットストレングス推定プロジェクト I―目的と計画―  [Not invited]

  向井徹, 澤田浩一, 甘糟和男, 安部幸樹, 石井憲

  日本水産学会大会講演要旨集  2007/03
• トド幼獣の鳴音形成過程に関する研究  [Not invited]

  朴太健, 飯田浩二, 向井徹

  日本水産学会大会講演要旨集  2007/03
• LOPCを用いた知床周辺海域における動物プランクトンの分布  [Not invited]

  山下由起子, 小出正弘, 藤森康澄, 向井徹, 岩森利弘, 木村暢夫

  日本水産学会大会講演要旨集  2007/03
• カタクチイワシの背方向ターゲットストレングス測定  [Not invited]

  福田美亮, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2007/03
• 北海道知床沖における音響散乱層の観察と体積後方散乱強度について  [Not invited]

  藤戸貴子, 山本潤, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2007/03
• 制御法および音響散乱モデルによるカタクチイワシのターゲットストレングス推定  [Not invited]

  谷上 俊介, 福田 美亮, 向井 徹, 飯田 浩二

  日本水産工学会学術講演会講演論文集  2006/06
• 噴火湾におけるスケトウダラ分布のGIS解析  [Not invited]

  石原 俊輔, 向井 徹, 飯田 浩二

  日本水産工学会学術講演会講演論文集  2006/06
• 医療用超音波カメラによる魚体内部の音響画像の特徴  [Not invited]

  高橋 里佳, 飯田 浩二, 湯 勇, 向井 徹, 佐藤 正典

  日本水産工学会学術講演会講演論文集  2006/06
• 計量魚群探知機を用いた東シナ海における大型クラゲNemopilema nomuraiの音響調査  [Not invited]

  広瀬美由紀, 向井徹, 飯田浩二, 黄斗湊

  日本水産学会大会講演要旨集  2006/03
• 計量ソナーの開発と資源調査への応用 8.まき網漁業における計量ソナーの評価試験  [Not invited]

  飯田浩二, 湯勇, 金子武, 向井徹, 西森靖

  日本水産学会大会講演要旨集  2006/03
• 医療用超音波カメラを用いた魚類の内部形態計測  [Not invited]

  高橋里佳, 飯田浩二, 湯勇, 向井徹, 佐藤正典

  日本水産学会大会講演要旨集  2006/03
• ツノナシオキアミのターゲットストレングスの姿勢角特性の実測  [Not invited]

  甘糟和男, 向井徹, 沢田浩一, 石井憲, 安部幸樹, 高尾芳三

  日本水産学会大会講演要旨集  2006/03
• 計量ソナーにおけるターゲットストレングスの取扱い  [Not invited]

  向井徹

  日本水産学会大会講演要旨集  2006/03
• 計量ソナーの開発と資源調査への応用 9.幾何情報を用いたサバ,イナダ魚群の計測  [Not invited]

  湯勇, 飯田浩二, 向井徹, 西森靖

  日本水産学会大会講演要旨集  2006/03
• P2-44 Behavior of Marine Animals Using Underwater Acoustic Camera(Short oral presentation for posters)  [Not invited]

  IIDA Kohji, Tang Yong, MUKAI Tohru, Takahashi Rika, SATO Masanori

  Proceedings of Symposium on Ultrasonic Electronics  2005/11
• G-4 Measurement of Fish School Volume Using Omnidirectional Multi-Beam Sonar, -Scanning Mode and Algorithm-(Medical ultrasound, Underwater ultrasound)  [Not invited]

  Tang Yong, Iida Kohji, Mukai Tohru, Nishimori Yasushi

  Proceedings of Symposium on Ultrasonic Electronics  2005/11
• 医療用超音波カメラの魚類形態計測への応用  [Not invited]

  高橋里佳, 飯田浩二, TANG Yong, 向井徹, 佐藤正典

  超音波エレクトロニクスの基礎と応用に関するシンポジウム講演予稿集  2005/11
• P1-65 Application of ultrasonography for morphological measurement of marine fish  [Not invited]

  Takahashi Rika, Iida Kohji, Tang Yong, Mukai Tohru, Sato Masanori

  Proceedings of Symposium on Ultrasonic Electronics  2005/11
• WYSIWYG‐NETの開発 1.WYSIWYG‐NETプロジェクト  [Not invited]

  藤森康澄, 向井徹

  日本水産学会大会講演要旨集  2005/04
• 計量ソナーの開発と資源調査への応用 4.画像処理による魚群体積の推定  [Not invited]

  金子武, 湯勇, 飯田浩二, 向井徹, 西森靖

  日本水産学会大会講演要旨集  2005/04
• 計量ソナーの開発と資源調査への応用 1.計量ソナー研究の現状と課題  [Not invited]

  飯田浩二, 湯勇, 向井徹, 西森靖

  日本水産学会大会講演要旨集  2005/04
• 4.多段式フレームトロールの開発と動作試験  [Not invited]

  山下成治, 藤森康澄, 向井徹

  日本水産学会大会講演要旨集  2005/04
• 野生トドの鳴音の音響的特徴と体長との関係  [Not invited]

  小谷昇司, 朴太健, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2005/04
• エチゼンクラゲとユウレイレイクラゲの音響散乱特性の比較  [Not invited]

  広瀬美由紀, 向井徹, 黄斗湊, 飯田浩二

  日本水産学会大会講演要旨集  2005/04
• 北海道噴火湾における昼夜別スケトウダラ稚魚サンプリング  [Not invited]

  高草木将人, 山下由起子, 藤森康澄, 貞安一広, 向井徹, 三浦汀介

  日本水産学会大会講演要旨集  2005/04
• 計量ソナーの開発と資源調査への応用 5.水中バルーンを用いた体積推定法の評価試験  [Not invited]

  湯勇, 飯田浩二, 向井徹, 西森靖

  日本水産学会大会講演要旨集  2005/04
• 東西165度線における音響散乱層のSVについて―実測した密度比,音速比を用いた理論モデルからのアプローチ―  [Not invited]

  龍田隆明, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2005/04
• 2.LOPCの試験プラットフォーム  [Not invited]

  向井徹, 藤森康澄

  日本水産学会大会講演要旨集  2005/04
• 3.LOPCデータとネットサンプリングデータの比較・解析  [Not invited]

  岸淳一郎, 向井徹, 藤森康澄, 飯田浩二

  日本水産学会大会講演要旨集  2005/04
• 水中超音波カメラによる海洋生物の形態観察  [Not invited]

  飯田浩二, 湯勇, 向井徹, 高橋里佳, 佐藤正典

  日本水産学会大会講演要旨集  2005/04
• ソナグラムを用いたトド(Eumetopias jubatus)の鳴音の個体群間比較  [Not invited]

  朴太健, 飯田浩二, 向井徹, 小谷昇司

  日本動物行動学会大会発表要旨集  2005
• 魚類およびプランクトンの超音波反射特性に関する研究  [Not invited]

  向井徹

  日本水産学会大会講演要旨集  2004/03
• ADCPを用いた噴火湾における音響散乱層の鉛直移動の測定  [Not invited]

  李きょん勲, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2004/03
• 照度変化に伴うツノナシオキアミの遊泳姿勢およびターゲットストレングスの変化  [Not invited]

  牧陽一, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2004/03
• 計量ソナーによる水産資源調査法の課題  [Not invited]

  飯田浩二, 芳村康男, 向井徹, 康とん赫, 宮下和士

  日本水産学会大会講演要旨集  2004/03
• スケトウダラ稚魚のターゲットストレングス 2―成長とひょう形状の関係および音響理論モデルを用いた検証―  [Not invited]

  貞安一広, 安部幸樹, 沢田浩一, 石井憲, 高尾芳三, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2004/03
• エチゼンクラゲの音響散乱特性について  [Not invited]

  広瀬美由紀, 向井徹, 黄斗湊, 飯田浩二

  日本水産学会大会講演要旨集  2004/03
• 夏季ベーリング海における魚食性海鳥類の分布特性~音響調査による餌生物の分布との比較~  [Not invited]

  国分亙彦, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2004/03
• ＡＤＣＰによるＭＶＢＳのキャリブレーションの検討  [Not invited]

  海洋音響学会2004年度研究発表会講演論文集  2004
• Measurements on Sound Speed Contrast and Target Strength of Japanese Common Squid (Todarodes pacifica)  [Not invited]

  海洋音響学会2004年度研究発表会講演論文集  2004
• 遊泳による魚体の屈曲運動がターゲットストレングスに与える影響  [Not invited]

  海洋音響学会2004年度研究発表会講演論文集  2004
• Morphological Observation of Marine Organisms by Underwater Ultrasonography  [Not invited]

  Proceedings of the OCEANS 2004 MTS/IEEE. International Symposium, November 9-12, 2004  2004
• Acoustic Target Strength of Japanese Common Squid, Todarodes pacificus, and Important Parameters Influencing Its TS : Swimming Angle and Material Properties  [Not invited]

  Proceedings of the OCEANS 2004 MTS/IEEE. International Symposium, November 9-12, 2004  2004
• Measurement of Fish School Volume by Multi-beam Soner -Directional Resolution and Estimation Error-  [Not invited]

  Proceedings of the OCEANS 2004 MTS/IEEE. International Symposium, November 9-12, 2004  2004
• Measurements of Swimming Angles, Density, and Sound Speed of the Krill Euphausia Pacifica for Target Strength Estimation  [Not invited]

  Proceedings of the OCEANS 2004 MTS/IEEE. International Symposium, November 9-12, 2004  2004
• Estimation of the Variation in Target-Strength of Fish under Pressure Condition  [Not invited]

  Proceedings of the OCEANS 2004 MTS/IEEE. International Symposium, November 9-12, 2004  2004
• ネットサンプリングギアとLOPCによる動物プランクトンの同時観測  [Not invited]

  岸淳一郎, 山下由起子, 向井徹, 藤森康澄, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  2004
• 標本抽出率が採集生物の体長組成に与える影響  [Not invited]

  山下由起子, 藤森康澄, 向井徹, 清水晋, 三浦汀介

  日本水産学会北海道支部大会講演要旨集  2004
• 水中超音波カメラによる海洋生物の観察  [Not invited]

  飯田浩二, 湯勇, 向井徹, 佐藤正典

  日本水産学会北海道支部大会講演要旨集  2004
• 野生トドの鳴音の音響的特徴と体長との関係について  [Not invited]

  小谷昇司, 朴太健, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  2004
• 東西165度線における音響散乱層の生物密度と体積後方散乱強度の比較  [Not invited]

  龍田隆明, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  2004
• スキャニングソナーを用いた擬似魚群の体積測定  [Not invited]

  金子武, 湯勇, 飯田浩二, 向井徹, 西森靖

  日本水産学会北海道支部大会講演要旨集  2004
• 懸垂法によるエチゼンクラゲ(Stomolophus nomurai)のターゲットストレングス測定  [Not invited]

  広瀬美由紀, 向井徹, 黄斗湊, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  2003/11
• 計量魚探を用いた噴火湾湾外部におけるスケトウダラ魚群分布と海洋環境の関係について  [Not invited]

  甲斐匡, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  2003/11
• 照度変化によるツノナシオキアミのターゲットストレングスの変動  [Not invited]

  牧陽一, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  2003/11
• 懸垂法によるウスメバルとクロダイのターゲットストレングス測定における気泡の影響  [Not invited]

  貞安一広, 沢田浩一, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2003/04
• ADCPおよび計量魚探による音響散乱層の平均体積後方散乱強度(MVBS)の比較  [Not invited]

  李けい勲, 向井徹, 康とん赫, 飯田浩二

  日本水産学会大会講演要旨集  2003/04
• プランクトン・マイクロネクトンを対象としたWYSIWYG‐NETの開発 1. WYSIWYG‐NETの目指すところ  [Not invited]

  藤森康澄, 向井徹

  日本水産学会大会講演要旨集  2003/04
• プランクトン・マイクロネクトンを対象としたWYSIWYG‐NETの開発 3. D‐FMTによる採集生物と計量魚探データとの比較  [Not invited]

  加藤薫, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2003/04
• Ex situ target strength measurement and acoustic scattering model on Black porgy.  [Not invited]

  KO TONKAKU, SADAYASU KAZUHIRO, MUKAI TOORU, O TOSO, SAWADA KOICHI, IIDA KOJI

  日本水産学会大会講演要旨集  2003/04
• ドップラー流速計(ADCP)を用いた音響散乱層の生物密度推定方法について  [Not invited]

  李どう勲, 飯田浩二, 向井徹

  日本水産学会北海道支部大会講演要旨集  2002/11
• 科学魚探を用いた道南太平洋のスケトウダラ魚群分布と海洋環境の関係について  [Not invited]

  甲斐匡, 飯田浩二, 向井徹

  日本水産学会北海道支部大会講演要旨集  2002/11
• 飼育下のトド(Eumetopias jubatus)の鳴音と行動について  [Not invited]

  朴太健, 飯田浩二, 向井徹

  日本水産学会北海道支部大会講演要旨集  2002/11
• 懸垂法によるウスメバルのターゲットストレングス測定における気泡の影響について  [Not invited]

  貞安一広, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  2002/11
• ベーリング海におけるクラゲの音響探知の試み  [Not invited]

  広瀬美由紀, 飯田浩二, 向井徹

  日本水産学会北海道支部大会講演要旨集  2002/11
• 北部北太平洋における音響散乱層(SSL)の日周鉛直移動の地域特性  [Not invited]

  大西由利子, 飯田浩二, 向井徹

  日本水産学会北海道支部大会講演要旨集  2002/11
• 計量魚群探知機を用いた資源調査・研究の現状と課題 1. 計量魚群探知機とは  [Not invited]

  向井徹

  日本水産学会北海道支部大会講演要旨集  2002/11
• 淡水エビの理論TSと実測TSの比較  [Not invited]

  松倉隆一, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  2002/11
• 理論モデルを用いたTS推定に必要なツノナシオキアミの遊泳姿勢角の測定  [Not invited]

  牧陽一, 飯田浩二, 向井徹

  日本水産学会北海道支部大会講演要旨集  2002/11
• 道東太平洋におけるスケトウダラin situ TSの昼夜変動特性  [Not invited]

  安部幸樹, 本田聡, 大島達樹, 宮下和士, 飯田浩二, 向井徹

  日本水産学会大会講演要旨集  2002/03
• 水槽における自然法および制御法によるマサバとクロダイのターゲットストレングス測定  [Not invited]

  貞安一広, 向井徹, HWANG D, 沢田浩一, 飯田浩二

  日本水産学会大会講演要旨集  2002/03
• ビデオ信号を用いた活イカのターゲットストレングス測定  [Not invited]

  向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2002/03
• 日本海南西部における計量魚群探知機を用いた魚種判別の試み  [Not invited]

  藤野忠敬, 氏良介, 宮下和士, 鉄村光太郎, 山本潤, 増田紳哉, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2002/03
• スキャニングソーナーの画像処理による魚群量推定に関する研究  [Not invited]

  LEE Y‐W, 向井徹, 飯田浩二, 青木由直

  画像電子学会年次大会予稿集  2001/06
• スキャニングソーナーを用いた魚群量の定量化について  [Not invited]

  李遺元, 向井徹, 宮下和士, 飯田浩二

  日本水産学会大会講演要旨集  2001/04
• 特殊プラットフォームを用いたin situ TS測定の試み (2) エコートレースを用いたTS昼夜変動に関する考察  [Not invited]

  安部幸樹, 本田聡, 大島達樹, 宮下和士, 飯田浩二, 向井徹

  日本水産学会大会講演要旨集  2001/04
• 懸垂法による閉ひょう魚・開ひょう魚・無ひょう魚のターゲットストレングス測定  [Not invited]

  貞安一広, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2001/04
• 計量魚群探知機を用いた隠岐ノ島周辺海域の音響調査 エコーグラムを用いた魚種判別の試み  [Not invited]

  藤野忠敬, 氏良介, 宮下和士, 鉄村光太郎, 増田紳哉, 山本潤, 飯田浩二, 向井徹

  日本水産学会大会講演要旨集  2001/04
• 魚群探知機を用いた石狩川河口における遡上サケの行動調査について  [Not invited]

  飯田浩二, 向井徹, 李遺元, 貞安一広, 藤野忠敬, 浦野明央, 伴真俊

  日本水産学会大会講演要旨集  2001/04
• 制御法によるスケトウダラ幼稚魚のターゲットストレングスの測定  [Not invited]

  岡崎 亜美, 向井 徹, 飯田 浩二

  日本水産工学会学術講演会講演論文集  2000/06
• スキャニングソーナー映像を用いた魚群量の定量化の試み  [Not invited]

  李 遺元, 向井 徹, 飯田 浩二

  日本水産工学会学術講演会講演論文集  2000/06
• 衛星・音響・ROVリモートセンシングによる生物資源環境の多元計測とその応用  [Not invited]

  飯田浩二, 斉藤誠一, 桜井泰憲, 向井徹, 宮下和士, 藤森康澄, 甫喜本司, 山本潤, 山内こう平

  日本水産学会大会講演要旨集  2000/04
• 日本海スケトウダラ音響資源調査におけるトロールデータとin situ TSの比較  [Not invited]

  安部幸樹, 飯田浩二, 向井徹, 三宅博哉, 和田昭彦, 石田良太郎, 武藤卓志

  日本水産学会大会講演要旨集  2000/04
• ツノナシオキアミのTS推定に必要な生体密度と生体内音速の測定  [Not invited]

  三上尚之, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2000/04
• 制御法によるスケトウダラ稚魚のTS測定  [Not invited]

  岡崎亜美, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  2000/04
• 制御法による活スルメイカのターゲットストレングス測定  [Not invited]

  向井徹, 飯田浩二, 安部幸樹, 坂口健司

  日本水産学会大会講演要旨集  2000/04
• スキャニングソーナーによる表中層性魚群の船体逃避行動の観察  [Not invited]

  李遺元, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  1999/12
• ツノナシオキアミのTS推定に必要な密度比と音速比の測定  [Not invited]

  三上尚之, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  1999/12
• 恵山沖における音響散乱層のSVと種組成の季節的変化  [Not invited]

  荻野智志, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  1999/12
• 懸垂法とケージ法で測定した活イカのターゲットストレングス  [Not invited]

  向井徹, 飯田浩二, 安部幸樹, 坂口健司

  日本水産学会北海道支部大会講演要旨集  1999/12
• 懸垂した活スルメイカのスプリットビーム法によるTS測定  [Not invited]

  安部幸樹, 中田淳, 飯田浩二, 向井徹

  日本水産学会北海道支部大会講演要旨集  1999/12
• 衛星・音響・ROVリモートセンシングによる生物資源環境の多元計測とその応用  [Not invited]

  飯田浩二, 斉藤誠一, 桜井泰憲, 向井徹, 宮下和士, 藤森康澄, 甫喜本司, 山本潤, 山内こう平

  日本水産学会北海道支部大会講演要旨集  1999/12
• ゲージ法によるスケトウダラ稚魚のTS測定  [Not invited]

  岡崎亜美, 向井徹, 飯田浩二

  日本水産学会北海道支部大会講演要旨集  1999/12
• 稚魚のうきぶくろの形態と音響共振特性  [Not invited]

  飯田浩二, 向井徹

  日本水産学会大会講演要旨集  1999/04
• 計量魚群探知機EK‐500を用いた1998年日本海スケトウダラ資源調査  [Not invited]

  三宅博哉, 和田昭彦, 武藤卓志, 石田良太郎, 高柳志朗, 飯田浩二, 向井徹, 安部幸樹

  日本水産学会大会講演要旨集  1999/04
• ツノナシオキアミの理論散乱モデルにおける生体密度の測定について  [Not invited]

  三上尚之, 向井徹, 飯田浩二

  日本水産学会大会講演要旨集  1999/04
• 動物プランクトンのTS推定に必要な生体密度および生体内音速の測定  [Not invited]

  向井徹, CALISE L, FOOTE K G, KNUTSEN T

  日本水産学会大会講演要旨集  1999/04
• 理論散乱モデルを用いた動物プランクトンの個体数密度推定について  [Not invited]

  三上尚之, 飯田浩二, 向井徹

  日本水産学会大会講演要旨集  1998/09
• EK500で得られたスケトウダラin‐situTSのターゲットトラッキングアルゴリズムによる解析  [Not invited]

  安部幸樹, 飯田浩二, 向井徹, 三宅博哉

  日本水産学会大会講演要旨集  1998/09
• 道東太平洋のスケソウダラ音響資源量調査に関する空間統計手法適用についての考察  [Not invited]

  鈴木千洋, 飯田浩二, 向井徹

  日本水産学会大会講演要旨集  1998/09
• 有ひょう稚魚の音響共振散乱について  [Not invited]

  飯田浩二, 向井徹

  日本水産学会大会講演要旨集  1998/09
• Analysis of distribution and form of surface and midwater fish groups using scanning sonar.  [Not invited]

  HORIUCHI NORITAKA, IIDA KOJI, MUKAI TOORU

  日本水産学会大会講演要旨集  1998/04
• Single body detection capability of scientific fish finder EK500.  [Not invited]

  ABE KOKI, IIDA KOJI, MUKAI TOORU, MIYAKE HIROYA, KANEDA TOMONORI, MIZUNO MASAMI

  日本水産学会大会講演要旨集  1998/04
• Target strength of cods and sardines measured by the cage method.  [Not invited]

  MUKAI TOORU, IIDA KOJI

  日本水産学会大会講演要旨集  1998/04
• Calibration of measuring fish finder equipped to ship's bottom using calibration ball.  [Not invited]

  IIDA KOJI, MUKAI TOORU, MIYAKE HIROYA, MIHARA YUKIO, HONMA TAKAYUKI, TAKAYANAGI SHIRO

  日本水産学会大会講演要旨集  1998/04
• Characteristics of distribution of Alaska pollack in the west coast of Hokkaido.  [Not invited]

  MIYAKE HIROYA, KANEDA TOMONORI, MIZUNO MASAMI, TAKAYANAGI SHIRO, ISHIDA RYOTARO, MUTO TAKASHI, IIDA KOJI, MUKAI TOORU

  日本水産学会大会講演要旨集  1998/04
• Calibration of measure fish finder equipped in ship's bottom using calibration ball.  [Not invited]

  IIDA KOJI, MUKAI TOORU, MIYAKE HIROYA, MIHARA YUKIO, HONMA TAKAYUKI, TAKAYANAGI SHIRO

  日本水産学会北海道支部大会講演要旨集  1997/12
• Analysis of the shape and distribution of surface and middle layer fish group using the scanning sonar.  [Not invited]

  HORIUCHI NORITAKA, IIDA KOJI, MUKAI TOORU

  日本水産学会北海道支部大会講演要旨集  1997/12
• On the target strength of sardine and anchovy measured by the cage method.  [Not invited]

  MUKAI TOORU, IIDA KOJI

  日本水産学会北海道支部大会講演要旨集  1997/12
• Comparison of frequency characteristics of acoustic scattering layer in the Sea of Japan on west side of Hokkaido and Sanrikuoki observed with measure fish finder.  [Not invited]

  MORI HIDEKI, IIDA KOJI, MUKAI TOORU, MIYAKE HIROYA, MIYASHITA KAZUSHI, TAKI KENJI

  日本水産学会北海道支部大会講演要旨集  1997/12
• On the circadian fluctuation of Alaska pollack fish distribution in the Shakotan open sea observed by the quantitative fish finder.  [Not invited]

  ABE KOKI, IIDA KOJI, MUKAI TOORU, MIYAKE HIROYA, KANEDA YUKI, MIZUNO MASAMI, ISHIDA RYOTARO, MUTO TAKASHI

  日本水産学会北海道支部大会講演要旨集  1997/12
• Daytime/nighttime fluctuation of echogram of Alaska pollack fish school in Musashi pile obtained by measure fish finder.  [Not invited]

  ABE KOKI, IIDA KOJI, MUKAI TOORU, KANEDA YUKI, MIYAKE HIROYA, MIZUNO MASAMI

  日本水産学会大会講演要旨集  1997/04
• Frequency characteristics of acoustic scattering layer in the Sea of Japan in west Hokkaido using measure fish finder.  [Not invited]

  MORI HIDEKI, IIDA KOJI, MUKAI TOORU, YOSHIDA HIDEO, MIYAKE HIROYA

  日本水産学会大会講演要旨集  1997/04
• Measurement of target strength of Alaska pollack and Pacific cod fish larvae by cage method.  [Not invited]

  IIDA KOJI, MUKAI TOORU, O TOSHIN, NATSUME MASASHI

  日本水産学会大会講演要旨集  1997/04
• Estimation of Alaska pollack resources in the northern Sea of Japan using measure fish finder.  [Not invited]

  KANEDA YUKI, IIDA KOJI, MUKAI TOORU, MIYAKE HIROYA, MIZUNO MASAMI, YOSHIDA HIDEO, ISHIDA RYOTARO, NATSUME MASASHI

  日本水産学会大会講演要旨集  1997/04
• Target Strength of Encaged Juvenile Fish  [Not invited]

  Proceedings of International Workshop on Acoustic Surveys of North Pacific Fisheries Resources, Pusan, Korea, 1-11  1997
• On the frequency characteristics of Alaska pollack and Zooplankton in Hokkaido-western Japan sea measured by the quantitative fish finder.  [Not invited]

  MORI HIDEKI, IIDA KOJI, MUKAI TOORU, YOSHIDA HIDEO, KANEDA TOMONORI

  日本水産学会北海道支部大会講演要旨集  1996/12
• Measurement of target strength of the fingerlings of Alaska pollack and Pacific cod by the cage method.  [Not invited]

  IIDA KOJI, MUKAI TOORU, O TOSHIN, NATSUME MASASHI

  日本水産学会北海道支部大会講演要旨集  1996/12
• Distribution of Alaska pollack in the Hokkaido-western Japan sea observed by quantitative fish finder EK500 and BI500 system.  [Not invited]

  KANEDA TOMONORI, IIDA KOJI, MUKAI TOORU, MIYAKE HIROYA, MIZUNO MASAMI, YOSHIDA HIDEO, ISHIDA RYOTARO, ABE KOKI, NATSUME MASASHI

  日本水産学会北海道支部大会講演要旨集  1996/12
• On the target strength of adult fish of arabesque greenling ( non-labelled fish ) and Alaska pollack ( labelled fish ).  [Not invited]

  MUKAI TOORU, IIDA KOJI, KANEDA TOMONORI, MIYAKE HIROYA, MIZUNO MASAMI

  日本水産学会北海道支部大会講演要旨集  1996/12
• On the daytime and nighttime fluctuation of target strength of Alaska pollack around Musashi-tai.  [Not invited]

  ABE KOKI, IIDA KOJI, MUKAI TOORU, KANEDA TOMONORI, MIZUNO MASAMI, MIYAKE HIROYA

  日本水産学会北海道支部大会講演要旨集  1996/12
• On the characteristics of the echogram and oceanic environment of the Alaska pollack egg-depositing group coming to Funka bay.  [Not invited]

  KAMIYA EIJI, IIDA KOJI, MUKAI TOORU

  日本水産学会北海道支部大会講演要旨集  1996/12
• Measurement of target strength of one-year Alaska pollack by measure fish finder (EK500).  [Not invited]

  MIYAKE HIROYA, MUKAI TOORU, MIZUNO MASAMI, KANEDA TOMONORI, IIDA KOJI

  日本水産学会北海道支部大会講演要旨集  1995/12
• Error of resources estimated by sea bottom dead zone in sound resource survey of ground fishes.  [Not invited]

  KO TOSHIN, IIDA KOJI, MUKAI TOORU

  日本水産学会北海道支部大会講演要旨集  1995/12
• Handling of target strength of fish larva in sound resource survey.  [Not invited]

  IIDA KOJI, MUKAI TOORU, KO TOSHIN

  日本水産学会北海道支部大会講演要旨集  1995/12
• Horizontal and vertical distribution of summertime Alaska pollack fish school in sea areas around Musashi Pile observed by measure fish finder (EK500).  [Not invited]

  KANEDA TOMONORI, MUKAI TOORU, MIZUNO MASAMI, MIYAKE HIROYA, IIDA KOJI

  日本水産学会北海道支部大会講演要旨集  1995/12
• Target strength of Alaska pollack in sea areas around Musashi Pile obtained by measure fish finder (EK500).  [Not invited]

  MUKAI TOORU, IIDA KOJI, MIZUNO MASAMI, KANEDA TOMONORI, MIYAKE HIROYA

  日本水産学会北海道支部大会講演要旨集  1995/12
• Sound research method of aquatic resources.Present states and prospects.Acoustic scattering characters of fishes.Effect of attitudes.  [Not invited]

  MUKAI TOORU

  月刊海洋  1994/10

Works

• 海洋計測学 Marine Metrology（学部専門）の授業紹介コース

  Tohru MUKAI LASBOS Moodle 2021/02 - Today
• 海洋音響学 Ocean Acoustics（学部専門）の授業紹介コース

  向井 徹 LASBOS Moodle 2021/02 - Today
• Underwaterc Observation using Sound Waves ～Looking into the Sea with Sound～

  Mukai Tohru, Hasegawa Kohei LASBOS Moodle 2020/06 - Today
• Underwater Positioning

  Kohei HASEGAWA, Tohru MUKAI LASBOS Moodle 2020/06 - Today

MISC

• スケトウダラ稚魚のターゲットストレングスの体長依存性および周波数特性

  閻乃箏, 向井徹, 長谷川浩平, 山本潤  日本水産学会大会講演要旨集(CD-ROM)  2023-  2023
• 懸垂法を用いたマサバの広帯域ターゲットストレングス特性

  王梓, 閻乃箏, 長谷川浩平, 向井徹  日本水産学会大会講演要旨集(CD-ROM)  2023-  2023
• 北海道噴火湾周辺海域に生息するカイアシ類,オキアミ類,タンキャク類とスケトウダラ稚魚の周波数特性

  段ぎょく, 長谷川浩平, 閻乃箏, 向井徹  日本水産学会大会講演要旨集(CD-ROM)  2023-  2023
• 多周波数音響プロファイラーを用いた噴火湾砂原沖の魚群観測

  長谷川浩平, 向井徹, 閻乃箏, 東一彦  日本水産学会大会講演要旨集(CD-ROM)  2023-  2023
• 計量魚群探知機による琵琶湖固有種アナンデールヨコエビの分布調査

  藤田航生, 石川可奈子, 永田貴丸, 閻乃箏, 長谷川浩平, 向井徹  日本水産学会大会講演要旨集(CD-ROM)  2023-  2023
• Bottom classification from backscattering data collected by quantitative echosounders in Funka Bay, Hokkaido

  大谷寛礼, 向井徹, 長谷川浩平, YAN Naizheng  海洋音響学会研究発表会講演論文集  2023-  2023
• Broadband target strength characteristics of juvenile walleye pollock

  YAN Naizheng, 向井徹, 長谷川浩平, 山本潤  海洋音響学会研究発表会講演論文集  2023-  2023
• 我が国沖合海域における海洋プラスチックごみ調査の規準化およびデータベース整備

  内田圭一, 萩田隆一, 向井徹, 今井圭理, 清水健一, 八木光晴, 山中有一, 三橋廷央, 磯辺篤彦, 黒田真央  日本水産学会大会講演要旨集(CD-ROM)  2023-  2023
• 北海道大学地域水産業共創センターと産学官連携事業の紹介

  福田覚, 三瓶真, 阿部義之, 今村聖祐, 佐藤哲生, 浦和寛, 大木淳之, 向井徹, 藤森康澄, 細川雅史, 綿貫豊, 都木靖彰  産学連携学会大会講演予稿集(CD-ROM)  21st-  2023
• 生物多様性保全・再生に関する研究

  石川可奈子, 酒井陽一郎, 法理樹里, 法理樹里, 東善広, 井上栄壮, 永田貴丸, 向井徹  滋賀県琵琶湖環境科学研究センター研究報告書(Web)  (19)  2023
• Current status of fish species discrimination by broadband quantitative echosounder

  Mukai Tohru  THE JOURNAL OF THE ACOUSTICAL SOCIETY OF JAPAN  78-  (6)  322  -327  2022
• Exploring the Possibility of a “Copepod Fishery” targeting on the Marine Lower Trophic Organisms

  山口篤, 松石隆, 向井徹, 藤森康澄, 別府史章, 細川雅史  日本ベントス学会・日本プランクトン学会合同大会講演要旨集  2021-  2021
• 低次栄養段階生物を対象とした「かいあし漁業」の可能性を探る

  山口篤, 松石隆, 向井徹, 藤森康澄, 別府史章, 細川雅史  日仏海洋学会学術研究発表会講演要旨集  2021 (CD-ROM)-  2021
• 低次栄養段階生物を対象とした「かいあし漁業」の可能性を探る

  山口篤, 松石隆, 向井徹, 藤森康澄, 別府史章, 細川雅史  日本水産学会北海道支部大会講演要旨集  2020 (CD-ROM)-  2020
• 三陸サケ回帰率向上のための放流技術の開発 餌環境把握技術の開発

  澤田浩一, 松裏知彦, 向井徹, 福田美亮, 長谷川浩平, 安部幸樹, 佐々木系, 山田雄一郎  月刊海洋  50-  (11)  511‐518  2018/11/01  [Not refereed][Not invited]
  
• Development of release methods for chum salmon in Sanriku coast

  Horii Toyomitsu, Kurokawa Tadahide, Mukai Tohru, Yamada Yuichiro, Nikaido Hideki, Yatsuya Miwa, Sawada Kouichi  NIPPON SUISAN GAKKAISHI  84-  (5)  944  -950  2018/09  [Not refereed][Not invited]
  
• Study on acoustic scattering characteristics of pointhead flounder Cleisthenes pinetorum : Characteristics of pointhead flounder observed with a quantitative echosounder

  向井 徹, 閻 乃筝, 山本 潤, 長谷川 浩平  電子情報通信学会技術研究報告 = IEICE technical report : 信学技報  118-  (199)  29  -32  2018/08/30  [Not refereed][Not invited]
  
• Study on acoustic scattering characteristics of pointhead flounder Cleisthenes pinetorum : Target strength measurements of pointhead flounder using a broadband acoustic system

  閻 乃筝, 向井 徹, 山本 潤, 工藤 尚之, 長谷川 浩平  電子情報通信学会技術研究報告 = IEICE technical report : 信学技報  118-  (199)  33  -36  2018/08/30  [Not refereed][Not invited]
  
• Study on acoustic scattering characteristics of pointhead flounder Cleisthenes pinetorum―Characteristics of pointhead flounder observed with a quantitative echosounder―

  向井徹, YAN Naizheng, 山本潤, 長谷川浩平  電子情報通信学会技術研究報告  118-  (199(US2018 41-48))  29‐32  2018/08/23  [Not refereed][Not invited]
  
• Study on acoustic scattering characteristics of pointhead flounder Cleisthenes pinetorum―Target strength measurements of pointhead flounder using a broadband acoustic system―

  YAN Naizheng, 向井徹, 山本潤, 工藤尚之, 長谷川浩平  電子情報通信学会技術研究報告  118-  (199(US2018 41-48))  33‐36  2018/08/23  [Not refereed][Not invited]
  
• 音響手法によるフレーム型中層トロール(FMT)の採集効率の推定-周波数特性の影響-

  LU Zhen, 向井徹, 藤森康澄, 飯田浩二  海洋音響学会研究発表会講演論文集  2018-  2018
• Foreword

  HORII TOYOMITSU, KUROKAWA TADAHIDE, MUKAI TOHRU, YAMADA YUICHIRO, NIKAIDO HIDEKI, YATSUYA MIWA, SAWADA KOUICHI  NIPPON SUISAN GAKKAISHI  84-  (5)  944  -944  2018  [Not refereed][Not invited]
  
• Development of an online multi-frequency profiler for monitoring zooplankton

  Kouichi Sawada, Tomohiko Matsuura, Kohei Hasegawa, Tohru Mukai, Matt Stone, Kei Sasaki, Hideki Nikaido  2018 OCEANS - MTS/IEEE KOBE TECHNO-OCEANS (OTO)  2018  [Not refereed][Not invited]
   

  The density of zooplankton within bays and in inshore areas is an important environmental parameter for determining the optimal release timing of juvenile salmon (Oncorhynchus keta) from hatchery stations. This is because the juveniles remain in these areas for 1 month, during which time they feed upon zooplankton before they begin their journey to the ocean. We monitored zooplankton, water temperature and salinity from 2013 to 2017 in Yamada Bay, Iwate Prefecture, Japan, using a multi-frequency acoustic profiler collocated with temperature-salinity sensors and a depth sensor. Our observations revealed that the large zooplankton preferred by juvenile salmon are transported into the bay by the Oyashio Current. Therefore, it is important to determine the timing of this transportation. We developed an online profiler to record these events at a hatchery station in Yamada Bay.
• Acoustic distinction between pointhead flounder and juvenile walleye pollock by echo shape and frequency characteristics

  Naizheng Yan, Tohru Mukai, Jun Yamamoto  2018 OCEANS - MTS/IEEE KOBE TECHNO-OCEANS (OTO)  2018  [Not refereed][Not invited]
   

  This study addresses the methods for distinguishing the pointhead flounder Cleisthenes pinetorum from the juvenile walleye pollock Gadus chalcogrammus in and near Funka Bay, Hokkaido, Japan. Acoustics data of th Gadus chalcogrammus e fish were monitored using a Simrad EK60 (38, 120, 200 kHz) split-beam echo sounder, and biological samples were collected using a rod for the pointhead flounder and a frame-type midwater trawl for the juvenile walleye pollock. The pointhead flounder schools presented a patch shaped echo on the echograms and showed strong scattering at all three frequencies, whereas the distribution patterns of the juvenile walleye pollock schools were layered. The volume backscattering strength (SV) of the target schools extracted from the echograms showed that the pointhead flounder presented a higher SV at high frequency, which is consistent with the early surveys of other bladderless fish. In contrast, the juvenile walleye pollock showed higher SV at low frequency, which also agreed with the early surveys.
• 3. Development of monitoring technique for estimating zooplankton density by size using multi-frequency profiler

  SAWADA KOUICHI, MATSUURA TOMOHIKO, MUKAI TOHRU, FUKUDA YOSHIAKI, HASEGAWA KOHEI, ABE KOKI, SASAKI KEI, YAMADA YUICHIRO  NIPPON SUISAN GAKKAISHI  84-  (5)  947  -947  2018  [Not refereed][Not invited]
  
• Translated Paper : Measurement of Fish School Backscattering Strength Directivity Using Omnidirectional Scanning Sonar

  TAKAHASHI Ryuzo, IIDA Koji, MUKAI Tohru, NISHIMORI Yasushi  海洋音響学会誌 = The journal of the Marine Acoustics Society of Japan  43-  (3)  145  -160  2016/07
• Measurement of Fish School Backscattering Strength Directivity Using the Omnidirectional Scanning Sonar

  高橋 竜三, 飯田 浩二, 向井 徹  海洋音響学会誌 = The journal of the Marine Acoustics Society of Japan  43-  (1)  26  -30  2016/01  [Not refereed][Not invited]
  
• 大型クラゲNemopilema nomuraiの音響調査手法

  広瀬美由紀, 向井徹  日本水産学会大会講演要旨集  2014-  2  2014/03  [Not refereed][Not invited]
  
• クラゲの形状変化に伴う音響散乱特性

  広瀬美由紀, 向井徹, 福田美亮, 澤田浩一  海洋音響学会研究発表会講演論文集  2012-  7  -10  2012/05  [Not refereed][Not invited]
  
• Acoustic Characteristics of Nemopilema nomurai

  広瀬 美由紀, 黄 斗湊, 向井 徹  海洋音響学会誌  39-  (1)  34  -38  2012/01  [Not refereed][Not invited]
  
• 遊泳姿勢に伴うミズクラゲの音響散乱特性

  広瀬美由紀, 向井徹, 福田美亮, 澤田浩一  海洋音響学会研究発表会講演論文集  2011-  81  -84  2011/05  [Not refereed][Not invited]
  
• Development of broadband transducer using multilayer piezoelectric elements

  K. Amakasu, Y. Mishima, K. Sawada, T. Mukai, T. Sasakura  2011 IEEE Symposium on Underwater Technology, UT'11 and Workshop on Scientific Use of Submarine Cables and Related Technologies, SSC'11  2011  [Not refereed][Not invited]
   

  A Langevin-type broadband transducer was developed using a multilayer piezoelectric actuator (hereafter referred to as a multilayer piezoelectric element). The frequency range of the broadband transducer was aimed to cover the frequency range from 38 to 120 kHz typically used for sensing fish and zooplankton. The 10-mm long multilayer piezoelectric elements whose resonance frequency is 138 kHz were chosen for covering the high-frequency region. Acrylic disks of 13-mm thick as the front and rear masses were used for realizing the resonance at the low-frequency region. Also the diameter of 11 cm was determined for realizing suitable beamwidths 5-20°. Thirty elements were set in circular-shaped arrays on the disk and the two acrylic disks were fastened with four bolts. The peaks of the transmitting sensitivity were measured at 46 and 135 kHz, and the values were 168.3 and 165.3 dB re 1 μPa/V, respectively. Although ripples were observed, useful band around 46 and 135 kHz were 2665 kHz (39-kHz bandwidth) and 110142 kHz (32-kHz bandwidth), respectively. The transmitting sensitivity function from 70 to 105 kHz was flat, but the sensitivity of 158.0 dB re 1 μPa/V was lower than those of the above frequency range. The peaks of the receiving sensitivity were measured at 28 and 135 kHz, and the values were 188.5 and 173.6 dB re 1 μPa/V, respectively. The receiving sensitivity function was not flatter than the transmitting sensitivity function and the sensitivity at 70 kHz of 207.9 dB re 1 V/μPa was considerably low. The measured beam patterns at 38, 70, and 120 kHz were almost the same as that of the 11-cm diameter circular piston source. The broadband acoustic system was constructed using commercially available equipments and the measurement of the target strength spectra of a 38.1-mm diameter tungsten carbide sphere using a 20150 kHz linear-frequency-modulated signal. The measured target strength spectra of the 38.1-mm sphere were in good agreement with the predictions except for the region of the low signal-to-noise ratio. © 2011 IEEE.
• Effect of artificial light on sampling with plankton net for euphausiid

  Yasuzumi Fujimori, Tohru Mukai, Jun Yamamoto  NIPPON SUISAN GAKKAISHI  76-  (6)  1080  -1082  2010/11  [Not refereed][Not invited]
  
• 姿勢変化に伴うエチゼンクラゲ(Nemopilema nomurai)の音響散乱特性

  広瀬美由紀, 向井徹, HWANG Doo‐Jin  海洋音響学会研究発表会講演論文集  2010-  65  -68  2010/05  [Not refereed][Not invited]
  
• Characteristics of Acoustic Scattering according to Pulsation of the Large Jellyfish Nemopilema nomurai

  Kor. J. Fish. Aquat. Sci  43-  (5)  551  -556  2010  [Not refereed][Not invited]
  
• ミズクラゲのターゲットストレングス―拍動および姿勢による変化―

  向井徹, 広瀬美由紀, 澤田浩一, 高橋春香, 飯田浩二  海洋音響学会研究発表会講演論文集  2009-  19  -22  2009/05  [Not refereed][Not invited]
  
• 拍動および超音波入射角の変化によるミズクラゲのターゲットストレングスの変化

  向井徹, 広瀬美由紀, 澤田浩一, 石井憲, 高橋春香, 飯田浩二  日本水産学会大会講演要旨集  2009-  6  2009/03  [Not refereed][Not invited]
  
• オキアミ類,カイアシ類,タンキャク類に対するLOPCの計測特性

  山下由起子, 藤森康澄, 向井徹, 木村暢夫  日本水産学会大会講演要旨集  2009-  2009
• 2E6-1 Optimal Fish Target Strength for Detecting Fish School using Horizontal Echosounder(Oral Session in English III)

  Kurnia Muhammad, Iida Kohji, Mukai Tohru  Proceedings of Symposium on Ultrasonic Electronics  30-  (0)  389  -390  2009  [Not refereed][Not invited]
  
• The variation of density and sound speed contrasts and theoretical target strength estimation of Euphausia pacifica

  Ryuichi Matsukura, Tohru Mukai, Yasuhiro Ando, Kohji Iida  NIPPON SUISAN GAKKAISHI  75-  (1)  38  -44  2009/01  [Not refereed][Not invited]
   

  The density and sound speed contrasts between Euphausia pacifica and sea water change with the season. In this study, we examined the effect on target strength (TS) and lipid content which is a cause of these changes. Density contrasts increased from spring to summer, but sound speed contrasts decreased. There was a negative correlation between density contrasts and wax esters, which are one of the lipid contents, and a positive correlation between sound speed contrasts and total lipid. The range of variation estimated by the DWBA model using both ratios was narrow. The mean TS of E. pacifica (TL 15 mm) ranged from -105.9 to -105.2 dB at 38 kHz, from -91.3 to -90.5 dB at 120 kHz and from -86.3 to -85.4 dB at 200 kHz.
• クラゲ類の体内音速および生体密度―エチゼンクラゲ,ミズクラゲ,ユウレイクラゲ―

  広瀬美由紀, 向井徹, 飯田浩二, 飯泉仁  海洋音響学会研究発表会講演論文集  2008-  41  -44  2008/05  [Not refereed][Not invited]
  
• ミズクラゲの生体内音速および生体密度

  広瀬美由紀, 向井徹, 飯泉仁  日本水産学会大会講演要旨集  2008-  26  2008/03  [Not refereed][Not invited]
  
• 音を使って海の中を覗く (特集 音波の海を泳ぐ--見えない波で見る)

  向井 徹  アクアネット  10-  (4)  24  -28  2007/04  [Not refereed][Not invited]
  
• 大型クラゲの音響散乱特性に関する研究

  広瀬美由紀, 向井徹, 飯田浩二  日本水産学会大会講演要旨集  2007-  13  2007/03  [Not refereed][Not invited]
  
• 3-11P-57 Interactive Analysis in Target Strength (TS) Pattern Measurements of Small Aquatic Organism(Poster session 3)

  Ishii Ken, Abe Koki, Sawada Kouichi, Amakasu Kazuo, Mukai Tohru  Proceedings of Symposium on Ultrasonic Electronics  28-  (0)  471  -472  2007  [Not refereed][Not invited]
  
• (Highlights in Fisheries Science Research)

  向井 徹, 北大院水  Bulletin of the Japanese Society of Scientific Fisheries  72-  (4)  757  -757  2006/07/15  [Not refereed][Not invited]
  
• 制御法および音響散乱モデルによるカタクチイワシのターゲットストレングス推定

  谷上 俊介, 福田 美亮, 向井 徹, 飯田 浩二  日本水産工学会学術講演会講演論文集  18-  295  -298  2006/06/10  [Not refereed][Not invited]
  
• 噴火湾におけるスケトウダラ分布のGIS解析

  石原 俊輔, 向井 徹, 飯田 浩二  日本水産工学会学術講演会講演論文集  18-  299  -302  2006/06/10  [Not refereed][Not invited]
  
• 医療用超音波カメラによる魚体内部の音響画像の特徴

  高橋 里佳, 飯田 浩二, 湯 勇, 向井 徹, 佐藤 正典  日本水産工学会学術講演会講演論文集  18-  305  -308  2006/06/10  [Not refereed][Not invited]
  
• 計量魚群探知機を用いた東シナ海における大型クラゲNemopilema nomuraiの音響調査

  広瀬美由紀, 向井徹, 飯田浩二, 黄斗湊  日本水産学会大会講演要旨集  2006-  12  2006/03  [Not refereed][Not invited]
  
• エチゼンクラゲとユウレイレイクラゲの音響散乱特性の比較

  広瀬美由紀, 向井徹, 黄斗湊, 飯田浩二  日本水産学会大会講演要旨集  2005-  20  2005/04  [Not refereed][Not invited]
  
• P1-65 Application of ultrasonography for morphological measurement of marine fish

  Takahashi Rika, Iida Kohji, Tang Yong, Mukai Tohru, Sato Masanori  Proceedings of Symposium on Ultrasonic Electronics  26-  (0)  167  -168  2005  [Not refereed][Not invited]
  
• P2-44 Behavior of Marine Animals Using Underwater Acoustic Camera(Short oral presentation for posters)

  IIDA Kohji, Tang Yong, MUKAI Tohru, Takahashi Rika, SATO Masanori  Proceedings of Symposium on Ultrasonic Electronics  26-  (0)  299  -300  2005  [Not refereed][Not invited]
  
• G-4 Measurement of Fish School Volume Using Omnidirectional Multi-Beam Sonar, -Scanning Mode and Algorithm-(Medical ultrasound, Underwater ultrasound)

  Tang Yong, Iida Kohji, Mukai Tohru, Nishimori Yasushi  Proceedings of Symposium on Ultrasonic Electronics  26-  (0)  315  -316  2005  [Not refereed][Not invited]
  
• Studies on acoustic target strength of fish and zooplankton

  MUKAI TOHRU, TOHRU MUKAI, Graduate School of Fisheries Sciences Hokkaido University  NIPPON SUISAN GAKKAISHI  70-  (5)  667  -670  2004/09/15  [Not refereed][Not invited]
  
• エチゼンクラゲの音響散乱特性について

  広瀬美由紀, 向井徹, 黄斗湊, 飯田浩二  日本水産学会大会講演要旨集  2004-  15  2004/03  [Not refereed][Not invited]
  
• Measurements of swimming angles, density, and sound speed of the krill Euphausia pacifica for target strength estimation

  T Mukai, K Iida, Y Ando, H Mikami, Y Maki, R Matsukura  OCEANS '04 MTS/IEEE TECHNO-OCEAN '04, VOLS 1- 2, CONFERENCE PROCEEDINGS, VOLS. 1-4  1-  383  -388  2004  [Not refereed][Not invited]
   

  In recent years, acoustic technology has been used extensively to estimate krill abundance. Acoustic assessment is required to obtain precise estimates of krill target strength (TS). However, predictions of target strength from theoretical scattering models are often influenced by the swimming angle, density, and sound speed contrasts between krill and seawater. Density and sound speed contrasts are known to show annual cycles. In this study, swimming angles and seasonal variations of the specific density and sound speed contrasts of Euphausia Pacifica are presented. Biological sampling was carried out during twilight, when the sound-scattering layer migrates up to the surface. Sound speed measurements were performed on a vessel 2 hours after net sampling, using a T-shaped velocimeter with two transducers mounted at the ends of a horizontal tube. The swimming angles and specific densities of E. Pacifica were measured at a laboratory within 48 hours of net sampling. The specific densities of the krill were measured using a series of glycerol solutions of variable densities. Moreover, the total lipid content, lipid composition, and fatty acid composition of the krill were analyzed. The swimming angles of the krill varied from 30 to 50 degrees in low illumination condition (0.1 Ix). The density and sound speed contrasts changed with the season. These variations depended on the lipid content in the krill body. In particular, the density of the krill changed with the wax ester content. The variations of TS estimated by the distorted-wave Born approximation (DWBA) method will be discussed.
• Acoustic target strength of Japanese common squid, Todarodes pacificus, and important parameters influencing its TS: Swimming angle and material properties

  D Kang, K Iida, T Mukai, D Hwang  OCEANS '04 MTS/IEEE TECHNO-OCEAN '04, VOLS 1- 2, CONFERENCE PROCEEDINGS, VOLS. 1-4  1-  364  -369  2004  [Not refereed][Not invited]
   

  The squids, one of the cephalopods, is important species in fisheries and ecology. If acoustic properties of squid can be well examined, especially target strength (TS), acoustic method can be provided a good tool for squid survey. The purpose of the study is to investigate the TS property of the Japanese common squid, Todarodes pacificus, and parameters influencing TS: swimming angle and material properties, density (g) and sound speed contrast (h). In the swimming angle measurement, the mostly head part of the squid stands below the horizontal axis, and averaged swimming angle was -17.7 degrees (s.d.: +/- 12.7 degrees). Based on the tethered TS measurements, the mean standardized TS values (b(20)) were found to be highly correlated with the tilt angle, and the resultant fitted equations for b20 were expressed as: b(20) = -73.3 + 0.48.theta + 0.0122.theta(2) + 0.00016.theta(3) for 38 kHz and b(20) = -72.6 + 0.53.theta + 0.0134.theta(2) + 0.00014.theta(3) for 120 kHz, where theta is the negative tilt angle in degrees. The material properties, g ranged between 1.0209 and 1.0396 (mean 1.0288), and mean h for individual, multiple and tilted squid were 1.041, 1.042, and 1.039, respectively. In the model estimation, the estimated TS data from the measured h (1.04) were higher than those of previous studied h (1.007) and were close to maximum TS data that were obtained from live squid. The results suggest that further work is needed to conduct the TS measurement for various sized squid, and to decide suitable acoustical parameter for model estimation. These data can help in making acoustics a quantitative survey tool for biomass estimation of the squids.
• Morphological observation of marine organisms by underwater ultrasonography

  K Iida, T Mukai, DY Kang, M Sato  OCEANS '04 MTS/IEEE TECHNO-OCEAN '04, VOLS 1- 2, CONFERENCE PROCEEDINGS, VOLS. 1-4  1-  357  -363  2004  [Not refereed][Not invited]
   

  A high resolution underwater ultrasonic camera enclosed in a pressure-resistant case was developed to observe underwater animals. It enables to measure size, shape, and movement of living marine animals as well as tissue, shape, and movement of internal organs. Ultrasonic camera is originally used for medical diagnosis. A convex/linear type transducer array is driven by 3.5 to 5 MHz ultrasonic signals and the echo from an object is displayed as an acoustic tomogram. It covers a range from 24 to 100cm in waters. The acoustical B mode image and an optical image by an underwater camera were transferred by underwater cable. Special features of the underwater ultrasonic camera are, 1) To observe marine animals in dark or opaque water, 2) To observe the tissue and shape of internal organ, 3) To observe the shape and movement of marine animals in natural conditions. A trial of an underwater ultrasonic camera was conducted in a water tank. Live animals such as fish, squid, jellyfish, and krill were observed by the ultrasonic camera. Also, a three dimensional image of internal structure of animals was constructed by using a series of acoustical tontograms in order to measure size and volume of internal organs. However several acoustical discontinuities in a body were found. The most important contributor for acoustic scattering was a vertebra in non-bladdered fish and a swimbladder in bladdered fish. As for invertebrate animals the major contributors for acoustic scattering were a liver in squid, an ovary in jelly fish, and a shell in crustacean respectively. Finally a real use of ultrasonic camera in coastal waters was conducted. The underwater ultrasonic camera and optical camera were set on a sea bottom at a depth of 12m. Several interesting optical and acoustical images from wild animals were observed.
• Measurement of fish school volume by multi-beam sonar - Directional resolution and estimation error

  K Iida, Y Tang, T Mukai, Y Nishimori  OCEANS '04 MTS/IEEE TECHNO-OCEAN '04, VOLS 1- 2, CONFERENCE PROCEEDINGS, VOLS. 1-4  1-  401  -408  2004  [Not refereed][Not invited]
   

  Multi-beam sonar is very useful for estimating fish abundance because of its wide detection area. In this study, we propose a method for measuring acoustical volume for different modes of a multi-beam sonar. We also tried to measure the shape and volume of a model fish school in a tank using an ultrasound scanner and then measured the shape and volume of an actual fish school in the field using semicircular scanning sonar. However, the measured shape was distorted, and an error was contained in the estimated volume of the fish school. Therefore, we used a computer simulation to consider the error in the measurement volume using a spherical scattering object under various beam widths and distances. The characteristics of the error are presented and the possibility of reducing the error was confirmed.
• Estimation of the variation in target-strength of fish under pressure condition

  K Sawada, T Mukai, K Sadayasu  OCEANS '04 MTS/IEEE TECHNO-OCEAN '04, VOLS 1- 2, CONFERENCE PROCEEDINGS, VOLS. 1-4  1-  389  -394  2004  [Not refereed][Not invited]
   

  This paper reports a newly developed measurement system of fish swimbladder shape under pressure condition and theoretical modeling of bluegill (Lepomis macrochirus) under pressure condition. A pressure tank with a pressure device is used in combination with the existing soft X-ray machine. Observed swimbladder images taken from the lateral aspect are digitized to obtain the fish morphological parameters. Based on these parameters, target strength is calculated using deformed cylinder scattering model. Swimbladder images indicate that the swimbladder is compressed from the ventral side to the backbone of the fish. This fact supports that the swimbladder length is less sensitive to the pressure and the swimbladder height is sensitive to the pressure. Maximum TS in the calculated TS pattern at 59m depth becomes 5.3dB lower than one at the atmosphere condition at the frequency of 38 kHz. Averaged TS, assuming normal distribution of tilt angle with mean of -5.0 degrees (head down) and standard deviation of 15.0 degrees, becomes 4.8dB lower.
• 懸垂法によるエチゼンクラゲ(Stomolophus nomurai)のターゲットストレングス測定

  広瀬美由紀, 向井徹, 黄斗湊, 飯田浩二  日本水産学会北海道支部大会講演要旨集  2003-  19  2003/11  [Not refereed][Not invited]
  
• ベーリング海におけるクラゲの音響探知の試み

  広瀬美由紀, 飯田浩二, 向井徹  日本水産学会北海道支部大会講演要旨集  2002-  62  2002/11  [Not refereed][Not invited]
  
• A quantification of fish school abundance using scanning sonar

  Yoo-Won Lee, Tohru Mukai, Kohji Iida  Fisheries Science  68-  1895  -1896  2002  [Not refereed][Not invited]
  
• Measurements of living squid target strength using tether method with split beam echo sounder.

  ABE KOKI, NAKATA JUN, IIDA KOJI, MUKAI TOORU  イカ類資源研究会議報告 平成12年度  49  -54  2002  [Not refereed][Not invited]
  
• ベルソーブックス007 : 音で海を見る, 古澤昌彦著, (社)日本水産学会監修, 成山堂書店, (2001年), 四六判, 196頁, 1680円

  向井 徹  日本水産学会誌  68-  (4)  587  -587  2002  [Not refereed][Not invited]
  
• Estimations of squid target strength using a small cage and theoretical scattering models

  MUKAI T  The Proceedings of The JSPS-DGHE International Symposium on Fisheries Science in Tropic Area, Indonesia. 2001  135  -140  2001  [Refereed][Not invited]
  
• TAC制度下における直接法による資源量推定技術高度化試験 (北海道立中央水産試験場S)

  高柳志朗, 石田良太郎, 三宅博哉, 和田昭彦, 武藤卓志, 飯田浩二, 向井徹, 安部幸樹, 中野健一  北海道立中央水産試験場事業報告書  2000-  168  -169  2001/01  [Not refereed][Not invited]
  
• 制御法によるスケトウダラ幼稚魚のターゲットストレングスの測定

  岡崎 亜美, 向井 徹, 飯田 浩二  日本水産工学会学術講演会講演論文集  12-  173  -176  2000/06/08  [Not refereed][Not invited]
  
• スキャニングソーナー映像を用いた魚群量の定量化の試み

  李 遺元, 向井 徹, 飯田 浩二  日本水産工学会学術講演会講演論文集  12-  177  -180  2000/06/08  [Not refereed][Not invited]
  
• 20191001

  MUKAI Toru, IIDA Koji  Proceedings of Annual Meeting of the Japanese Society of Fisheries Engineering  2000-  (0)  177  -180  2000  [Not refereed][Not invited]
  
• 20191001

  OKAZAKI Ami, MUKAI Toru, IIDA Koji  Proceedings of Annual Meeting of the Japanese Society of Fisheries Engineering  2000-  (0)  173  -176  2000  [Not refereed][Not invited]
  
• Visiting resources amount estimation basic research of Alaska pollack egg-laying group using measuring fish finder in the Sea of Japan west of Hokkaido.

  TAKAYANAGI SHIRO, ISHIDA RYOTARO, MIYAKE HIRONARI, MIZUNO MASAMI, KANEDA TOMOKI, MUTO TAKASHI, IIDA KOJI, MUKAI TOORU, MORI HIDEKI  北海道立中央水産試験場事業報告書  1997-  172  -173  1999/03  [Not refereed][Not invited]
  
• Calibration of measuring fish finder equipped to ship’s bottom using calibration ball.

  飯田浩二, 向井徹, 三宅博哉, 三原行雄, 本間隆之, 高柳志朗  日本水産学会大会講演要旨集  1998-  1998
• Calibration of measure fish finder equipped in ship’s bottom using calibration ball.

  飯田浩二, 向井徹, 三宅博哉, 三原行雄, 本間隆之, 高柳志朗  日本水産学会北海道支部大会講演要旨集  1997-  1997
• 魚の音響散乱特性-姿勢の影響-

  向井徹  月刊海洋  26-  624  -629  1994
• 魚体の超音波反射特性におよぼす鰾と姿勢の影響に関する基礎的研究

  向井徹  北海道大学学位論文  1994
• The Present States and Prospects of Acoustical Survey Methods of Fisheries Resources. Contribution of the Fish Tilt Angle to the Backscattering by Fish.

  Mukai Tohru  NIPPON SUISAN GAKKAISHI  60-  (6)  797  -798  1994  [Not refereed][Not invited]
  
• Target strength of demersal fish calculated from echo integration and bottom trawl in the East China Sea

  D. Hwang, N. Sano, K. Iida, T. Mukai, K. Masuda, S. Sasaki  Bulletin - Hokkaido University, Faculty of Fisheries  44-  197  -208  1993/01/01  [Not refereed][Not invited]
   

  Describes the target strength of different demersal species calculated from the relationships between weight density from bottom trawling and acoustic volume backscattering strenth. -from English summary
• ヒメマスのターゲットストレングスにおよぼす鰾の影響について

  向井 徹, 鈴木 恒由, 佐野 典達  北海道大學水産學部研究彙報 = Bulletin of the Faculty of Fisheries, Hokkaido University  39-  (2)  106  -114  1988/05  [Not refereed][Not invited]
  

Industrial Property Rights

• 特開2007-089521:多段開閉式ネット及び採集装置  2007/04/12

  藤森 康澄, 山下 成治, 向井 徹  国立大学法人 北海道大学  200903071666836413

Research Grants & Projects

• Exploring the Possibility of a "Copepod Fishery" targeting on the Marine Lower Trophic Organisms

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Pioneering)

  Date (from‐to) : 2020/07 -2026/03 

  Author : 山口 篤, 松石 隆, 向井 徹, 藤森 康澄, 別府 史章

   

  本年度は北海道大学大学院国際食資源学院漁業管理論の一環として「かいあし漁業ワークショップ」を、2020年11月12日～13日にかけて北大函館キャンパスにて開催した。参加者は留学生を中心とする20名弱で、言語は英語で行った。またかいあし漁業に関連する海産動物プランクトンを対象とした漁業として、ナンキョクオキアミ漁業に関する勉強会も開催した。ナンキョクオキアミは、単一生物としては地球上で最も生物量バイオマスの多い種として知られ、人類の食糧資源として注目され、日本も1970年代から漁業を行っていたが、採算ベースに乗らず、2011/2012年を最後に撤退している。ナンキョクオキアミについては、現在はクリルオイルを対象とした漁業がノルウェーを中心に行われている。ノルウェーのナンキョクオキアミ漁業はサプリメントを主要商品としており、漁獲後船上でサプリメントまでを加工する設備を整えた専用船を持ち、MSC認証を受けた企業がある。オキアミ類を対象とした漁業は、日本でも岩手県三陸沖にて、春先にツノナシオキアミを対象とする「イサダ漁」があり、そこで採集されたオキアミを使って「イサダオイル」の開発もなされている。一方、かいあし漁業を行っている企業は世界で唯一、ノルウェーのトロムセーにあり、その主要商品は「Calanus Oil」である。このCalanusとは、ノルウェー海で優占する年1世代を持つ大型カイアシ類Calanus finmarchicusやCalanus hyperboreusの名称である。北大西洋におけるCalanusに比較し得る、北太平洋の種はNeocalanus属で、Neocalanus属は年1世代の世代時間を持ち、体内に油分を貯める性質を持っている。このNeocalanus属を対象とした漁業の確立実行可能性を探るのが重要であるということが、初年度の調査研究の結論としてあげられる。
• Elucidation of acoustic characteristics of the "floating pointhead flounder" by field and tank experiments and realization of acoustic survey of fisheries resources

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2019/04 -2022/03 

  Author : MUKAI Tohru

   

  The acoustic characteristics of pointhead flounder were investigated by field surveys and tank experiments to realize their acoustic resource survey. We accumulated basic information necessary for acoustic resource surveys and identified the optimum survey season. First, in the field survey, we examined the characteristics of the fish schools of pointhead flounder captured by the quantitative echo sounder, and found that they were patchy in the mid-water layer. Next, tank experiments were conducted to investigate the acoustic characteristics and differences in their behavior during the day and night, as a result, acoustic surveys of pointhead flounder should be conducted during the daytime. Finally, we investigated the differences in the frequency characteristics and the echo shapes by the quantitative echo sounder in field surveys of other fish species and zooplankton overlapping with pointhead flounder, and proposed the method for discriminating these species.
• Development of the design method of 3 in 1 fisheries broadband transducer for acoustic survey

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory)

  Date (from‐to) : 2017/06 -2020/03 

  Author : Sawada Kouichi

   

  By using multiple frequencies, it is possible to distinguish between zooplankton such as euphausiids and fish and to estimate the body length. But until now, it was difficult to introduce them in fishing boats because its cost and space for several transducers to be installed. Previous research has revealed that newly developed broadband transducer can transmit and receive multiple frequencies with a single transducer. However, it takes much time to calculate the layout of many elements (array layout) which satisfies the required performance at each frequency. Therefore, we introduced a genetic algorithm used to obtain optimal values in other fields, developed a method for performing the array layout calculation in a short time, and confirmed it through experiments. To verify the design parameters, we have developed a method to reduce the measurement error in the experiment.
• Development of quantitative monitoring method for zooplankton inhabiting the ocean twilight zone

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

  Date (from‐to) : 2014/04 -2018/03 

  Author : MUKAI TOHRU

   

  This application was aimed at developing a method of quantifying zooplankton inhabiting the ocean twilight zone with depths of 200 to 500 meters using a combination of the acoustic and the optical method. Using the acoustic method, besides krill, which has many examples of measurements up to now, it was also possible to measure the acoustic scattering cross-section which is the scale factor in quantification for copepods and amphipods. On the other hand, with the optical method, it was possible to photograph zooplankton at depths of up to 100 meters using a general-purpose digital camera with external flash. Further shooting at greater depths could not be realized due to troubles in the equipment.
• Development of new zooplankton observation method using linear FM signals and spectral analysis

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

  Date (from‐to) : 2013/04 -2016/03 

  Author : Amakasu Kazuo, MUKAI Tohru, SASAKURA Toyoki

   

  A broadband echosounder which can use high-frequency linear FM signals was built. The usable frequency range is 250 to 700 kHz and is suitable for zooplankton observation. A calibration method using a 38.1-mm diameter tungsten carbide sphere was established for this echosounder. This method uses a specular echo from the sphere, which can obtained by applying the pulse compression processing to the received echo and improving the range resolution. Spectrum measurement for a 20.6-mm sphere and 20 to 40-mm-long shrimps was conducted in a tank and then we confirmed that specific spectra which depend on targets can be obtained. The results of this study are useful for developing a new zooplankton observation method.
• Development of a broadband echosounder using multilayer piezoelectric elements for surveys of marine organisms

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A)

  Date (from‐to) : 2011/04 -2015/03 

  Author : AMAKASU Kazuo, MUKAI Tohru, MOTEKI Masato, SASAKURA Toyoki

   

  A broadband echosounder with a broadband transducer using multilayer piezoelectric actuators (elements) and related analysis methods were developed. The features of this system are that a broadband sound with a frequency band of 20-200 kHz can be transmitted and received, and acoustic scattering spectra of marine organisms such as fish and zooplankton can be determined from their echoes. Since the acoustic scattering spectra include their biological information (e.g., species or taxon, size, and behavior), the biological information can be determined without net sampling. This technology allows surveys of the marine organisms by observation platforms in which net samplings are impossible (e.g., AUV and glider). This technology can be applied to fisheries and to observations for gas bubbles and seafloor.
• Investigation on the acoustic scattering signatures of Copepods-The first step to conducting acoustic survey on copepods-

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

  Date (from‐to) : 2009 -2011 

  Author : MUKAI Tohru, SAWADA Kouichi

   

  Properties of the animal's acoustic scattering(Target Strength : TS) were investigated in copepods which have the highest population among zooplanktons living in the ocean. TS of copepods were measured in a sea-water tank, and estimated using the theoretical model by measuring the acoustic parameters. Both TS were compared. As a result, it was confirmed that TS estimates matched the actual measurements of some individuals well while entirely differed with other individuals. When the differences were investigated, it was found that the former individuals did not have oil sac into the copepods body while the latter individuals had oil sac. We will further investigate this difference in detail.
• 音響技術を用いた水中映像定量化技術の開発

  日本学術振興会：科学研究費助成事業 萌芽研究

  Date (from‐to) : 2005 -2007 

  Author : 向井 徹, 山本 潤

   

  本研究では,水中ロボットカメラ(ROV)によって得られた水中映像に計量魚群探知機による音響映像を組み合わせ,水中映像の定量化技術の開発を開発することを目的としている.さらに,近年,注目されている現象を対象とし,その現象のメカニズム解明のための基礎的なデータを取得することも目指し,本研究では,その被害が問題となった日本海の大型くらげを主な対象として研究した.具体的には,平成18年度に北海道大学水産学部付属練習船おしょろ丸(船底装備の計量魚群探知機を装備)の日本海調査(9月下旬〜10月上旬)に乗船し,北海道奥尻島沿岸から本州・日本海沿岸域で大型くらげの目視調査を行った.ROVによる大型くらげの観察は,目視観察により大型くらげが高密度で分布する海域で実施した。この調査では,船上から,水中遊泳するクラゲの視認が困難である場合も,ROVを用いることにより,その鉛直的な分布特性のデータを取得することができ,さらに,これらの大型クラゲの分布深度では,計量魚群探知機においても,大型クラゲからのエコーを確認することができた。平成19年度では,単なるエコーグラム上での確認ではなく,その分布密度,サイズを検出するために,クラゲの音響的な特性を解析した。その結果,クラゲの音響散乱強度は,体サイズよりも周波数や遊泳姿勢などに強く影響を受けることが明らかになった。今後,ROVによって遊泳姿勢とサイズを測定し,音響データと併せて解析することによリクラゲの浮遊分布の定量化が可能となると考えられる。また本研究で解析した手法を他の魚種,プランクトンなどに応用することによって,水中映像の音響データによる定量化が十分可能であると考えられる。本研究の成果は現在投稿中である。
• 医療超音波カメラを用いた海中生物の微細構造の解明

  日本学術振興会：科学研究費助成事業 萌芽研究

  Date (from‐to) : 2003 -2005 

  Author : 飯田 浩二, 向井 徹, KANG Donhyug, TANG Yong, 佐藤 正典

   

  医療用超音波診断装置を耐圧容器に入れた水中音響ヵメラを用いて海洋生物を至近距離から観察し,生物の形状,姿勢,骨格、体内器官,行動などを定量的に測定する無侵襲の生物計測手法の開発を目的とした。1.水中超音波カメラの改良原型の医療用超音波診断装置は焦点距離が30cmなので,制御ソフトウェアを改造し,最大焦点距離2.4mまでの高解像度の水中音響画像を取得できるようにした。さらに,音響カメラと水中光学カメラを並置させ,光学/音響画像を同時に表示させるようにした。また,、水槽観察においては自動直線走査装置(リニアステージ)を用いて魚体内部の生体構造を糖密観察できるようにした。2.水槽飼育生物の音響画像の解析リニアステージを用いることにより,さらに高解像度の音響画像を得ることができ,魚類の脊椎骨,浮袋,肝臓,生殖腺等の形状を非破壊測定し,解剖結果と比較して,10%以下の誤差で測定できた。特に生殖腺の音響画像に着目し,外形からは判別が不可能なマダラの雌雄の判別を可能にした。さらにマダラ,サケ,スケトウダラ,ハタハタなどの卵巣体積めほか音響画像の解析により卵粒径の大きさを推定した。3.現場海洋生物の音響画像の解析昨年と同様に北海道南茅部町の水深12mの海底に音響カメラを設置し,約1週間生物観察をおこなった。ホッケ,アイナメ,タコ,クラゲ,ヒトデ,カジなど多くの生物が音響画像に記録され,光学カメラ画像から,対象生物を確認することができた。夜間にはヨコエビや動物プランクトンの群れが海藻の内部から間歇的に出入りする様子が確認された。また,出現生物の体長や遊泳速度を推定することができた。
• VISUALIZATION AND QUANTIFICATION OF MARINE BIOLOGICAL RESOURCES USING BI-PLANE SCANNING SONAR

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

  Date (from‐to) : 2003 -2005 

  Author : IIDA Kohji, YOSHIMURA Yasuo, MUKAI Tohru, MIYASHITA Kazushi

   

  The scanning sonar can detect fish school much wider area in the water compared to an echo sounder. The purpose of this study is to develop the new generation quantitative scanning sonar to measure the shape, the volume and the density of the fish school for fisheries survey.1)The quantitative sonar we developed was installed on the fishing boat in Norway and we measured the fish school volume with purse seine fishing for herring and blue whiting. The new sonar was also tested in domestic fishing ground with purse seine fishing for mackerel, squid and yellow tail. Fish schools were detected more than 3,000 meters far from the boat, and the good linear relationship between estimated volume and the catch were found.2)To estimate density of fish school by echo integration method, the target strength in side aspect is necessary. We measured the 3-dimensional target strength of anchovy in sonar frequencies. The target strength in side aspect agreed well to the TS in dorsal aspect, and it showed the "8" figured directional pattern.3)To calculate fish number from the fish school volume, the specific occupation volume by a single fish (Tv) is required. We estimated Tv of walleye pollock dividing the volume backscattering strength (Sv) of fish school by the target strength of fish. Results showed that the Tv is proportional to the 2.6th power of the body length.4)Using the successive multiple sonar images of fish school obtained by the vertical mode, the three dimensional shape of fish school was reconstructed by 3D image processing techniques.5)Results of the study were presented at fisheries and acoustics symposiums. Some of them were applied for domestic and international patents.
• Development of WYSIWYG-Net for simultaneous sampling of plankton and micro-nekton

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2002 -2004 

  Author : FUJIMORI Yasuzumi, MUKAI Tohru, YAMASHITA Nariharu

   

  This study is consist of two kinds of categories as shown below.1.Development of automated opening/closing system for WYSIWYG-Net: Automated opening/closing system to achieve the multi-layer sampling for plankton and micro-nekton was developed. This system could be worked without an armored cable winch system and allows to conduct multi-layer sampling on any research vessel.2.Utilization of LOPC (Laser Optical Plankton Counter) with net : The platform unit was made for zooplankton sampling with LOPC and the data from the net and LOPC were compared. From these results, the methods to estimate the density and to make a species distinction for zooplankton (krill, copepoda, etc.) were developed.
• Fundamental study on multi-dimensional sensing of marine living resources and their environment

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

  Date (from‐to) : 2001 -2003 

  Author : SAITOH Sei-ichi, IIDA Koji, MIURA Teisuke, MUKAI Toru, YONETA Kunisaburo, FUJIMORI Yasuzumi

   

  It is very important that we develop multi-dimensional sensing in combined with satellite remote sensing, underwater remote sensing and direct survey to predict when, where and how much are marine living resources available. Objectives of this study are to develop methodology of multi-dimensional sensing of marine living resources and their environment and to monitor three-dimensional distributions of Japanese common squid and three dimensional environment using acoustic with towed body transducer and real-time towing CTD system with satellite images. Major results are as follows :(1)Observation depth of real-time towing CTD system is from 10 meter to 80 meter in the condition of the length of wire of 300 meter and ship running speed of 10 knot.(2)Three-dimensional observation in the southeastern Bering Sea was successful to gather environmental structure and biomass of fishes using real-time towing CTD and acoustic system EK500. Visualization those three-dimensional distribution was established using AVS software.(3)In the First Oyashio intrusion region off Cape Erimo, three-dimensional fine structure was observed using real-time towing CTD system and acoustic system.
• 動物プランクトンの生体密度と生体内音速の変化に伴う音響反射率の変動の測定

  日本学術振興会：科学研究費助成事業 奨励研究(A)

  Date (from‐to) : 2000 -2001 

  Author : 向井 徹

   

  1.プランクトンの生体密度および生体内音速の測定:今年度の動物プランクトンの採集は,4月から11月にかけて北海道噴火湾において行ない,この海域の優占種であるツノナシオキアミの生体密度および生体内音速の測定を行なった。測定法は例年行なっているdensity bottle法およびTime of flight法によった。その結果,噴火湾のツノナシオキアミの生体密度は体長にあまり依存せず,ほぼ一定の値になることが示唆された。2.プランクトンの音響反射率の測定:動物プランクトンの音響反射率の実測を,周波数170kHzと230kHzの2周波数を備えた低ノイズ型TS測定装置で行なった。前年度に明らかになった送受波器の指向性の影響は,送受信系の改造により,かなり低減されていた。活きたツノナシオキアミに麻酔をかけて,この装置を用いて音響反射を実測した。また,これと同時に,水中カメラを水槽内に設置し,ツノナシオキアミの姿勢を観察した。その結果,姿勢のちょっとした変化によりツノナシオキアミの音響反射率が大幅に変化し,本装置によってもノイズにマスクされ音響反射率が測定できない部分も見られた。しかし,これらの実測値と上記1のパラメータを用いて音響理論モデルから推定された音響反射率の間には,非常に良い一致を見る事が出来た。従って,ノイズにマスクされた部分も,モデルにより推定できると考える。また,本方法により,生体密度・生体内音速の季節変化に伴う音響反射率の変化を実測で把握することが出来,これをモデルで推定することも出来た。今後は,ツノナシオキアミ以外の動物プランクトンへの本方法の適用,低ノイズ型TS測定装置の更なる改良,および現場における音響反射率の測定を試み,動物プランクトンの音響調査手法の確立を目指してく。
• 動物プランクトンの音響反射率の推定に必要な生体密度と生体内音速の測定

  日本学術振興会：科学研究費助成事業 奨励研究(A)

  Date (from‐to) : 1998 -1999 

  Author : 向井 徹

   

  本年度は、実際に5月から9月にかけて、北海道噴火湾で捕獲した生きたツノナシオキアミの生体密度および生体内音速の測定を行った。測定法は前年度に確立した方法であり、生体密度の測定には海水とグリセロールの混合溶液を用いたdensity bottle法を用い、生体内音速の測定はTチューブを用いたTime of flight法によった。その結果、噴火湾のツノナシオキアミの生体密度は、いずれの月も体長の増加に伴って減少した。生体密度の季節的変化を見ると、同体長のツノナシオキアミでも、春季に小さく夏季に大きくなる傾向があった。また各月毎の平均生体密度をサンプル採集時の海水の密度で除した平均密度比も同様の季節的変化が見られ7月の方が6月より約1%大きかった。一方、音速比に関しても平均密度と同様に6月から7月にかけて約1%増加した。以上の測定により得られた各月毎の平均密度比、平均音速比を用いて音響理論散乱モデルからターゲットストレングス(TS)を推定し、季節によるTS変化を調べた。用いたモデルはオキアミを有限長のシリンダーに仮定する、有限長シリンダーモデルである。その結果、各月毎のツノナシオキアミのTSは同体長においても明確に異なっており、7月と9月ではそのTSは最大約5dB異なっていた。さらに平均密度比、平均音速比がともに約1%変化していた6月と7月では、算出されるTSが最大約3dB異なっていた。このことは、超音波反射の主要因である「うきぶくろ」を持たないオキアミのような生物のTSを推定する場合、単に体長を考慮する以上に密度比や音速比に適切な値を使わなければ、正確なTS推定ができないことを意味する。しかしこれら生体密度や生体内音速の季節的変化が、何に起因するかは今回の研究においては特定することができなかった。
• Development of Data Analysing System for Acoustic Fish Resource Survey

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for General Scientific Research (C)

  Date (from‐to) : 1994 -1995 

  Author : IIDA Kohji, MUKAI Tohru

   

  For the effective echo survey for fish resource estimation, the basic study has been conducted for two years and the following results were obtained.1.Data analysing system for echo survey using computer network was developed. It realized the parallel processing of data acquisition, analysis, and storage.2.High accuracy processing of the near bottom echo which is important for a demersal fish survey was investigated.3.Target strengths of juvenile swimbladder fish were measured. Juvenile fish often scatter acoustic waves well due to their resonance structure.4.The three-dimensional analysing method of scanning sonar which is effective tool for echo survey has developed.5.The new calibration procedure using standard sphere was proposed. It certifies to obtain the confident echoes from the standard target for calibration.6.Effective acoustic survey designs were discussed. The adaptive circumstance data, e.g., CTD data, Satellite image, ADCP data were gathered and generalized for echo data analysis.
• Research of pelagic fish stocks and living assessmemnt by satellite infrared images and quantitative eho sounder information of the sea near HOKKAIDO

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for General Scientific Research (B)

  Date (from‐to) : 1991 -1993 

  Author : SANO Noritatsu, ISHII Kiyoshiko, KOBAYASHI genji, AKIBA Yoshio, MUKAI Tohru, IIDA Kohji

   

  We substantiated the NOAA series with enough information to support an ocean survey by research ship.We also need to try to research when an where the fishing grounds witll shift and whether these stocksa are going to increase, etc. Accordingly we need to accumulate and analyze the data and information by the use of a quantitative echo sounder and the use of several ships at the same time in order to make the plankton's biomass clear. In this case it would be more effective if quantitative echo sounder information were standardized.The other way to plan for the efficient use of stock and of fishing ground production, is to make very accurate recordsof the fishing and oceanic conditions of sardine, the Japanese common squid, etc. At the same time we would neet to, with the cooperation of national or private research institutions, continue with the systematization of collection, management, and reporting of the data of fishing and oceanic conditions.
• 遊泳姿勢の変化に伴う魚体の超音波反射の変動に関する研究

  日本学術振興会：科学研究費助成事業 奨励研究(A)

  Date (from‐to) : 1992 -1992 

  Author : 向井 徹
• 魚およびプランクトンによる音響散乱に関する研究

  Date (from‐to) : 1985
• Studies on acoustic scattering signature of fish and zooplankton

  Date (from‐to) : 1985

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• 「海の学問」アクセス気軽に 北大水産院がネット教材公開 ５００テーマ、多言語対応

  Date : 2021/11

  Writer: Other than myself

  Program, newspaper magazine: 北海道新聞

  Paper
• 海中の情報収集、音波が最良 公開シンポで研究者３人講演

  Date : 2016/11

  Program, newspaper magazine: 函館新聞