Researcher Database

Kazushi Miyashita
Field Science Center for Northern Biosphere Aquatic Research Station

Researcher Profile and Settings


  • Field Science Center for Northern Biosphere Aquatic Research Station

Job Title

  • Professor


J-Global ID

Research Interests

  • 生態系サービス   Smart Fishery System   計量魚探   行動生態   バイオテレメトリー   バイオロギング   海洋生態系計測学   システム水産学   海洋生物資源計測学   音響生態学   海洋計量生態学   海洋生態系変動解析学   Fisheries and Plankton Acoustics   Marine Acoustical Ecology   Marine Quantitative Ecology   Marine Echosystem Change Analysis   

Research Areas

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

Academic & Professional Experience

  • 2022/04 - Today Hokkaido University Field Science Center for Northern Biosphere
  • 2011/07 - Today Hokkaido University Field Science Center for Northern Biospere Professor
  • 2007/04 - 2011/06 Hokkaido University Field Science Center for Northern Biospere Associate Professor
  • 2002/04 - 2007/03 Hokkaido University Field Science Center for Northern Biospere Associate Professor
  • 1998/03 - 2002/03 Hokkaido University Faculty of Fisheries Associate Professor
  • 1997/04 - 1998/03 Japan Marine Fishery Resources Reserch Center Resercher
  • 1996/05 - 1997/03 University of Tokyo Ocean Reserch Institute Postdoctoral Fellowships of Japan Society for the Promotion of Science(JSPS)
  • 1996/04 - 1996/04 University of Tokyo Ocean Reserch Institute Researcher (Postdoctoral Research fellow )


  • 1993/04 - 1996/03  University of Tokyo  Graduate School of Agricultual and Life Science (Ph. D)  Course of Aquatic bioresources
  • 1991/04 - 1993/03  Hokkaido University  Graduate School of Fisheries Sciences (Master)  Fisheries Course
  • 1987/04 - 1991/03  Hokkaido University  School of Fisheries Sciences  Fisheries Course

Association Memberships

  • 音響資源調査研究会   北海道総合ICT水産業フォーラム   サケ学研究会   バイオロギング研究会   Asian Society of Fisheries Acoustics(アジア水産音響学会)   北太平洋科学機構(PICES)   日本海洋学会   水産海洋学会   日本水産学会   海洋音響学会   

Research Activities

Published Papers

  • Yanhui Zhu, Kosuke Mizutani, Kenji Minami, Hokuto Shirakawa, Yohei Kawauchi, Huamei Shao, Makoto Tomiyasu, Yuka Iwahara, Tsutomu Tamura, Masahiro Ogawa, Kai Tatsuyama, Kazushi Miyashita
    Journal of Marine Science and Engineering 10 (7) 966 - 966 2022/07/14 
    The sandeel species (Ammodytes spp.) occupy a critical ecological position in connecting lower trophic levels to higher ones. However, they are strongly affected by the marine environment and their catch rates are trending downward. In this study, the target strength (TS) of sandeel species was measured in free-swimming specimens using a split-beam quantitative echo sounder with 38 and 120 kHz frequencies in a physically controlled environment. Parameters a and b used in the estimated TSmean–fork length (FL: 13.5–21.5 cm) equation were 53.7 and −124.3 dB at 38 kHz, and 71.3 and −153.2 dB at 120 kHz, respectively. The TS of the sandeel species were not proportional to the square of the FL but increased relatively rapidly with increasing body size. In addition, the mean and standard deviation of the swimming angle for the sandeel species from the acoustic data at 120 kHz were −2.2° and 7.7°, respectively, and most were in the −30° to 30°, range. Furthermore, TS was stronger at 38 kHz than at 120 kHz for all FL classes. The use of such frequency characteristics could facilitate the discrimination of fish species in the field and the sustainable assessment of sandeel species stocks.
  • 福島県さくら湖における計量魚群探知機を用いた藍藻類の音響計測の試み
    中森 陸, 南 憲吏, 白川 北斗, 朱 妍卉, 沖津 二朗, 大杉 奉功, 東 信行, 金 相曄, 谷田 一三, 黒田 充樹, 長岡 祥平, 佐藤 信彦, 宮下 和士
    Laguna 29 87 - 98 2022/03 [Refereed]
  • Mitsuki Kuroda, Kazushi Miyashita
    Environmental Biology of Fishes 0378-1909 2022/02/01 [Refereed]
  • Kenji Minami, Hokuto Shirakawa, Yohei Kawauchi, Huamei Shao, Makoto Tomiyasu, Yuka Iwahara, Yuichi Tsuda, Hideo Takahara, Yanhui Zhu, Kazushi Miyashita
    Canadian Journal of Fisheries and Aquatic Sciences 79 (2) 195 - 199 0706-652X 2022 [Refereed]
    Although chum salmon (Oncorhynchus keta) is an important fishery resource in Japan, acoustic methods cannot be applied to biomass estimation because the target strength (TS) is unknown. This study clarified the TS for each fork length (FL: 5.5–33.5 cm) of young chum salmon inhabiting the Japanese coastal area to the Bering Sea by measuring free-swimming fish. The size dependences of the TS values were TSmean = 20 log10 FL – 68.0, for both 38 and 120 kHz. This facilitated the estimation of biomass of young salmon using acoustic methods.
  • Koki Tsujii, Mayuko Otsuki, Tomonari Akamatsu, Kazuo Amakasu, Minoru Kitamura, Takashi Kikuchi, Amane Fujiwara, Hokuto Shirakawa, Kazushi Miyashita, Yoko Mitani
    Polar Biology 44 (12) 2289 - 2298 0722-4060 2021/12 [Refereed]
    The Chukchi Sea environment changes considerably in physical and biological conditions, driven by the expanding volume of warm Pacific summer water. These environmental changes can affect the migration timing of baleen whales in the southern Chukchi Sea. However, few studies have been conducted in this area to determine the migration timing of bowhead whales (Balaena mysticetus), the only baleen whale species endemic to the Arctic region. In this study, we conducted a fixed passive acoustic monitoring of bowhead whales in the southern Chukchi Sea from July 2012 to October 2015 and compared the occurrence patterns of vocalizations to physical and biological environmental factors. Bowhead whale calls were detected in fall/winter and spring during the ice-freezing and retreating periods, respectively. The fall migration timing of bowhead whales through the southern Chukchi Sea was delayed in the years when the timing of sea ice formation was late, and it formed increasingly later in the years 2013, 2014, and 2012, in that sequence. Moreover, the sea surface temperature decreased before freeze-up, which affected the timing of fall migration of bowhead whales. There was no clear relationship between the occurrence of bowhead whale calls and the abundance of prey, especially in spring, suggesting that most bowhead whales use the southern Chukchi Sea as a corridor during their spring northward migrations. However, the occurrence of bowhead whales and high abundance of zooplankton in October-November present the possibility that bowhead whales expand their feeding area in the southern Chukchi Sea.
  • Makoto Tomiyasu, Hokuto Shirakawa, Yuki Iino, Daichi Oshiyama, Masahiro Ogawa, Takashi Kitagawa, Hiromichi Mitamura, Nobuaki Arai, Yoshinori Miyamoto, Keiichi Uchida, Kenji Minami, Kazushi Miyashita
    Fisheries Research 242 106020 - 106020 0165-7836 2021/10 [Refereed]
  • Kenji Minami, Chihomi Kita, Hokuto Shirakawa, Yohei Kawauchi, Huamei Shao, Makoto Tomiyasu, Yuka Iwahara, Hideo Takahara, Takashi Kitagawa, Kazushi Miyashita
    Fisheries Research 240 105955 - 105955 0165-7836 2021/08 [Refereed]
  • Keiichi Fukaya, Hiroaki Murakami, Seokjin Yoon, Kenji Minami, Yutaka Osada, Satoshi Yamamoto, Reiji Masuda, Akihide Kasai, Kazushi Miyashita, Toshifumi Minamoto, Michio Kondoh
    Molecular Ecology 30 (13) 3057 - 3067 0962-1083 2021/07 [Refereed]
  • Mitsuki Kuroda, Yoshinori Tatsu, Yuya Ueda, Hokuto Shirakawa, Kenji Minami, Kazushi Miyashita, Makoto Tomiyasu
    Journal of Marine Science and Technology (Taiwan) 29 (2) 158 - 167 2021/05 [Refereed]
  • Development of a Biomass Assessment Method Using Fisheries Echo Sounder for Monit Sounder for Monitoring Whitebait Fisher oring Whitebait Fishery in Shizuoka Pr y in Shizuoka Prefecture, Japan
    Kenichi Kobayashi, Yanhui Zhu, Daichi Oshiyama, Kenji Minami, Hokuto Shirakawa, Kazushi Miyashita
    Journal of Marine Science and Technology (Taiwan) 29 (2) 168 - 174 2021/05 [Refereed]
  • Seasonal dynamics in fish distribution and abundance revealed by an acoustic sur acoustic survey in coastal waters of the Suzu Ar y in coastal waters of the Suzu Area, Kochi Pr ochi Prefecture, Japan
    Yanhui Zhu, Kenji Minami, Yuka Iwahara, Kentaro Oda, Koichi Hidaka, Osamu Hoson, Koji Morishita, Sentaro Tsuru, Masahito Hirota, Hokuto Shirakawa, Kazushi Miyashita
    Journal of Marine Science and Technology (Taiwan) 29 (2) 146 - 157 2021/05 [Refereed]
    NIPPON SUISAN GAKKAISHI 公益社団法人 日本水産学会 87 (2) 108 - 116 0021-5392 2021/03/15 [Refereed]

    Skipjack tuna Katsuwonus pelamis is known to aggregate around fish aggregating devices (FADs), and many ultrasonic biotelemetry investigations have been conducted around FADs. However, the investigation areas have been limited to the area around surface type FADs where receivers can be installed, and adequate tracking cannot be achieved. To clarify the behavioral ecology of skipjack in more detail, it is necessary to carry out extensive and long-term observations. We have developed a fishing boat-mounted receiving system that combines an ultrasonic biotelemetry receiving system and a data communication terminal. The developed system was installed on a fishing boat that operated around FADs in waters around Yonaguni Island, Okinawa, Japan, located in the upper Kuroshio Current. The effectiveness of behavioral investigation of skipjack around FADs was verified. As a result, we were able to expand the tracking area and received the locations of individuals by GPS and successfully tracked them for long periods. Furthermore, data were collected in an efficient manner by using an information and communication technology (ICT) network as a data acquisition method.

  • 水産資源を可視化する~直接計測、遠隔計測からバイオロギングまで~(新たな海の探求技術)
    海洋調査 142 20 - 26 2020/10 [Not refereed][Invited]
  • Spatial niche partitioning among three small cetaceans in the eastern coastal area of Hokkaido, Japan.
    Yuka Iwahara, Hokuto Shirakawa, Kazushi Miyashita, Yoko Mitani
    Marine Ecology Progress Series 209 - 223 2020/03 [Refereed][Not invited]
  • Mina Jimbo, Daisuke Mizuguchi, Hokuto Shirakawa, Koki Tsujii, Amane Fujiwara, Kazushi Miyashita, Yoko Mitani
    Polar Biology 42 (10) 1953 - 1958 0722-4060 2019/10 [Refereed][Not invited]
  • 野外環境下における人工海藻と漁網のニシン Clupea pallasii の産卵床としての活用
    富安信, 白川北斗, 小川真拓, 押山大智, 飯野祐樹, 宮下和士
    水産工学 55 (3) 2019/02 [Refereed][Not invited]
  • Huamei Shao, Kenji Minami, Hokuto Shirakawa, Yohei Kawauchi, Ryuichi Matsukura, Makoto Tomiyasu, Kazushi Miyashita
    Fisheries Research 214 110 - 116 0165-7836 2019 [Refereed][Not invited]
  • Can Swimming Depth Data from Multiple Pacific Herring Individuals Be Used to Estimate Characteristics if Their School? Verification by Micro Bio-Loggers
    Makoto Tomiyasu, Yuki Iino, Hokuto Shirakawa, Kazushi Miyashita
    Journal of Marine Science and Technology 2019 [Refereed][Not invited]
  • 屋内大型水槽を用いた自由遊泳するマアジのターゲットストレングス測定
    川内陽平, 南憲吏, 白川北斗, 宮下和士, 岩原由佳, 富安信, 小林基樹, 酒井猛, 邵花梅, 中川雅弘
    日本水産学会誌 85 (1) 2019/01 [Refereed][Not invited]
  • 気候変動下における日本系サケの持続可能な保全管理のあり方とその研究課題
    帰山雅秀, 荒木仁志, 宮下和士, 永田光博, 佐々木義隆, 浦和茂彦
    海洋と生物 40 (5) 459 - 466 2018/10 [Not refereed][Not invited]
  • Heterogeneous Wireless Sensor Networks for Underwater Biogeocenosis Monitoring
    Takahiro Fujiwara, Shinsuke Konno, Hitoshi Gotoh, Hiroyuki Kawai, Kazushi Miyashita, Takao Moriya
    Proceedings of the Workshop on Smart City Based on Ambient Intelligence (SCAI 2018) 2018/08 [Refereed][Not invited]
  • 環境変動下におけるサケの持続可能な資源管理:国際サーモン年に向けたプロローグ
    浦和茂彦, 荒木仁志, 宮下和士, 永田光博, 佐々木義隆, 帰山雅秀
    海洋と生物 40 (4) 315 - 318 2018/08 [Not refereed][Not invited]
  • Koji Miyoshi, Yasuhiro Kuwahara, Kazushi Miyashita
    Fisheries Science 84 (2) 349 - 355 1444-2906 2018/03/01 [Refereed][Not invited]
    The Northern Pacific sea star Asterias amurensis has a major negative impact on scallop mariculture. In northern Japan, fishermen clean up sea stars before releasing young scallops in the mariculture field however, new sea stars constantly invade the field from outside areas to feed on scallops. Thus, it is important to determine the migration speed and seasonal behavioral patterns of the Northern Pacific sea star to implement effective density control measures. Here, we set out to quantify these parameters using acoustic telemetry. In a rearing experiment, acoustic transmitters were retained on sea stars for up to 71 days using nylon fishing line. In the field experiment, we showed that the moving distance of the Northern Pacific sea star over a 1-week period was significantly further in spring (90.9 ± 49.9 m) than in summer (25.1 ± 18.9 m), and that the moving speed was significantly faster in spring (18.1 ± 15.2 m/day) than in summer (4.3 ± 9.1 m/day). Our results are the first to present the two-dimensional movement of Northern Pacific sea star individuals in spring and summer. We suggest that sea star extermination practices should be extended beyond the immediate culture area.
  • Makoto Tomiyasu, Hokuto Shirakawa, Yuki Iino, Kazushi Miyashita
    Fisheries Science 84 (1) 79 - 89 1444-2906 2018/01/01 [Refereed][Not invited]
    Pacific herring Clupea pallasii inhabiting around Japan migrate to coastal areas to spawn and are often caught by gill and set nets of coastal fisheries. For sustainable resource management, it is necessary to understand the behavioral patterns of such spawning migration in coastal spawning grounds. In this study, the migration of herring found in the Akkeshi region in eastern Hokkaido was revealed using acoustic telemetry. Individuals showed two movement patterns, viz. migration to Akkeshi Lake and remaining in Akkeshi Bay. For those migrating, most individuals entered the lake within 12–48 h. Two individuals reached the end of the lake within 1–3 days, and herring eggs and individuals in the process of spawning were found there. Consequently, this migration is likely related to spawning in the lake. The timing of migration to the lake appeared to be related to tidal dynamics. For those remaining in the bay, pings were detected at several locations, but none in any area beyond the relatively short period of 1–4 days. It is therefore possible that individuals moved more widely and quickly than the detection range of the receiver and the frequency of the survey in the bay.
  • Midori Ishii, Hiroto Murase, Yoshiaki Fukuda, Kouichi Sawada, Toyoki Sasakura, Tsutomu Tamura, Takeharu Bando, Koji Matsuoka, Akira Shinohara, Sayaka Nakatsuka, Nobuhiro Katsumata, Makoto Okazaki, Kazushi Miyashita, Yoko Mitani
    Mammal Study 42 (4) 191 - 199 1348-6160 2017/12/01 [Refereed][Not invited]
    In this study, we investigated the diving behavior of sei whales relative to the vertical distribution of their potential prey in the western North Pacific during the summer of 2013. Acoustic time-depth transmitters were attached to two sei whales for 10.2 and 32.0 h, respectively. The vertical distribution and density (expressed as the volume backscattering strength, SV) of their potential prey were recorded by an echosounder. Diving behavior was classified into two shapes: U-shaped and V-shaped. For both individuals, U-shaped diving was associated with higher SV values than V-shaped diving and the frequency of U-shaped diving increased from late afternoon until sunset. During the daytime, dense scattering layers (presumably zooplankton) were distributed at approximately 40 m and they then migrated toward the surface around sunset. The diving depth of the whales followed the diel migration of the scattering layers and the diving was concentrated in these layers when the density became high. The results of this study indicate that sei whales change their diving depth and shapes in response to the diel vertical migration of their potential prey.
  • Yuka Iwahara, Yoko Mitani, Kazushi Miyashita
    PACIFIC SCIENCE 71 (3) 303 - 318 0030-8870 2017/07 [Refereed][Not invited]
    Hydrographic, hydroacoustic, and cetacean visual surveys were conducted using a quantitative echosounder to estimate environmental factors influencing migration timing and distribution of Pacific white-sided dolphins (Lagenorhynchus obliquidens) in the Tsugaru Strait (nonbreeding area) and Funka Bay (breeding area) near Hokkaido, Japan. Higher numbers of dolphins were observed in the Tsugaru Strait during May and June and in Funka Bay during June, July, and August. Potential prey were observed in the Tsugaru Strait in May, June, and August, but they may not have been of a suitable size in August, which may explain absence of the dolphins in that month. In Funka Bay, potential prey were abundant in May, but dolphins may have been absent because of small prey size and low water temperature. In a smaller-scale analysis, the -relationship between dolphins and prey was different in the two areas, with -dolphin distribution more closely associated with prey distribution in the Funka Bay breeding area. This difference may have resulted from mothers needing to feed more frequently during lactation. These data should serve as an important foundation for estimating environmental factors impacting small cetaceans around Japan as well as changing environmental factors during the cetacean life cycle.
  • Kentaro Honda, Nobuyuki Takahashi, Keiichi Yamamoto, Haruka Kagiwada, Yuichi Tsuda, Yoko Mitani, Kazushi Miyashita
    ICHTHYOLOGICAL RESEARCH 64 (3) 357 - 364 1341-8998 2017/07 [Refereed][Not invited]
    Behavior of adult Parahucho perryi was examined using bio-logging and acoustic telemetry concurrently in the Bekanbeushi River system, eastern Hokkaido, Japan, in 2009 and 2010. Based on 46.1-87.9 h data from five P. perryi (69.0-80.0 cm fork length) caught from Lake Akkeshi, they used upstream (n = 2), midstream (n = 3), and downstream (n = 4) habitats. Large variability in diel activity and depth occupation existed in each stream habitat; however, fish in the downstream habitat tended to be more active than those in the upper habitats and mainly occupied shallower depths than mean bottom depth in this habitat.
  • Huamei Shao, Kenji Minami, Hokuto Shirakawa, Takashi Maeda, Toshiaki Ohmura, Yoshikazu Fujikawa, Norishige Yotsukura, Masahiro Nakaoka, Kazushi Miyashita
    JOURNAL OF MARINE SCIENCE AND TECHNOLOGY-TAIWAN 25 (3) 343 - 351 1023-2796 2017/06 [Refereed][Not invited]
    Acoustic methods can be used to assess seaweed meadows. The accuracy of the methods is a key factor in the estimation of seaweed distribution and conditions. We obtained and verified thickness and spatial distribution values measured using an echo sounder. We determined the thickness of seaweed growing in the coastal waters off Higashidoori-mura, Aomori, Japan on June 5-6, 2013. Acoustic data were collected using an on-board quantitative echosounder at 120 kHz. The thickness was also directly measured at 14 points. The root mean square error (RMSE) of the thickness determined by the acoustic and direct methods was calculated. A survey to determine the spatial distribution was performed in Miyako-shi, Iwate on July 18, 2014. The estimated spatial distribution was determined from the thickness data collected by the acoustic method of varied transect lines by changing transect orientation and intervals. The kelp forest distribution was also observed directly at 106 points. Then, the concordance rates of the visual observations and estimated spatial distribution were obtained. The RMSE of the acoustic and directly measured thickness of the kelp forests (Saccharina japonica), was 0.06 m, similar to the vertical resolution of the echosounder. The concordance rate between the acoustic and directly measured values was 92% when the maximum transect interval was 21 m. Smaller transect intervals yielded higher accuracy. High accuracy for the thickness and acoustically derived spatial distribution were obtained by the acoustic method when suitable thresholds were used, which has important applications for the evaluation of seaweed stands.
  • Tabitha C. Y. Hui, Yuka Morita, Yumi Kobayashi, Yoko Mitani, Kazushi Miyashita
    MARINE ECOLOGY-AN EVOLUTIONARY PERSPECTIVE 38 (3) 0173-9565 2017/06 [Refereed][Not invited]
    The number of harbour seals in Japan has been rebounding since protection began in the mid-1980s. With the increase in seal numbers, increased conflict with fisheries has occurred through depredation and the belief that seals compete with fisheries for prey. However, competition can only be determined if the prey species and quantities seals consume over time are known. We studied the diet of harbour seals in Erimo, site of the largest population of harbour seals in Japan, from 2011 to 2012 and assessed the degree of prey overlap with local fisheries. We used both hard parts and DNA techniques to identify prey items in seal scats, and compared these results to local fisheries data. A total of 46 prey occurrences was detected by both methods, of which 17 matched between techniques at least to the family level. Hard parts methods identified five incidences of prey undetected by DNA methods in five scats (one incidence per scat). DNA methods identified 24 additional prey occurrences in 13 scats, for which no hard part evidence for that prey had been found. This more than doubled the total number of prey occurrences across the 15 scats compared. Overall, the most frequently occurring harbour seal prey were walleye pollock (Theragra chalcogramma), sculpins and snailfishes. In contrast, the top three groups targeted by fisheries were codfishes, salmon and invertebrates. Many species common in the harbour seal's diet such as snailfishes and blennies were not targeted by fisheries. Fishes such as greenlings, sculpins, rockfishes and Japanese anchovy (Engraulis japonicus) were common in the diet of harbour seals, but made up a very small proportion of fisheries catches in Erimo. The importance of other prey species varied between seasons. Sculpins, greenlings and forage fishes were the top three prey groups for harbour seals in spring by percent modified frequency of occurrence, whereas the most important target groups by percentage mass caught by fisheries were codfishes, cephalopods and other invertebrates. Sculpins and rockfishes remained as important prey items for harbour seals in summer and autumn, in addition to codfishes, snailfishes and blennies. In contrast, the main groups caught by fisheries in summer were other fishes, particularly Japanese amberjack (Seriola quinqueradiata) and various species of sharks and eels, and invertebrates. By autumn, Erimo fisheries had focussed on catching salmon. Salmon were taken by harbour seals as well during this period, but at a relatively lower frequency compared to other prey groups. The results of our study show that although harbour seals consumed several of the prey species targeted by fisheries, the relative importance of these species to seals and fisheries and the seasons in which they were targeted were different.
  • Daisuke Saijo, Yoko Mitani, Takuzo Abe, Hiroko Sasaki, Chandra Goetsch, Daniel P. Costa, Kazushi Miyashita
    DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY 140 163 - 170 0967-0645 2017/06 [Refereed][Not invited]
    The Transition Zone in the eastern North Pacific is important foraging habitat for many marine predators. Further, the mesopelagic depths (200-1000 m) host an abundant prey resource known as the deep scattering layer that supports deep diving predators, such as northern elephant seals, beaked whales, and sperm whales. Female northern elephant seals (Mirounga angustirostris) undertake biannual foraging migrations to this region where they feed on mesopelagic fish and squid; however, in situ measurements of prey distribution and abundance, as well as the subsurface oceanographic features in the mesopelagic Transition Zone are limited. While concurrently tracking female elephant seals during their post-molt migration, we conducted a ship-based oceanographic and hydroacoustic survey and used mesopelagic mid-water trawls to sample the deep scattering layer. We found that the abundance of mesopelagic fish at 400-600 m depth zone was the highest in the 43 degrees N zone, the primary foraging area of female seals. We identified twenty-nine families of fishes from the mid-water trawls, with energy-rich myctophid fishes dominating by species number, individual number, and wet weight. Biomass of mesopelagic fishes is positively correlated to annual net primary productivity; however, at the temporal and spatial scale of our study, we found no relationship between satellite derived surface primary production and prey density. Instead, we found that the subsurface chlorophyll maximum correlated with the primary elephant seal foraging regions, indicating a stronger linkage between mesopelagic ecosystem dynamics and subsurface features rather than the surface features measured with satellites. Our study not only provides insights on prey distribution in a little-studied deep ocean ecosystem, but shows that northern elephant seals are targeting the dense, species-diverse mesopelagic ecosystem at the gyre-gyre boundary that was previously inferred from their diving behavior.
  • Makoto Tomiyasu, Wan-Yu Kao, Koki Abe, Kenji Minami, Taro Hirose, Michio Ogawa, Kazushi Miyashita
    ICES JOURNAL OF MARINE SCIENCE 73 (8) 2049 - 2057 1054-3139 2016/09 [Refereed][Not invited]
    During movement, the body angles of ribbonfish change, including a unique vertical swimming motion that influences their target strength (TS). In this study, we observed body angle changes in ribbonfish using an acceleration data logger and video recordings. Based on these data, variations in echo intensity in response to body angle changes were revealed using radiograph images of the swim-bladder and the respective TS values. The frequency of a body angle >60 degrees was 57.78% peak at 77 degrees. The swimbladders were found to be slender ellipses inclined 3-4 degrees upward from the body axis. The TS peaked (about -30 dB for the average pre-anal length of 223.9 +/- 21.8 mm) when the body angle was horizontal or inclined 2-3 degrees downward. The TS decreased substantially when the body angle was vertically inclined. From about 10 degrees upward inclination to vertical, the TS fluctuated between -50 and -60 dB. In a comparison of the average TS values among body angle categories, the TS values for body angles grouped as 'vertical' (between 60 degrees and 90 degrees), showing static mode activity patterns in video recordings, were low (-55.7 +/- 3.9 dB, Mean +/- SD), whereas those for the horizontal body angle (between 0 degrees and 30 degrees) category, comprising the active mode, were high (-47.0 +/- 8.7 dB) (P-value < 0.01). In the natural habitat, ribbonfish are known to gather at the sea floor during the daytime. In contrast, at night they disperse and move actively while foraging. Consequently, their echo intensities in natural habitats change substantially in response to their diel changes in behavioural ecology. Additional measurements or theoretical models considering the influence of ribbonfish behaviour should be undertaken as a result of this study.
  • Koki Tsujii, Mayuko Otsuki, Tomonari Akamatsu, Ikuo Matsuo, Kazuo Amakasu, Minoru Kitamura, Takashi Kikuchi, Kazushi Miyashita, Yoko Mitani
    ICES JOURNAL OF MARINE SCIENCE 73 (8) 2085 - 2092 1054-3139 2016/09 [Refereed][Not invited]
    Fin whales (Balaenoptera physalus) undergo seasonal migration in the Arctic Sea. Because their migration and distribution is likely affected by changes in global climate, we aimed to examine the migration timing of fin whales, and the relationship with prey availability within the oceanographic environment of the Arctic Sea, using passive and active acoustic monitoring methods. Automatic Underwater Sound Monitoring Systems were deployed in the southern Chukchi Sea from July 2012 to 2014 to determine the acoustic presence of fin whales. Furthermore, water temperature and salinity were recorded by a fixed data logger. An Acoustic Zooplankton Fish Profiler was additionally deployed to estimate prey abundance through backscattering strength. Sea ice concentrations were obtained by remote sensing data. Fin whale calls were automatically detected using a custom-made software, and the per cent of half-hours containing calls were counted. Fin whale calls were detected from 4 August to 20 October 2012 (78 d) and 25 July to 1 November 2013 (100 d). The extended period of acoustic presence of fin whales during 2013 when compared with 2012 is likely related to a longer ice-free period during 2013. Furthermore, generalized linear model analyses showed that half-hour periods containing calls increased with a rise in water temperature and zooplankton abundance during the initial call presence period, while they decreased with a decrease in water temperature and salinity during the end of the call presence period. Our results suggest that the rise in water temperature and zooplankton abundance affect the timing of migration of fin whales in away that is consistent with the expansion of their suitable habitats and the extension of their presence in the Arctic Sea.
  • Yuka Iwahara, Amane Fujiwara, Keizo Ito, Kazushi Miyashita, Yoko Mitani
    POLAR SCIENCE 10 (2) 173 - 176 1873-9652 2016/06 [Refereed][Not invited]
    Gray whales (Eschrichtius robustus) are distributed within the productive neritic and estuarine waters of the North Pacific Ocean, the Bering Sea, and adjacent waters of the Arctic Ocean. They migrate to high-latitude feeding grounds each spring. Their main feeding grounds in the Arctic include the Chirikov Basin, the northeastern Chukchi Sea from Pt. Hope to Cape Lisburne and Pt. Lay to Pt. Barrow, and the northwestern Chukchi Sea along the Chukotka coast. Although sightings are rare in the Canadian Beaufort Sea, we observed three gray whales in two groups in this area in September 2014. A mud plume was observed near one of the whales, suggesting the animal had been feeding. In the Alaskan Beaufort Sea, large-scale monitoring of the distributions of marine mammals has been continuously conducted since 1979; however, there has been less monitoring in the Canadian Beaufort Sea. Therefore, it is necessary to record opportunistic sightings, such as those described here. (C) 2016 Elsevier B.V. and NIPR. All rights reserved.
  • Salaheddine El Ayoubi, Kamal Mamza, Tadanori Fujino, Koki Abe, Kazuo Amakasu, Kazushi Miyashita
    FISHERIES SCIENCE 82 (3) 417 - 423 0919-9268 2016/05 [Refereed][Not invited]
    The target strength (TS) patterns of Sardina pilchardus and Sardinella aurita at 38 and 120 kHz were estimated by a prolate-spheroid model, using measurements of swimbladder length and width. The ratio of swimbladder length to total length (TL) was similar in both species, however the ratio of swimbladder width to TL was smaller and more variable for S. aurita. Assuming a normal distribution of fish swimming orientation angle (theta (fish)) with mean +/- A standard deviation (SD) of 0 +/- A 10A degrees, the normalized (by TL) average TS (b (20)) was estimated to be -64.0 dB (38 kHz) and -65.2 dB (120 kHz) for S. pilchardus, and -66.2 dB (38 kHz) and -67.2 dB (120 kHz) for S. aurita. Compared with currently applied b (20) values at 38 kHz, our results under four different theta (fish) assumptions (0 +/- A 10A degrees, 0 +/- A 15A degrees, -5 +/- A 10A degrees, and -5 +/- A 15A degrees) were 6-9 dB higher for S. pilchardus and 5-7 dB higher for S. aurita. This suggests four- to eightfold overestimation risk for S. pilchardus and three- to fivefold overestimation risk for S. aurita when using the currently applied b (20) values.
  • Satoshi Yamamoto, Kenji Minami, Keiichi Fukaya, Kohji Takahashi, Hideki Sawada, Hiroaki Murakami, Satsuki Tsuji, Hiroki Hashizume, Shou Kubonaga, Tomoya Horiuchi, Masamichi Hongo, Jo Nishida, Yuta Okugawa, Ayaka Fujiwara, Miho Fukuda, Shunsuke Hidaka, Keita W. Suzuki, Masaki Miya, Hitoshi Araki, Hiroki Yamanaka, Atsushi Maruyama, Kazushi Miyashita, Reiji Masuda, Toshifumi Minamoto, Michio Kondoh
    PLOS ONE 11 (4) e0153291  1932-6203 2016/04 [Refereed][Not invited]
  • Shiori Sonoki, Huamei Shao, Yuka Morita, Kenji Minami, Jun Shoji, Masakazu Hori, Kazushi Miyashita
    PLOS ONE 11 (3) 1932-6203 2016/03 [Refereed][Not invited]
    Eelgrass beds are an important source of primary production in coastal ecosystems. Understanding seasonal variation in the abundance and distribution of eelgrass is important for conservation, and the objectives of this study were to 1) monitor seasonal variation in eelgrass beds using an acoustic monitoring method (Quantitative echo sounder) and 2) broadly quantify the carbon circulation function. We obtained acoustic data of eelgrass beds in coastal areas north and east of Ikunojima Island. Surveys were conducted nine times over the 3-year period from 2011 to 2013 in order to monitor seasonal variation. Acoustic data were obtained and used to estimate the spatial distribution of eelgrass by geostatistical methods. To determine supporting services, we determined carbon sink and carbon fixation by eelgrass beds using data from the National Research Institute of Fisheries and Environment of Inland Sea (2011). The height and distribution of eelgrass beds were at a maximum in May and at a minimum in November of each year. Distribution trends were different between the north and east areas. Supporting services showed the same patterns throughout the year. The area of distribution was considered to be coincident with the life history of eelgrass. Distribution differed by area and changed yearly due to the effects of bottom characteristics and wind direction. Quantifying the supporting services of eelgrass beds was shown to be useful for managing the conservation of coastal ecosystems.
  • Takahiro Takashima, Nozomi Okada, Hiroki Asami, Noboru Hoshino, Osamu Shida, Kazushi Miyashita
    FISHERIES SCIENCE 82 (2) 225 - 240 0919-9268 2016/03 [Refereed][Not invited]
    The sexual maturation process and reproductive biology of female Arabesque greenling Pleurogrammus azonus in the Sea of Japan, off the west coast of Hokkaido, was examined using histological observations of ovaries. Maturation of P. azonus was classified into seven phases based on the presence of nine oocyte stages, post ovulatory follicles, and residual unspawned ova. Although vitellogenesis of P. azonus begins annually in August, hydrated oocytes were present in September and likely occurred several times during the spawning season until November. However, few oocytes at the intermediate stages of development were found during the premature and spawning phases. Based on these observations, the maturation pattern of female P. azonus can be classified as "group-synchronous, spawning several batches in a single spawning season," as in other hexagrammid fish. The probability of maturation of female P. azonus depended on body size rather than age. The estimated length at 50 % maturity was approximately 240 mm in standard length (SL). The mean SL of age-1 females just before the spawning season varied yearly around the 50 % maturity length. Overall, these findings suggest that the growth of female P. azonus before the spawning season at age 1 year can markedly affect spawning biomass.
  • 計量魚群探知機による海洋生物のモニタリング.
    吉江直樹, 眞野能, 藤井直紀, 宮下和士, 富安信
    沿岸海洋研究 53 165 - 167 2016 [Refereed][Not invited]
  • バイオロギングによる海洋生物のモニタリング.
    沿岸海洋研究 53 169 - 172 2016 [Refereed][Not invited]
  • Wan-yu Kao, Makoto Tomiyasu, Ryuzo Takahashi, Michio Ogawa, Tarou Hirose, Kouhei Kurosaka, Sentarou Tsuru, Yasuhiro Sanada, Kenji Minami, Kazushi Miyashita
    Journal of the marine acoustics society of Japan 特定非営利活動法人 海洋音響学会 42 (4) 167 - 176 0916-5835 2015 [Refereed][Not invited]
    To ensure sustainable utilization of the hairtail (Trichiurus japonicus) fishery resources in the coastal and offshore waters of Japan, 15 acoustic surveys were conducted from 2007 to 2013 using a 38 kHz split-beam echo sounder. The hairtail was mainly distributed depth between 80 and 280 m in winter (particularly between 80–120 m), 60–280 m in depth (particularly between 120–160 m) in autumn, and 70–260 m in depth (particularly between 70–140 m) in summer. The average area backscattering coefficient (sa) was higher in winter and spring between 2008 and 2009; in the other years it was highest in autumn. The average sa was significantly influenced by depth, temperature, salinity, and turbidity in univariate analyses (p<0.05). However, in linear regression analyses, the average sa significantly increased only with increases in temperature and salinity, whereas the effects of depth and turbidity were not statistically significant.
  • 南憲吏, 安間洋樹, 濱野明, 中村武史, 村瀬昇, 東条斉興, 宮下和士
    海洋音響学会誌 42 1 - 10 2015 [Refereed][Not invited]
  • Takehisa Yamakita, Hiroyuki Yamamoto, Masahiro Nakaoka, Hiroya Yamano, Katsunori Fujikura, Kiyotaka Hidaka, Yuichi Hirota, Tadafumi Ichikawa, Shigeho Kakehi, Takahiko Kameda, Satoshi Kitajimal, Kazuhiro Kogure, Teruhisa Komatsu, Naoki H. Kumagai, Hiroomi Miyamoto, Kazushi Miyashita, Haruyuki Morimoto, Ryota Nakajima, Shuhei Nishida, Kou Nishiuchi, Shingo Sakamoto, Masayoshi Sano, Kenji Sudo, Hiroya Sugisaki, Kazuaki Tadokoro, Katsuhiko Tanaka, Yoshie Jintsu-Uchifune, Kentaro Watanabe, Hiromi Watanabe, Yumiko Yara, Norishige Yotsukura, Yoshihisa Shirayama
    MARINE POLICY 51 136 - 147 0308-597X 2015/01 [Refereed][Not invited]
    After the adoption of the Aichi Target, data accumulation and evaluation regarding biodiversity have progressed rapidly. The use of ecologically and biologically significant areas (EBSAs) criteria to evaluate important areas enables the identification of effective and prioritized areas for ecosystem management. This includes strategic environmental assessment and discussions aimed at establishing protected marine areas based on scientific data. This paper reviews previous and current ideas as well as the methods used, for the identification of EBSAs. In particular, the following issues are addressed: problems associated with different types of marine ecosystems in the Japanese Archipelago, such as seagrass and seaweed beds, coral reefs, offshore pelagic plankton, and deep-sea benthic ecosystems; and problems associated with the integration of multiple criteria that are not totally exclusive. Several candidate variables accounting for each of the 7 criteria used to identify ecologically important areas are presented. Data availability is the most important criterion that allowed for the comprehensive evaluation of different types of ecosystems in the same localities. In particular, for coastal ecosystems such as seagrass, seaweed beds, and coral reefs, it is possible to carry out broad spatial comparisons using variables representing most of these 7 criteria. Regarding methods for the quantitative evaluation of each criterion and their integration, application of these methods to kelp forest ecosystems in Hokkaido, Northern Japan is presented as a case study. (C) 2014 The Authors. Published by Elsevier Ltd.
  • Hiroshi Yamaguchi, Yoko Goto, Noboru Hoshino, Kazushi Miyashita
    FISHERIES SCIENCE 80 (4) 665 - 678 0919-9268 2014/07 [Refereed][Not invited]
    We examined growth of northern shrimp Pandalus eous in the Sea of Japan, off western Hokkaido, to improve estimations of catch-at-age for stock assessment. Multiple length frequency analysis based on length frequency data collected by a scientific research vessel was conducted to examine length-at-age in the shrimp population. Multi-normal distributions estimated using maximum likelihood indicated a good fit to length distributions. AIC values and regression analyses revealed annual growth variation and a decreasing trend in the length at several age classes in the shrimp population. We revised the method for estimating catch-at-age from the age-conversion table (ACT), which is a simple method for age determination, to age-length keys (ALK) calculated from the results of multiple length frequency analysis. Abundant year classes caught successively year after year could be more easily identified from the catch-at-age data computed using ALK than by using ACT. Our results suggested not only that the mean size of commercial landings fluctuated based on changes in age composition but also that a decrease in the length-at-age in the population influenced the consistent size decrease of commercial landings.
  • Kenji Minami, Naoki Tojo, Hiroki Yasuma, Yusuke Ito, Takahiro Nobetsu, Shin-ichi Fukui, Kazushi Miyashita
    FISHERIES SCIENCE 80 (3) 405 - 413 0919-9268 2014/05 [Refereed][Not invited]
    In the Shiretoko Peninsula, a World Natural Heritage site, the sustainable management of kelp forests has drawn public attention because of the economic and ecological importance of kelp. We spatially estimated the distributions of kelp forests in the Shiretoko Peninsula before and after harvest. Field surveys were conducted in coastal waters (23.74 km(2)) at the ends of July and August 2008, immediately before and after harvest. Data on the presence or absence and thickness of the kelp forests were collected via acoustic observation. The data were interpolated using geostatistical methods. Before harvest, the kelp forests were continuously distributed over 5.64 km(2) (thickness 33-132 cm), especially near the north part of the study area. After harvest, they were sparsely distributed over 2.73 km(2) (thickness 35-105 cm). In the southern part of the study area, the influence of harvests was observed as declines in forest area. In addition, relatively thickly forested areas formed the majority of the part most likely to be harvested. Selective harvesting for area and size was confirmed though quantitative mapping of kelp forests. The quantitative mapping of both the distribution and harvest of kelp forests was successful.
  • Kentaro Honda, Haruka Kagiwada, Nobuyuki Takahashi, Kazushi Miyashita
    Ichthyological Research 61 (2) 142 - 151 1341-8998 2014/04/01 [Refereed][Not invited]
    The behavior of endangered adult Sakhalin taimen Parahucho perryi was tracked during 2008–2010 using acoustic telemetry in the Bekanbeushi River system, which flows through eastern Hokkaido, Japan. Movement distances per unit time of tracked P. perryi were compared between mid- and downstream habitats. Results indicated that movement distances were significantly longer in downstream habitats during all seasons. The movement distances in each stream decreased from spring to autumn. Moreover, tracked P. perryi exhibited crepuscular movement patterns however, patterns were less pronounced in downstream habitats than in up- and midstream habitats. These findings strongly suggested that adult P. perryi exhibit nearly distinctive movement patterns across stream habitats thus, fish may adopt different foraging tactics in each stream habitat. Fish moved more frequently in spring, which included the post-wintering and post-spawning season, most likely to search for food and more desirable habitat for recovery.
  • Osamu Shida, Yukio Mihara, Takashi Mutoh, Kazushi Miyashita
    FISHERIES SCIENCE 80 (2) 173 - 179 0919-9268 2014/03 [Refereed][Not invited]
    The southwestern Pacific coast of Hokkaido is the main spawning ground for the Japanese Pacific stock of walleye pollock Theragra chalcogramma. A commercial gillnet fishery targeting spawning adult pollock in this area mainly operates from October to January to coincide with the migration of adult pollock from the feeding ground. Given the results of acoustic surveys, and changes in the proportion of the monthly total catch that was monthly walleye pollock caught by the commercial gillnet fishery, it is thought that the timing of walleye pollock spawning migration to the Donan area varies among years and that the pollock catch of the gillnet fishery clearly reflects changes in pollock abundance in this area. A time series of interannual variability in catch data from 1980 to 2005 suggested that adult pollock migrated and concentrated on their spawning ground later in the 1980s and after 2000 than in the 1990s. Such decadal-scale shifts are presumably caused by climatic changes (e.g., in water temperature) in the Oyashio region. These shifts affect the gillnet fishery through differences in monthly unit prices of pollock and changes in the formation of fishing grounds. These scientific findings can aid the establishment of rules for more efficient walleye pollock resource management under the total allowable catch system.
  • Yohei Kawauchi, Masayuki Chimura, Takashi Mutoh, Masamichi Watanobe, Hokuto Shirakawa, Kazushi Miyashita
    FISHERIES SCIENCE 80 (2) 139 - 149 0919-9268 2014/03 [Refereed][Not invited]
    We examined factors affecting the vertical distribution of juvenile walleye pollock during "the second critical period" (i.e. the transition period of prey size) in and around Funka Bay, Hokkaido, Japan. During the day, small juveniles (< 30 mm) were distributed mainly in shallow, warm, and low-salinity water within the bay, whereas larger ones (a parts per thousand yen30 mm) occurred in deeper, cold and saline water. During the night, the large juveniles migrated to shallower depths. Outside the bay, small- and large-sized juveniles were distributed in water masses of similar physical properties during the daytime, whereas during the nighttime, most of the juveniles moved to shallower depth, and some juveniles dived to deeper water mass. Dietary analysis revealed that large juveniles fed on large copepods (a parts per thousand yen0.5 mm in body width) more than small juveniles did. The composition of zooplankton in our survey area showed that large-sized copepods often occurred in deeper saline water. From these results, there is a possibility that juvenile pollock inside and outside Funka Bay occupied different water masses preferable for each feeding advantage.
  • 根室海峡羅臼沖における鯨類目視調査.
    藤田弥生, 大槻真友子, 宮下和士, 三谷曜子, 北夕紀
    東海大学紀要・生物学部 3 11 - 17 2014 [Not refereed][Not invited]
  • 石狩川上流におけるサケOncorhynchus ketaの2012年の自然産卵状況.-大規模放流個体群回帰2年目の報告-.
    有賀誠, 山田直佳, 伊藤洋満, 有賀望, 宮下和士
    旭川市博物科学館研究報告 6 21 - 36 2014 [Not refereed][Not invited]
    NSUGAF 日本水産學會 79 (3) 345 - 354 0021-5392 2013/05/15 
    The purpose of this study was to clarify the acoustic scattering properties of juvenile jack mackerel Trachurus japonicus, based on theoretical calculations and target strength (TS) measurements for determining the optimum frequency with which to estimate the biomass using a scientific echosounder. The theoretical TS of the juvenile jack mackerel was estimated using a scattering model (PSM) based on the morphometry of the swimbladder. The fork length (L) ranged from 7.5 to 12.9 cm (26 specimens). These theoretical TS values corresponded with ex situ measurement results of the TS. The normalized max. TScm and mean TScm, i.e. the TS normalized by the square of body length (L, cm), at each frequency corresponding to those commonly used for acoustic surveys (18, 38, 50, 70, 120, and 200 kHz), ranged from −66.2 to −68.4 dB, and −68.7 to −69.9 dB, respectively. In addition, these TS differences between pairs of frequencies (ranging from 18 kHz to 200 kHz) within the tilt angle distributions having a mean of 0° and standard deviation of 15° were relatively small.
  • 北海道北部沿岸域におけるなまこけた網の漁獲効率の推定.
    佐野稔, 前田圭司, 高柳志朗, 和田雅昭, 畑中勝守, 菊池肇, 宮下和士
    北水試研報 84 1 - 9 2013 [Not refereed][Not invited]
  • 石狩川上流におけるサケOncorhynchus ketaの2011年の自然産卵状況.-大規模放流個体群回帰回帰1年目の報告-.
    有賀誠, 山田直佳, 伊藤洋満, 有賀望, 宮下和士
    旭川市博物科学館研究報告 5 47 - 57 2013 [Not refereed][Not invited]
  • Safruddin, Yohei Kawauchi, Yusuke Ito, Kenji Minami, Kazuhiro Itaya, Keiji Maeda, Ryuichi Matsukura, Koki Abe, Hiroki Yasuma, Kazushi Miyashita
    Journal of the marine acoustics society of Japan 40 329 - 338 2013 [Refereed][Not invited]
  • Spatial estimation of the kelp forest (Laminaria spp.) distributions in coastal waters of Osatsube Hokkaido, Japan, using acoustic method and geographic information system.
    Huamei Shao, Yusuke Ito, Kenji Minami, Hiroki Yasuma, Kazushi Miyashita
    GIS/Spatial Analyses in Fishery and Aquatic Sciences 5 133 - 150 2013 [Refereed][Not invited]
  • Ryuichi Matsukura, Kouichi Sawada, Koki Abe, Kenji Minami, Hiroshi Nagashima, Shiroh Yonezaki, Hiroto Murase, Kazushi Miyashita
    Nippon Suisan Gakkaishi (Japanese Edition) 79 (4) 638 - 648 1349-998X 2013 [Refereed][Not invited]
    The target strength (TS) of juvenile sandeel (3.1-7.7 cm in standard length, SL) was measured for various tilt angles (-30° to 30°) at 120 kHz, and was compared with the theoretical TS calculated using the theoretical sound scattering model. The maximum TS measured at the tilt angle of 0° ranged from -68.8 to -60.8 dB, whereas the range of the theoretical TS was from - 68.7 to - 61.5 dB. The difference of the measured and theoretical values of the maximum TS was -1.6 to 0.9 dB, and the TS patterns showed good agreement, particularly in the range of the main lobes, in the tilt angle (-10° to 10°). The theoretical model was used to calculate the TS under the same conditions where the specimens were collected. The correlation between the SL and the maximum TS is given by the equation: TS=43.1 log SL - 96.1.
  • 理論モデルとTS測定に基づくマアジ幼魚の音響散乱特性.
    中村武史, 濱野 明, 安部幸樹, 安間洋樹, 宮下和士
    日本水産学会誌 79 383 - 393 2013 [Refereed][Not invited]
  • Tadanori Fujino, Tsuneo Goto, Tsuyoshi Shimura, Hiroki Yasuma, Yongjun Tian, Hideaki Kidokoro, Shinya Masuda, Kazushi Miyashita
    Journal of Marine Science and Technology (Taiwan) 21 (1) 58 - 62 1023-2796 2013 [Refereed][Not invited]
    Egg abundance of Maurolicus japonicus, a dominant mesopelagic fish in the Japan Sea, was analyzed during 1981-2005 as an index of the spawning-adult abundance. There was a major change in egg abundance around 1988/1989, with negative anomalies occurring during 1981-1988 and positive anomalies occurring from l989. At about the same time (1986/1987), the Tsushima Current shifted from cold to warm conditions. Environmental indices were found to be positively correlated with egg abundance two years later. Our results suggest that the abundance of M. japonicus is affected by climatic regime shifts, and that it could be used as an indicator species.
  • Takahiro Takashima, Noboru Hoshino, Kazuhiko Itaya, Keiji Maeda, Kazushi Miyashita
    Nippon Suisan Gakkaishi (Japanese Edition) 79 (3) 383 - 393 1349-998X 2013 [Refereed][Not invited]
    There is a need to establish a method of determining age and to investigate the relationship between the age and body size of the Northern Hokkaido stock of the Arabesque greenling Pleurogrammus azonus. Therefore, we examined the method of age validation by using otoliths, and estimated the relationship between age and size. A mass-processing method was used to section the otoliths. The annual growth of otoliths was verified using edge-type analysis. The age of individual fish could be accurately validated by counting the number of outer edges of the translucent zones. Because of disagreement between the annual growth of otoliths and the formation of checks, the number of checks was considered unsuitable for age validation of the stock. Logistic growth models, which indicated differential asymptotic length by sex, were estimated as the age-size relationship of the stock. The growth of the Arabesque greenling was rapid up to 2 years of age, then slowed. We conclude that age validation is necessary for the stock because it is impossible to predict the age of the fish on the basis of size after 2 years of age.
  • Kentaro Honda, Haruka Kagiwada, Nobuyuki Takahashi, Kazushi Miyashita
    ECOLOGY OF FRESHWATER FISH 21 (4) 640 - 657 0906-6691 2012/10 [Refereed][Not invited]
    Behavioural tracking of endangered adult Sakhalin taimen (Parahucho perryi) by acoustic telemetry was conducted in the Bekanbeushi River system that flows through eastern Hokkaido in 20082010. A total of 39 tracked P. perryi showed extensive use of the river system, both upstream and downstream, regardless of the month or year. No tracked adult P. perryi stayed in the ocean for more than 1 day. Some of the fish (20%) dwelled in upstream habitat consistently from spring to autumn, while 40% of individuals showed wide utilisation of the entire upstream and downstream systems. Although 39.4% of tracked fish utilised two or more primary tributaries to the main river, 6.1% used only the main river system. Distinct variability was observed between individuals based on the proportion of time spent in each stream reach (up-, mid-, and downstream). A trend was observed in 2008 and 2010 showing that tracked fish moved to the upper stream reaches when water temperatures downstream increased. This trend was not observed in 2009 when the summer water temperature downstream was more than 2 degrees C below average when compared to 2008 and 2010. Our results suggest that adult P. perryi in the Bekanbeushi River system exhibit high behavioural plasticity, that is, the fish can select habitats based on their own individual requirements. Our results also demonstrate the importance of physical continuity among river reaches both upstream and downstream such that P. perryi does not experience barriers in moving to optimal habitats.
  • Hiroto Murase, Atsushi Kawabata, Hiroshi Kubota, Masayasu Nakagami, Kazuo Amakasu, Koki Abe, Kazushi Miyashita, Yoshioki Oozeki
    FISHERIES SCIENCE 78 (4) 761 - 773 0919-9268 2012/07 [Refereed][Not invited]
    The distribution pattern and biomass of the Japanese anchovy Engraulis japonicus in the offshore region of the western North Pacific (north of 35A degrees N and west of 170A degrees E) were studied using a quantitative echosounder. This is the first attempt at such a study in this region. Data were collected in summer from 2004 to 2007. The biomass was estimated using data collected at 38 kHz. Species compositions in the backscatterings from pelagic fish were assigned based on the results of trawl hauls taking account of sea surface temperature (SST). Japanese anchovy tended to be high density to the west of 153A degrees E and were distributed in an SST range of 9-24 A degrees C. Although the temporal and spatial coverage of the survey differed each year, at least 1.5-3.4 million tons of Japanese anchovy were present in the survey area between 2004 and 2007. To take account of the spatial coverage of the survey each year, the most reliable biomass estimate for this region in the time period was 3.4 million tons (coefficient of variation 0.22).
  • 石狩川上流におけるサケOncorhynchusketaの自然産卵.-大規模放流個体群回帰前の実態-
    有賀誠, 山田直佳, 伊藤洋満, 有賀望, 宮下和士
    旭川市博物科学館研究報告 4 35 - 46 2012/03 [Not refereed][Not invited]
  • K. Honda, T. Arai, S. Kobayashi, Y. Tsuda, K. Miyashita
    JOURNAL OF FISH BIOLOGY 80 (2) 408 - 426 0022-1112 2012/02 [Refereed][Not invited]
    Acoustic telemetry and microchemical analysis of otolith strontium-calcium ratios were used to evaluate how exotic brown trout Salmo trutta have responded to Japanese riverine environments of south-western Hokkaido by observing their migratory patterns. The existence of anadromous S. trutta was also verified. Most S. trutta caught in rivers for otolith analysis were freshwater residents (95.6%), whereas those caught in the sea were mainly smolts (91.3%), which had just migrated from rivers during spring. Anadromous S. trutta (n = 6) were captured in rivers and in the sea, confirming the existence of mature pre- and post-spawning fish. According to telemetry results, both mature and immature S. trutta used the river in winter, and their estimated sea-run timings showed individual differences. Through the combination of these two methods, migratory patterns on various spatio-temporal scales were observed. This first documentation of the presence of both male and female anadromous S. trutta in the same region within Japan indicated the risk of further colonization of exotic S. trutta via oceanic migration. (C) 2012 The Authors Journal of Fish Biology (C) 2012 The Fisheries Society of the British Isles Key words: acoustic tracking; alien species; anadromy; life history; migration; otolith chemistry.
  • Osamu Tamaru, Kazushi Miyashita, Nobuo Kimura, Yasuzumi Fujimori, Hideo Takahara, Teisuke Miura
    Bulletin of Fisheries Sciences, Hokkaido University 北海道大学大学院水産科学研究院 62 (3) 75 - 82 1346-1842 2012 [Not refereed][Not invited]
    In recent years in Japan, falling fish prices and rising fuel costs have worsened the economic conditions for many fisheries-dependent households. Many fishermen select the fishing ground in which they anticipate they can maximize their total catch, even when such grounds are far from their home harbor. As a result, fishermen have the potential to select a fishing ground in which they do not maximize their income. Especially the Japanese coastal squid jigging fishermen need to develop energy-saving squid jigging fishery practices, because of the high fuel consumption in comparison to other fisheries. By using the Management Simulation Method, we show that income fluctuations are caused by various factors. We used social factors and fishing ground factors in this simulation. According to the simulation results, small changes in social and fishing ground situations can result in changes in selection of the optimal fishing grounds. We conclude that the selection of fishing grounds by fishermen based only on their own knowledge and/or intuition might not result in choices that maximize their income, and it is necessary to develop objective methods to choose the fishing ground in which they can maximize their income.
  • Ko Fujioka, Alistair J. Hobday, Ryo Kawabe, Kazushi Miyashita, Yoshimi Takao, Osamu Sakai, Tomoyuki Itoh
    FISHERIES OCEANOGRAPHY 21 (4) 269 - 280 1054-6006 2012 [Refereed][Not invited]
    The arrival of the warm tropical Leeuwin Current (LC) into southern Western Australia (SWA) may influence the movement timing and foraging habitat of juvenile southern bluefin tuna (SBT). Seasonal and interannual changes in the strength of the LC lead to thermal differences and potential changes in food availability between tropical and temperate waters in SWA. This phenomenon could influence the habitat utilization of SBT in these summer grounds. Movement characteristics determined from SBT tagged with acoustic transmitters (N = 244) using cross-shelf lines of automated receivers for three summer-autumn seasons (2004/2005, 2005/2006, 2006/2007) in SWA revealed interannual variability. Each year, the eastward movements of tagged fish increased as temperatures increased, and fish left the region when temperatures exceeded 20.0 degrees C, a temperature indicative of the leading edge of the LC in SWA waters. Interannual fluctuations in the timing of movements were detected. When the LC was narrow and restricted to the shelf edge in 2004/2005, the distribution of SBT in shelf waters did not change before or after LC intrusion. In contrast, long distance eastward movements frequently occurred when the LC intrusion was spread wide over the continental shelf in 2005/2006 and 2006/2007. This suggests that, off SWA, juvenile SBT move quickly out of local foraging habitats defined by cool sub-tropical temperate waters ahead of the tropical LC intrusion, despite these waters not being physiologically limiting. These results suggest that the behavioural response of SBT may be related to changes in prey availability as a result of changes in oceanographic conditions.
  • 音響手法を用いたコンブ場の高さ計測
    南憲吏, 安間洋樹, 東条斉興, 伊藤祐介, 福井信一, 野別貴博, 宮下和士
    数理水産科学 9 62 - 74 2012 [Refereed][Not invited]
  • Kenji Minami, Akira Hamano, Naoki Tojo, Takeshi Nakamura, Hiroki Yasuma, Kazushi Miyashita
    Nippon Suisan Gakkaishi (Japanese Edition) 78 (2) 171 - 179 0021-5392 2012 [Refereed][Not invited]
    Sargassum beds play important ecological roles as nursery grounds, feeding grounds and hiding grounds for coastal fauna in Kuruminose, Yamaguchi, Japan (12 km 2). In this study, we tried to estimate the spatial distribution of a Sargassum bed using an acoustic method. For this purpose, binarization and geostatistical methods were used. The binarization provided the optimum thresholds to separate the bottom and head of the Sargassum bed. The bottom threshold and the head threshold were -22.4 dB, and -56.4 dB, respectively. The horizontal distribution was interpolated every 1 m 2 using kriging. The area of the Sargassum bed was estimated to be 1.94 km2, with thickness of 0.50 to 2.24 m. The Sargassum bed in the south-southeast of Kuruminose was thicker and larger than that near Kuruminose, suggesting that the south-southeast Sargassum bed is important for the coastal ecosystem in Kuruminose. The estimated thickness and distribution corresponded with those by direct observation by diving and underwater TV camera, suggesting that acoustic measurement is adequate for estimating the spatial distribution of Sargassum beds.
  • Minoru Sano, Keiji Maeda, Siro Takayanagi, Masaaki Wada, Katsumori Hatanaka, Shinichi Motomae, Hajime Kikuchi, Kazushi Miyashita
    NIPPON SUISAN GAKKAISHI 77 (6) 999 - 1007 0021-5392 2011/11 [Refereed][Not invited]
    The populations of sea cucumber Apostichopus armata in four coastal areas of northern Hokkaido, Japan were estimated based on data collected between June and September 2008 using two methods: the initial population was calculated from CPUE (catch per dredge-net) against cumulative catch (DeLury method), and from the catch against dredged area (swept-area method). The estimation obtained using the DeLury method did not reflect the actual population size in the two areas as the data requirements were insufficient: the slope of linear regression of CPUE on cumulative catch was gentle or the coefficient of determination was low. The estimates using the swept-area method seemed to be lower than the actual population size for all the areas because the catch efficiency was assumed as 1; however, sampling errors were low, as the estimates were based on a large number of sampling data collected directly from a wide area. We conclude that the swept-area method provides a more accurate assessment of sea cucumber stock in the coastal areas of northern Hokkaido than the DeLury method.
  • Hiroto Murase, Atsushi Kawabata, Hiroshi Kubota, Masayasu Nakagami, Kazuo Amakasu, Koki Abe, Kazushi Miyashita, Yoshioki Oozeki
    JOURNAL OF MARINE SCIENCE AND TECHNOLOGY-TAIWAN 19 (3) 267 - 272 1023-2796 2011/06 [Refereed][Not invited]
    Effect of the depth-dependent target strength (TS) on biomass estimation of Japanese ahcovy was examined by using following four TS models: (1) TS = 20logL(1)-71.9, (2) TS = 20logL(1)-72.5, (3) TS = 20logL(1)-(20/3)log(l+z/10)-67.6 and (4) TS = 20logL(1)-(2013)log(l+z/10)-64.7, where L, and z represent total length (cm) and depth (m), respectively. (1) and (2) have been used in conventional fisheries resources surveys; (3) and (4) take account of depth-dependent TS. Because (1)-(3) were based on in-situ measurement, pitch angles of individuals used in the models were not known. Pitch angle is assumed 00 (+/- 10 degrees std) in (4). Biomass estimated by (3) was 82% and 73% of (1) and (2), respectively. Biomass estimated by (3) was 195% of (4). The results indicated that the effect of the pitch angle on the biomass estimation could be large even if the effect of the depth-dependent TS was taken account. Mean distribution depth can be used as a value for z.
  • Naoki Tojo, Kenji Minami, Ryuichi Matsukura, Yohei Kawauchi, Tetsuichiro Funamoto, Masayuki Chimura, Akira Nishimura, Kazushi Miyashita
    JOURNAL OF MARINE SCIENCE AND TECHNOLOGY-TAIWAN 19 (3) 294 - 301 1023-2796 2011/06 [Refereed][Not invited]
    This study focused on euphausiid distribution and biomass estimation over the coastal shelf of the Pacific coast of Hokkaido Japan in early summer 2008. Acoustic data were obtained in both day (6:00-18:00) and night (18:00-6:00) using a quantitative echosounder (EK60, Simrad) with two frequencies (120 and 38 kHz). Echoes of euphausiids were specified based on the Delta MVBS, calculated with seasonal theoretical target strength of Euphausia pacifica. The best-fit kriging models were used to quantitatively interpolate euphausiid distribution. The detected euphausiid biomass reached 38,278 t (> 15 gWWm(-2)), suggesting abundant prey for large fishes over study area. On the other hand, the distribution was spatially heterogeneous in produced GIS map, suggesting the spatially limited available prey. Observed day-night difference of estimated biomass was caused by spatial variability of diel movement of euphausiids. Acoustic dead zones and behavioral change in euphausiids may strongly influence biomass estimation in night in coastal shelf environment.
  • Yohei Kawauchi, Osamu Shida, Hiroya Okumura, Naoki Tojo, Hiroki Yasuma, Kazushi Miyashita
    JOURNAL OF MARINE SCIENCE AND TECHNOLOGY-TAIWAN 19 (3) 279 - 286 1023-2796 2011/06 [Refereed][Not invited]
    We examined the vertical distributions of walleye pollock Theragra chaleogramma juveniles for two size groups (smaller and larger than 30 mm) during the period of transition for feeding (PTF) and after this period in Funka Bay, Hokkaido, Japan. Samplings were conducted in May and June in 2006 and 2007, and water temperature and salinity were measured. The correlation between juvenile sizes and distributed depth was observed using net sampling. From this result, size groups were divided by depth. In addition, the distribution and abundance of juveniles were examined using acoustic data. In the PTF (May), juvenile size increased with increasing depth, and after the PTF (June), most juveniles descended. In the PTF, juveniles smaller than 30 mm in TL dominated above 43 m depth in 2006, while juveniles larger than 30 mm in TL dominated below 18 m depth in 2007. After the PTF, juvenile sizes were larger in 2006 than in 2007. The relationships between juvenile distributions and water masses in the PTF were analyzed, and it was found that surface water of coastal Oyashio water (S-CO) dominated in the layers where small juveniles were distributed, and that Oyashio water (OW) dominated in the layers where large juveniles were distributed.
  • Yusuke Ito, Hiroki Yasuma, Reiji Masuda, Kenji Minami, Ryuichi Matsukura, Saho Morioka, Kazushi Miyashita
    FISHERIES SCIENCE 77 (2) 161 - 167 0919-9268 2011/03 [Refereed][Not invited]
    The swimming angle of larval Japanese anchovy (Engraulis japonicus) was measured in a tank, and target strength (TS) was calculated using a theoretical scattering model. The mean swimming angle was 12.8A degrees (SD +/- 22.1). Increased speeds of flow led to increased mean swimming angles. The mean swimming angle at flow of 5 cm s(-1) was higher than at other speeds. TS values were estimated using a distorted-wave Born approximation model for two cases. Average values were 1-3 cm s(-1) (11.5A degrees A A +/- A 22.1) and 5 cm s(-1) (16.6A degrees A A +/- A 21.7) for cases 1 and 2, respectively. For case 1, TS ranged from -92.0 to -74.7 dB with a mean of -79.4 dB at 120 kHz. For case 2, TS ranged from -92.2 to -75.2 dB with a mean of -79.9 dB. The mean TS in case 2 was lower than that in case 1, with the maximum difference being 1.0 dB at 120 kHz (standard length 22.0 mm). However, there were no significant differences between the regression lines of cases 1 and 2. Thus, changes in flow speed altered the swimming angle of larval Japanese anchovy, but had little influence on TS.
  • 2003,2005~2009年,練習船おしょろ丸からの目視調査によるシャチ(Orcinus orca)の写真識別カタログ
    三谷曜子, 岡崎宏美, 関口圭子, 宮下和士
    北海道大学水産科学研究彙報 61 (2/3) 65 - 74 2011 [Not refereed][Not invited]
  • 石狩川中流域におけるサケOncorhynchus ketaの自然産卵
    有賀誠, 山田直佳, 有賀望, 津田裕一, 本田健太郎, 宮下和士
    旭川市博物科学館研究報告 3 63 - 73 2011 [Not refereed][Not invited]
  • Minoru Sano, Keiji Maeda, Siro Takayanagi, Masaaki Wada, Katsumori Hatanaka, Shinichi Motomae, Hajime Kikuchi, Kazushi Miyashita
    Nippon Suisan Gakkaishi (Japanese Edition) 77 (6) 999 - 1007 0021-5392 2011 [Refereed][Not invited]
    The populations of sea cucumber Apostichopus armata in four coastal areas of northern Hokkaido, Japan were estimated based on data collected between June and September 2008 using two methods: the initial population was calculated from CPUE (catch per dredge-net) against cumulative catch (DeLury method), and from the catch against dredged area (swept-area method). The estimation obtained using the DeLury method did not reflect the actual population size in the two areas as the data requirements were insuffcient the slope of linear regression of CPUE on cumulative catch was gentle or the coeffcient of determination was low. The estimates using the swept-area method seemed to be lower than the actual population size for all the areas because the catch effciency was assumed as 1 however, sampling errors were low, as the estimates were based on a large number of sampling data collected directly from a wide area. We conclude that the swept-area method provides a more accurate assessment of sea cucumber stock in the coastal areas of northern Hokkaido than the DeLury method.
  • Hiroshi Yamaguchi, Shuichi Nishiuchi, Shiro Takayanagi, Kazushi Miyashita
    Nippon Suisan Gakkaishi (Japanese Edition) 77 (5) 809 - 821 0021-5392 2011 [Refereed][Not invited]
    aimed to estimate the size selectivity of the shrimp pot for the northern shrimp Pandalus eous by the SELECT analysis method. Comparative fishing experiments were conducted by using shrimp pots of different mesh sizes (bar length: 13.99, 15.30, 16.84, and 19.13 mm) with control pots of 5.33 mm. We obtained size selective curves for non-ovigerous and ovigerous shrimps. The carapace lengths of 50% of the non-ovigerous shrimps caught (L 50) with mesh sizes of 13.99, 15.30, 16.84, and 19.13 mm were 20.10, 22.75, 26.25, and 28.64 mm, respectively. The carapace lengths of ovigerous shrimps caught with a mesh size of 19.13 mm were significantly different from those of shrimps caught with a non-selective mesh size of 5.33 mm. Therefore, mesh size of less than 19.13 mm was nonselective for ovigerous shrimps. The L50 of ovigerous shrimps caught with a mesh size of 19.13 mm was 25.74 mm. The percentage changes in the total catch and income were calculated when mesh sizes of more than 15.30 mm were used: they decreased by 11.8% and 9.5%, respectively, when the mesh size was modified to 16.84 mm, while they decreased by 31.2% and 27.8%, respectively, when the mesh size was modified to 19.13 mm.
  • K. Honda, H. Kagiwada, N. Tojo, K. Miyashita
    JOURNAL OF FISH BIOLOGY 77 (7) 1526 - 1541 0022-1112 2010/11 [Refereed][Not invited]
    The study identified seasonal habitat use by endangered adult Sakhalin taimen Hucho perryi and the environmental characteristics of their habitat (water depth, amount of riparian forest and sinuosity). Fifteen adult H. perryi with acoustic tags were tracked by towing an acoustic receiver with a canoe in the Bekanbeushi River system in eastern Hokkaido Island, Japan, during each month from late April to late November 2008. Individuals mainly used midstream (shallower than downstream) habitats in all seasons. These locations were generally characterized by relatively dense riparian forests and high sinuosity, indicating the presence of pools. In spring, individuals used habitats with less riparian forest cover compared to mean value of the river channel. From spring to autumn, adult H. perryi selected limnologically complex habitats with meandering channels. From summer to autumn, individuals selected habitats with more riparian forest cover. The inverse relationship between H. perryi detection and riparian forest area in spring was a result of seasonal defoliation in deciduous riparian forests.
  • Kentaro Honda, Takaomi Arai, Nobuyuki Takahashi, Kazushi Miyashita
    ICHTHYOLOGICAL RESEARCH 57 (4) 416 - 421 1341-8998 2010/11 [Refereed][Not invited]
    Microchemical analysis of the strontium (Sr) and calcium (Ca) ratios of otoliths was conducted to determine the life history and migration of anadromous Sakhalin taimen, Hucho perryi. In 2008 and 2009, 10 specimens were sampled from Lake Akkeshi in eastern Hokkaido, Japan. Our results indicated that some specimens migrated to brackish waters during their early life histories. Because the Sr:Ca ratios of the specimens in this study were all less than those of specimens from Sakhalin Island during a previous study, specimens from Lake Akkeshi may have migrated to brackish water, or may have remained in the ocean for only a short period.
  • Kenji Minami, Hiroki Yasuma, Naoki Tojo, Shin-ichi Fukui, Yusuke Ito, Takahiro Nobetsu, Kazushi Miyashita
    FISHERIES SCIENCE 76 (5) 729 - 736 0919-9268 2010/09 [Refereed][Not invited]
    Sustainable management of the kelp forests of the Shiretoko Peninsula, a World Natural Heritage site, is necessary due to kelp's ecological and economic importance. The objectives of this study were to estimate the area of kelp forests and to clarify their spatial characteristics in coastal waters of the Shiretoko Peninsula. Data on the presence/absence and thickness of kelp forests were collected via acoustic observation on transects over about 80 km using an echosounder at 200 kHz. Acoustic data were geostatistically interpolated, and the areas covered by kelp forests were estimated. Differences in kelp distribution between the eastern and western sides of the peninsula were compared. The total area of kelp forest was 3.88 km(2) (eastern area: 3.49 km(2); western area: 0.39 km(2)). The range of thickness of the kelp forests was 34-91 cm. Many kelp forests in the eastern area were thick (>78 cm) and distributed continuously, while kelp forests in the western area were sparsely distributed.
  • Ko Fujioka, Ryo Kawabe, Alistair J. Hobday, Yoshimi Takao, Kazushi Miyashita, Osamu Sakai, Tomoyuki Itoh
    FISHERIES SCIENCE 76 (3) 403 - 410 0919-9268 2010/05 [Refereed][Not invited]
    Acoustic tags were used to examine the spatial and temporal distribution of southern bluefin tuna (SBT) in southern Western Australia, which is in a region where fishery-independent acoustic surveys of the recruitment abundance index of SBT have been historically undertaken. We investigated patterns of SBT distribution within and inshore of the acoustic survey area during three summer seasons. Annual differences in distribution patterns were characterized by two distinctive migration pathways. An inshore-migrating pathway was observed in two seasons (2004/2005 and 2006/2007), with a relatively high proportion of tagged SBT (84.5, 65.0%) migrating inshore of the acoustic survey area. The other pathway was concentrated along the shelf (2005/2006 season), with an estimated 63.3% of tagged SBT moving within the survey area. These variable migration patterns may bias the interannual fluctuations in abundance indices. Current survey methods can be modified to include both inshore and continental shelf areas. This contribution shows that the accuracy of acoustic surveys can be improved by including ecological patterns.
  • Hiroki Yasuma, Kouichi Sawada, Yoshimi Takao, Kazushi Miyashita, Ichiro Aoki
    ICES JOURNAL OF MARINE SCIENCE 67 (1) 135 - 144 1054-3139 2010/01 [Refereed][Not invited]
    Yasuma, H., Sawada, K., Takao, Y., Miyashita, K., and Aoki, I. 2010. Swimbladder condition and target strength of myctophid fish in the temperate zone of the Northwest Pacific. - ICES Journal of Marine Science, 67: 135-144.
  • Kenji Minami, Akira Hamano, Takeshi Nakamura, Yoshimi Takao, Hiroki Yasuma, Kazushi Miyashita
    Journal of the Marine Acoustics Society of Japan The Marine Acoustics Society of Japan 37 (3) 147 - 155 0916-5835 2010 [Refereed][Not invited]
    The size of vesicles and amount of gas they contain is a major factor in the acoustic scattering of Sargassum plants. Here we investigate the morphological character of the vesicles and gas, and their theoretical and experimental target strength (TS) for two Sargassum species, Sargassum macrocarpum and S. siliquastrum. Both species are abundant in the coastal waters of Japan. A total of 593 vesicles were measured using a soft X-ray system, and their gas shapes were applied to two theoretical TS models (non-resonance and resonance). Experimental TS were obtained at 70 and 200 kHz using quantitative echo sounders in a freshwater tank. Gas fields were found in 418 vesicles, and the gas radius and external size of the vesicles were linearly related in both species. The theoretical TS of the non-resonance model was similar to the experimental TS of large vesicles (≥4.1 mm at 70 kHz, ≥2.8 mm at 200 kHz), whereas the theoretical TS of the resonance model was similar to the experimental TS of small vesicles (≤3.1 mm at 70 kHz, ≤1.9 mm at 200 kHz). Finally, we estimated TS-size equations according to the gas-size relationships and compared the results.
  • Kentaro Honda, Alistair J. Hobday, Ryo Kawabe, Naoki Tojo, Ko Fujioka, Yoshimi Takao, Kazushi Miyashita
    FISHERIES OCEANOGRAPHY 19 (2) 151 - 158 1054-6006 2010 [Refereed][Not invited]
    Juvenile southern bluefin tuna (Thunnus maccoyii, SBT) were monitored in nearshore waters off southwest Australia using acoustic tagging and monitoring over five austral summers (2002/2003-2006/2007) to determine patterns in age-based distribution of SBT. A total of 20-70 receivers were deployed in early December along one to three cross-shelf transects and at three inshore topographic features (lumps) where SBT are known to occur; and a total of 59-84 juvenile SBT (41-90 cm fork length) were tagged and released each year. After several months, receivers were recovered, and data extracted. In 2002/2003 and 2003/2004, 2-yr-old SBT were detected more frequently in nearshore areas than did 1-yr old fish. Similarly in 2004/2005 and 2006/2007, it was the larger 1-yr-old SBT that were detected more frequently at inshore lumps (> 85% of detections) while small 1-yr-old SBT were detected more widely over the study area. In 2005/2006, although large 1-yr-old SBT were still detected more frequently at inshore lumps than small 1-yr old SBT, the percentage of all detections at lumps was lower at 31.5%, indicating wider distribution of both small and large age-1 fish. The observed age-dependent distribution pattern may be enhanced by the distribution of prey, which disperse or concentrate depending on the local oceanography.
  • Hiroki Yasuma, Tatsuki Ohshima, Satoshi Honda, Kazushi Miyashita, Ichiro Aoki
    Nippon Suisan Gakkaishi (Japanese Edition) 76 (3) 362 - 369 0021-5392 2010 [Refereed][Not invited]
    California headlightfish Diaphus theta is the most abundant mesopelagic fish in the subarctic Pacific. Day- and nighttime field acoustic data and biological samples were obtained in January 2000, in the Pacific area off eastern Hokkaido to estimate fish density and total biomass of D. theta. Sound scattering layers composed mainly of immature D. theta (63 mm length on average) were widely distributed around the shelf edge (> 300 m water depth). Relatively dense schools were observed below the depth of 250 m during the daytime, although the schools were scattered widely above 50 m depth during the nighttime. Fish density was estimated to be 17.3 g/m2 on average, which was more than several times higher than that estimated by conventional methods such as net sampling gears. Total biomass in the survey area (2,083 km2) was estimated to be about 35,900 t.
  • Ko Fujioka, Alistair J. Hobday, Ryo Kawabe, Kazushi Miyashita, Kentaro Honda, Tomoyuki Itoh, Yoshimi Takao
    FISHERIES OCEANOGRAPHY 19 (3) 183 - 195 1054-6006 2010 [Refereed][Not invited]
    The spatial habitat utilization of juvenile southern bluefin tuna in southern Western Australia was investigated using automated acoustic receivers with acoustic transmitters implanted in tagged fish during three austral summers (2004/2005, N = 79 fish, 2005/2006, N = 81, 2006/2007, N = 84). Seventy acoustic receivers were deployed at three cross-shelf lines and three coastal topographic features (lumps) between December and May. We observed markedly different patterns of habitat utilization between the three seasons: (i) aggregation at lumps in 2004/2005 and 2006/2007, and (ii) wide distribution over the continental shelf (i.e., few occurring at lumps) in 2005/2006. Vertical profile by conductivity-temperature-depth casts showed these spatial shifts were caused by interannual changes in the presence of sub-Antarctic water. The sub-Antarctic water was present in the subsurface layer close to the continental slope only during 2005/2006, and the area had higher chlorophyll-a concentrations than the coastal areas, including at the lumps. These environmental characters, related to the nutrient rich sub-Antarctic water, appear to have a strong influence on fish distributions in 2005/2006, and may occur generally during La Nina events. Interannual fluctuations in habitat utilization will influence detection of fish in recruitment monitoring surveys and thus bias the resulting juvenile abundance indices.
  • Spatial analysis of Isada Krill (Euphausia pacifica) distribution in frontal environments in the North Pacific Ocean
    Naoki Tojo, Ryuichi Matsukura, Hiroki Yasuma, Shiroh Yonezaki, Hikaru Watanabe, Shigeyuki Kawahara, Hiroto Murase, Kazushi Miyashita
    GIS/Spatial Analyses in Fishery and Aquatic Sciences 4 115 - 138 2010 [Refereed][Not invited]
  • Ryuichi Matsukura, Hiroki Yasuma, Hiroto Murase, Shiroh Yonezaki, Tetsuichiro Funamoto, Satoshi Honda, Kazushi Miyashita
    FISHERIES SCIENCE 75 (6) 1377 - 1387 0919-9268 2009/11 [Refereed][Not invited]
    The mass density and sound-speed contrasts against surrounding seawater (g and h, respectively) of Neocalanus copepods (N. cristatus and N. plumchrus) were measured in 2006 and 2007 to compute the theoretical target strength (TS). The values of g ranged from 0.997 to 1.009 in N. cristatus and from 0.995 to 1.009 in N. plumchrus. There were no correlations between prosome length (PL) and g. The values of h ranged from 1.006 to 1.021 in N. cristatus and from 1.013 to 1.025 in N. plumchrus and varied with changes in temperature. TS was estimated with the theoretical sound scattering model using the values of g and h based on the temperature, salinity, and depth of the location where the specimens were collected. Regressions of the tilt-averaged TS versus PL were obtained at 38, 120, and 200 kHz. The averaged TS of N. cristatus and N. plumchrus at 120 kHz, which is widely used as a high frequency, ranged from -110.0 to -103.1 dB and from -121.4 to -109.7 dB, respectively. There was a positive correlation between frequency and averaged TS: the higher the frequency, the higher the value of averaged TS. The TS at 120 and 38 kHz varied from 14.8 to 16.4 dB in N. cristatus and from 17.9 to 18.7 dB in N. plumchrus, respectively; that at 200 and 120 kHz varied from 2.9 to 5.5 dB in N. cristatus and from 5.3 to 6.5 dB in N. plumchrus, respectively.
  • Hiroki Yasuma, Ryo Nakagawa, Takashi Yamakawa, Kazushi Miyashita, Ichiro Aoki
    FISHERIES SCIENCE 75 (3) 545 - 552 0919-9268 2009/05 [Refereed][Not invited]
    Sound-speed and density contrasts (h and g, respectively), important acoustic material properties, of Japanese sandeel Ammodytes personatus were measured to estimate theoretical target strength (TS). The measured sound-speed contrast of adult fish varied between 1.016 and 1.023 (mean 1.020), and showed temperature dependence. The measured density contrast differed significantly between juvenile and adult. The density contrast of juvenile varied between 1.017 and 1.024 (1.021), and that of adult varied between 1.026 and 1.038 (1.032). Using these results, TS at 38 and 120 kHz in the fishing season were estimated by an empirical sound scattering model. TS of an individual fish varied significantly with change of tilt angle. TS of near-dorsal aspect (TS(max)) and tilt-averaged TS (TS(ave)) differed by up to 7 dB. At both frequencies, two different TS(ave)-length relationships (TS(ave) = a log L + b) were obtained for adult and juvenile. The coefficients of log L of adult were close to 20, suggesting that backscattering strength was proportional to square of body length. These values were larger in juvenile (34.0 at 120 kHz, 56.5 at 38 kHz), suggesting that backscattering strength varied drastically with the cube or fifth power of body length.
  • Makoto Aruga, Yuichi Tsuda, Ko Fujioka, Kentaro Honda, Yasushi Mitsunaga, Kouji Mihara, Kazushi Miyashita
    Ecology and Civil Engineering 12 (2) 119 - 130 1882-5974 2009 [Refereed][Not invited]
    We tracked eight matured chum salmons (Oncorhynchus keta) using acoustic and radio telemetry to understand their upriver migration around ca. 120 to 180 km site starting from the mouth of the Ishikari River in autumn 2002-2004. This study area was divided into the natural levee area, the gorge area, and the basin area including the past major spawning sites until ca. 1940s. Three tagged fish reached to the basin area, and two fish reached to the natural levee area. The maximum duration of the upstream migration was 17 days, and the maximum migration distance was 56 km. Mean migration speed in the basin area was 6.6 km/day, where the staying behavior was frequently observed, was approximately three times slower than those of the natural levee area (19.5 km/day) and the gorge area (14.8 km/day). The basin area had better conditions of substrates, depth, flow velocity and subsurface flows for O. Keta spawning than the other areas. In addition, groundwater upwelling for egg survival and hatching occurs adequately in the basin area. Their migration patterns reflected geographical differences among three areas. Therefore, the observed slower migration in the basin area was probably due to their pre-spawning behaviors including searching for spawning sites and mates. The faster migration in the natural levee area and gorge areas was due to utilization of these areas as corridors. © 2009, Ecology and Civil Engineering Society. All rights reserved.
  • Alistair J. Hobday, Ryo Kawabe, Yoshimi Takao, Kazushi Miyashita, Tomoyuki Itoh
    TAGGING AND TRACKING OF MARINE ANIMALS WITH ELECTRONIC DEVICES 9 405 - + 1571-3075 2009 [Refereed][Not invited]
    Juvenile southern bluefin tuna (SBT, Thunnus maccoyii), migrate down the coast of Western Australia reaching the southern coast at age-1. In these waters an acoustic survey for SBT schools was initiated to generate a fisheries-independent abundance index. A decline in this abundance index led to an acoustic tagging and monitoring project to determine if a change in migration route or timing could explain the decline. Five years of acoustic monitoring revealed interannual differences in key factors that could impact the abundance index. Acoustic tag data were used to demonstrate that (i) a high proportion of fish (similar to 70%) may be too shallow for detection in the acoustic survey, and that interannual variation in (ii) inshore-offshore fraction (similar to 30-70% each year) and (iii) residence time (12-37 days) will impact calculation of an index. These factors should be included in estimating an abundance index for SBT, together with a correction for (iv) the fraction of juvenile SBT that migrate to southern Western Australia. Collectively, these results illustrate how electronic tagging data can be used to improve understanding of abundance patterns necessary for sustainable management of this exploited species.
  • 本多健太郎, 野田裕二, 津田裕一, 宮下和士
    日本生態学会誌 29 239 - 247 2009 [Refereed][Not invited]
  • Hiroto Murase, Morio Ichihara, Hikaru Watanabe, Shiroh Yonezaki, Shigeyuki Kawahara, Kazushi Miyashita
    Fisheries Oceanography (386) 401  2009 [Refereed][Not invited]
  • Target strength of Maurolicus japonicus at 38 kHz and 120 kHz.
    Tadanori Fujino, Kazuhiro Sadayasu, Koki Abe, Hideaki Kidokoro, Hiroki Yasuma, Kazushi Miyashita
    Journal of the Marine Acoustics Society of Japan 36 241 - 249 2009 [Refereed][Not invited]
  • Hiroto Murase, Morio Ichihara, Hiroki Yasuma, Hikaru Watanabe, Shiroh Yonezaki, Hiroshi Nagashima, Shigeyuki Kawahara, Kazushi Miyashita
    FISHERIES OCEANOGRAPHY 18 (6) 386 - 401 1054-6006 2009 [Refereed][Not invited]
    The acoustic characteristics of biological backscattering in the western North Pacific were studied to verify expert knowledge on species composition in the echosigns. The survey was conducted in the Kuroshio-Oyashio inter-frontal zone and the subarctic waters in April 2003. The species composition of backscatterings was identified by using midwater trawl, Isaacs-Kidd midwater trawl and Bongo net. The differences of mean volume backscattering strengths between 120 and 38 kHz (Delta MVBS(120-38)) were calculated for the backscatterings. Six types of backscatterings were classified based on the results of net samples and the Delta MVBS(120-38). The Delta MVBS(120-38) of each group was as follows: copepods 13.7-17.3 dB, krill 11.6-15.3 dB, Japanese anchovy -1.6 to 1.1 dB, a myctophid, Diaphus theta-0.8 dB, sand lance 6.1 dB and larvae and juveniles of pelagic and mesopelagic fish -9.6 to -4.0 dB. The results suggest that biological backscatterings in the Kuroshio-Oyashio inter-frontal zone and subarctic waters of the western North Pacific in spring can be characterized by using Delta MVBS.
  • Honda Kentaro, Noda Yuji, Tsuda Yuichi, Yasuma Hiroki, Miyashita Kazushi
    JAPANESE JOURNAL OF ECOLOGY 日本生態学会暫定事務局 59 (3) 239 - 247 0021-5007 2009 [Refereed][Not invited]
    At present, the distribution of endangered Sakhalin taimen, <i>Hucho perryi</i>, in Japan is limited to several rivers and lakes in Hokkaido. Although field studies of adult H. perryi have focused on spawning habits, other ecological information is lacking. Here, we report on field research conducted to elucidate the seasonal migration patterns of adult H. perryi in the Bekanbe-ushi River system in Hokkaido using acoustic telemetry. From early May to late November 2007, we tracked five taimen with acoustic tags using 13 acoustic receivers. We detected the tagged fish a combined total of 37,683 times. The fish migrated an average of 33.4±12.5 (SD) km downstream from their spawning area over 1-4 days. They primarily resided mid-downstream in the spring, upper-downstream in the summer, and downstream in the autumn. Logistic regression analysis revealed that the upward migration by tagged fish living downstream was affected by ambient daily maximum water temperatures in the summer, whereas spring and autumn downward migrations were facilitated by ambient daily minimum water temperatures in mid-stream areas. These results suggest that the seasonal migration patterns of adult H. perryi are closely associated with the water temperature regimes of this river system.
  • Osamu Shida, Hiroya Miyake, Tomonori Kaneta, Dryotaro Ishida, Kazushi Miyashita
    Nippon Suisan Gakkaishi (Japanese Edition) 74 (2) 152 - 160 0021-5392 2008/03 [Refereed][Not invited]
    To understand winter distribution patterns of young walleye pollock Theragra chalcogramma and its determinants, we conducted an echo integration survey on the Pacific coast of eastern Hokkaido (the Doto area) in late February of 1998. Pollock aggregations were mainly located from the shelf edge to the continental slope region (150-400 m) with temperature ranging from 2 to 4°C. In contrast, the fish echoes were not present in the continental shelf region, which was dominated by the low temperature (< 2°C) and low salinity (< 33.0) Coastal Oyashio Water. Walleye pollock showed diel vertical migration patterns, involving staying near the bottom during the day and rising to the mid-water area at night. Our results show the fish's (1) offshore-ward movements and (2) concentrations in deeper water in winter. These observed pollock distribution changes were probably enhanced in marine environmental dynamics, caused by intrusion of the Coastal Oyashio Water into the shelf region. It is suggested that such distribution changes affect young pollock survival and are important for determining year class strength.
  • 永島宏, 村瀬弘人, 米崎史郎, 松倉隆一, 南憲吏, 永木利幸, 川原重幸, 宮下和士
    Miyagi Prefectural report of fisheries science 宮城県水産研究開発センター 8 (8) 15 - 25 1346-4329 2008 [Not refereed][Not invited]
  • 太平洋西部におけるツノナシオキアミ(Euphausia pacifica)の分布特性の定量的空間解析
    東条斉興, 清水大介, 安間洋樹, 川原重幸, 渡辺光, 米崎史郎, 村瀬弘人, 宮下和士
    水産海洋研究 72 165 - 173 2008 [Refereed][Not invited]
  • 安間 洋樹, 澤田 浩一, 宮下 和士, 青木 一郎
    The Journal of the Marine Acoustics Society of Japan 海洋音響学会 35 (1) 17 - 28 0916-5835 2008 [Refereed][Not invited]
  • Osamu Shida, Tomonori Hamatsu, Akira Nishimura, Akifumi Suzaki, Jun Yamamoto, Kazushi Miyashita, Yasunori Sakurai
    DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY 54 (23-26) 2822 - 2831 0967-0645 2007 [Refereed][Not invited]
    The Japanese Pacific walleye pollock (Theragra chalcogramma) stock is the largest stock of this species in Japanese waters. It is a key component of the Oyashio ecosystem. In southern Hokkaido waters, these fish spawn mainly during January and February near the mouth of Funka Bay (FB), and most eggs and larvae are transported into FB. During midsummer juvenile pollock migrate along the southern coast of Hokkaido to a nursery ground on the continental shelf off eastern Hokkaido (Doto area). However, some eggs and larvae are transported southward to the Tohoku region (TR). Transport depends largely on the Oyashio. which generally flows southward along the eastern coasts of Hokkaido and Tohoku. Thus, this stock has two different recruitment routes: FB-Doto and FB-TR. In the 1980s, when the southward flow of the Oyashio was strong, the number of age-2 pollock estimated from a virtual population analysis (VPA) indicated that recruitment to the entire stock remained at a medium level. In the 1990s, when the Oyashio weakened, strong year-classes occurred in 1991. 1994, and 1995, but not in the latter half of the 1990s. Juvenile catches in the TR by commercial fisheries, which can be taken as indices of recruitment level via FB-TR, were high during the 1980s and decreased in the 1990s. Although there was no significant difference in the average number of recruits between the 1980s and the 1990s as estimated from a VPA, the recruitment patterns differed between the two decades. Here, we propose that recruitment routes of this stock shifted in response to environmental changes. (C) 2007 Elsevier Ltd. All rights reserved.
  • Atsumu Watanabe, Kazushi Miyashita, Ryuich Matsukura, Saho Morioka, Yoshihiro Ikewaki, Keisuke Mori
    GIS/Spatial Analyses in Fishery and Aquatic Sciences 3 347 - 359 2007 [Refereed][Not invited]
  • H Yasuma, Y Takao, K Sawada, K Miyashita, Aoki, I
    ICES JOURNAL OF MARINE SCIENCE 63 (4) 683 - 692 1054-3139 2006/05 [Refereed][Not invited]
    This paper reports theoretical values of target strength (TS) for the lanternfish Stenobrachius leucopsarus, a fish without an airbladder, which dominates the Subarctic marine mesopelagic fish community. Two models for liquid-like slender bodies, the general prolate-spheroid model (PSM) and the deformed-cylinder model (DCM), were used to compute the TS of the fish relative to its orientation. The relative mass density g and the sound speed h in sea-water were measured and used in both models. To confirm the appropriateness of the models, tethered experimental measurements were carried out at 38 kHz for five specimens. The value of g measured by the density-bottle method was very low (1.002-1.009) compared with that of marine fish in general. The value of h measured by the time-average approach was 1.032-1.039 at the water temperature at which S. leucopsarus is found. TS-fluctuation patterns against fish orientation (the TS pattern) estimated from the DCM and PSM were in good agreement in the area of their main lobes. Both models reproduced the main lobes of the measured TS patterns in near-horizontal orientation (<+/- 20 degrees), and they were considered to be effective in measuring the TS of S. leucopsarus in a horizontal (swimming) position. After these comparative experiments, we computed the TS of 57 fish (27.8-106.9 mm) at 38, 70,120, and 200 kHz, using the DCM. A plot of body length (in log scale) against TS showed a non-linear relationship at all frequencies. S. leucopsarus had a very low TS (<-85 dB, TScm), suggesting that acoustic assessment would be highly sensitive, especially when the proportion of small fish is high (e.g. L/lambda < 2), and an appropriate frequency should be considered that takes into account both the length composition and the depth of occurrence. (c) 2006 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All fights reserved.
  • 鈴木勝也, 高木力, 宮下和士
    数理水産科学 数理水産科学研究会 4 23 - 28 1348-6802 2006 [Refereed][Not invited]
  • S Torisawa, K Miyashita, R Kawabe, Y Fujimori, T Oshima, S Honda, K Sato
    FISHERIES RESEARCH 77 (1) 4 - 9 0165-7836 2006/01 [Refereed][Not invited]
    Although visual information can help to monitor fish behavior in situ, quantitative analysis from images is difficult. There is little quantitative information from images on fish behavior in situ. In this study, we used digital still-picture loggers (DSLs) to monitor the bearing and tilt angles of walleye pollock, Theragra chalcogramma, in a trawl in situ. We attached two DSLs to a trawl net and recorded still pictures of fish near the mouth of the trawl. Eleven pictures of walleye pollock were obtained during 79 trawl surveys. From the still images, we calculated the bearing and tilt angles of the fish using the ratio of body length and body height. We confirmed the accuracy of the calculated angles by comparing the computed angles using image-processing software. The calculated angles agreed with the angles computed using the software. Therefore, our simple method can be used to monitor fish bearing and tilt angles in situ. Based on our results, bearing angles of walleye pollock were not shown in the same direction to a trawl. Furthermore, the fish tilt angles differed significantly between adults and juveniles. (C) 2005 Elsevier B.V. All rights reserved.
  • Tadanori Fujino, Kazushi Miyashita, Ichiro Aoki, Shinya Masuda, Ryousuke Uji, Tsuyoshi Shimura
    Nippon Suisan Gakkaishi (Japanese Edition) 71 (6) 947 - 956 0021-5392 2005/11 [Refereed][Not invited]
    We examined threshold-setting methods to identify Maurolicus japonicus SL (Scattering Layer) in the Sea of Japan. Acoustic survey data were collected in several months (May, June, Aug., Sep., and Oct.) from 2000 to 2003 around the Oki Islands, southwest of the Sea of Japan. The results showed the following threshold-setting method to be appropriate: to set the value as the lower limit SV threshold obtained by subtracting 10 dB from the averaged maximum SV of the water column. The depth range extracted by this method matched the existence of M. japonicus confirmed by the bottom and midwater trawl sampling. This method corresponds to the change of packing density by seeking the threshold baseline from the M. japonicus SL.
  • T Fujino, K Miyashita, Aoki, I, S Masuda, R Uji, T Shimura
    NIPPON SUISAN GAKKAISHI 71 (6) 947 - 956 0021-5392 2005/11 [Refereed][Not invited]
    We examined threshold-setting methods to identify Maurolicus japonicus SL (Scattering Layer) in the Sea of Japan. Acoustic survey data were collected in several months (May, June, Aug., Sep., and Oct.) from 2000 to 2003 around the Oki Islands, southwest of the Sea of Japan. The results showed the following threshold-setting method to be appropriate: to set the value as the lower limit S-v threshold obtained by subtracting 10 dB from the averaged maximum S-v of the water column. The depth range extracted by this method matched the existence of M. japonicus confirmed by the bottom and midwater trawl sampling. This method corresponds to the change of packing density by seeking the threshold baseline from the M japonicus SL.
  • Y Fujimori, K Chiba, T Oshima, K Miyashita, S Honda
    FISHERIES SCIENCE 71 (4) 738 - 747 0919-9268 2005/08 [Refereed][Not invited]
    Variations in trawl dimension, bottom contact, and catch with differing warp lengths during walleye pollock surveys conducted by the Fisheries Research Agency were examined. The ratio of warp length to fishing depth (scope ratio) was set at 2.5, 3.0 and 3.5 at depths of 110 m. At a 2.5 scope ratio, the net mouth shape and footgear contact fluctuated, as the trawl door did not contact the bottom. Footgear contact was complete when the scope ratio was 3.0 or more. Walleye pollock, sculpins and flatfishes were the main catch in all tows, and the catch increased with scope ratio. There was no difference in the length frequency of walleye pollock (n = 300) captured at 2.5 and 3.0 scope ratio. However, the length frequency at 3.5 was significantly different from that of other scope ratios. These results suggest that at a scope ratio of 3.0 or more, the trawl door will not leave the bottom at any depths. To compliment echo surveys for walleye pollock, a 3.0 scope ratio would be optimal, since the catch data for a 3.5 scope ratio was dissimilar from that of scope ratios.
  • 魚群行動における視覚と側線感覚機能の数理モデルによる評価
    鈴木勝也, 高木力, 鳥澤眞介, 福田漠生, 村田修, 山本眞司, 宮下和士
    数理水産科学 3 37 - 42 2005 [Refereed][Not invited]
  • K Miyashita, K Tetsumura, S Honda, T Oshima, R Kawabe, K Sasaki
    FISHERIES OCEANOGRAPHY 13 (Suppl. 1) 99 - 110 1054-6006 2004/12 [Refereed][Not invited]
    In this study, we tried to accurately discriminate between zooplankton and walleye pollock using a quantitative echosounder at two frequencies (38 and 120 kHz). To estimate the abundance of walleye pollock and zooplankton (mainly Euphausia pacifica), an acoustic and trawling survey with bongo net sampling and CTD (X-CTD) was conducted during June 2001 off the Pacific coast of eastern Hokkaido, Japan. Neocalanus copepods and E. pacifica were predominant in almost all the net samples. One Size class of Neocalanus copepods (mean TL +/- SD = 2.0 +/- 1.1 mm, N = 1 044 080) and two size classes of E. pacifica (mean TL +/- SD = 6.1 +/- 2.2 mm, N = 13,099; mean TL +/- SD = 15.4 +/- 3.6 mm, N = 7628) were collected. The distribution patterns of these two classes and of walleye pollock were identified using the volume back scattering strength (Sv) difference method. On the continental shelf, the walleye pollock schools (small walleye pollock: mainly age 1 and 2) overlapped with almost all zooplankton layers during both day (near the sea bottom and mid-water) and night (mid-water and sea surface). Near and offshore of the continental shelf break, during day, the walleye pollock schools (large walleye pollock: mainly older than age 3) overlapped with almost all zooplankton layers near the sea bottom, but during night, the large walleye pollock schools (which were mainly distributed near the sea bottom) showed little overlap with most zooplankton layers (which were mainly distributed between mid-water and sea surface). This result suggests differences in feeding strategies between small and large walleye.
  • D Kang, K Sadayasu, S Mukai, K Iida, D Hwang, K Sawada, K Miyashita
    FISHERIES SCIENCE 70 (5) 819 - 828 0919-9268 2004/10 [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.
  • R Kawabe, Y Naito, K Sato, K Miyashita, N Yamashita
    ICES JOURNAL OF MARINE SCIENCE 61 (7) 1080 - 1087 1054-3139 2004/10 [Refereed][Not invited]
    It is well known that flatfish species such as plaice can utilize the selective tidal stream to conduct vertical movements. However, detailed description of actual swimming behaviour is lacking, principally as a result of the difficulties encountered in monitoring the behaviour of flatfish in the open sea. The present study describes the use of a newly developed data-logger in obtaining simultaneous recordings of the swimming speed, depth, tailbeat, and body angle of free-ranging Japanese flounder (Paralichthys olivaceus) in the open sea. Our data indicate that Japanese flounders adopt a tailbeat-and-glide behaviour. They are found to glide downward without tailbeats for propulsion, and only during the ascent phase are tailbeats conducted. Flounders move horizontally at speeds of 0.59-1.23 km d(-1) and at a maximum speed of 0.70-0.82 km h(-1) in the open sea. Modal flounder swimming speeds are 30-40cms(-1) (0.57-0.76 and 0.58-0.77BLs(-1)), i.e. sometimes lower than the threshold of the speed sensor. In most cases, however, tailbeat oscillations occur at frequencies of 1.2-1.4 Hz. Moreover, flounders travel at a significantly steeper angle during the ascent phase than during the descent phase. In both cases it is believed that flounder optimize the energetic costs of migration, as has been shown for tuna, sharks, and seals. (C) 2004 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
  • 異なる光環境下における魚群の行動特性について
    鈴木勝也, 髙木 力, 鳥澤眞介, 宮下和士
    数理水産科学 2 37 - 42 2004 [Not refereed][Not invited]
  • 鈴木 勝也, 高木 力, 宮下 和士
    日本水産工学会学術講演会講演論文集 16 195 - 196 0917-3943 2004 [Not refereed][Not invited]
  • K Miyashita
    ICES JOURNAL OF MARINE SCIENCE 60 (3) 532 - 537 1054-3139 2003/06 [Refereed][Not invited]
    Diurnal changes in the acoustic-frequency characteristics of "shirasu", a post-larval stage of Japanese anchovy (Engraulis japonicus), were analysed based on theoretical scattering models. Since post-larval swimbladders contain gas at night but not during the day, the distorted-wave Born approximation (DWBA), based on the deformed-cylinder model, which assumes there is no gas in the swimbladder, was applied to daytime observations, and the fish-bladder resonance model, which assumes there is gas in the swimbladder, to those taken at night. The two sets of acoustic frequencies employed were 50 and 200 kHz, which are those used for shirasu commercial fishing, and 38 and 120kHz, which are usually employed for acoustic surveys using a quantitative echosounder. During the daytime, differences in shirasu target strengths between the two frequencies were large, especially between 38 and 120 kHz, but at night there was little difference with frequency, suggesting that acoustic surveys for identifying and estimating the abundance of shirasu should be done during daytime, when differences occur between frequencies and the shirasu form dense schools. (C) 2003 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.
  • H Yasuma, K Sawada, T Olishima, K Miyashita, Aoki, I
    ICES JOURNAL OF MARINE SCIENCE 60 (3) 584 - 591 1054-3139 2003/06 [Refereed][Not invited]
    This article reports theoretical values of target strength (TS) for mesopelagic lanternfishes based on morphological measurements of their swimbladders. Three species of lanternfishes, Diaphus theta (26.9-77.4 mm standard length (SL)), Symbolophorus californiensis (85.0-108.4 mm SL), and Notoscopelus japonicus (126.0-133.2 mm SL), were examined. After external morphological measurement of the fish body, a specialized "soft X-ray" imaging system was used to map the swimbladders and obtain their morphological parameters. The swimbladder was inflated in D. theta, uninflated in S. californiensis, and was absent in N. japonicus. For D. theta, the swimbladder length does not increase in proportion to the body length, suggesting that the contribution of the swimbladder to acoustic reflection is reduced with growth in this fish. Based on the morphological measurements, the theoretical TS of the fish at 3 8 kHz was calculated using the approximate deformed-cylinder model (DCM) and the general prolate-spheroid model (PSM). For all three species, the calculations showed about 3 dB difference between the TS indicated by the DCM and PSM. Given that the description of body shape is poor in PSM, the DCM results were adopted for fish without a swimbladder or an empty one. The intercept b(20) in the standard formula TS = 20 log SL + b(20) was -85.7 dB (DCM) for S. californiensis and -86.7 dB (DCM) for N. japonicus. On the other hand, the PSM model was adopted for D. theta since its swimbladder has too small an aspect ratio to apply the DCM. For D. theta, the relationship between SL and TS is best expressed by TS = 11.8 log SL - 63.5, which implies that its scattering cross-section is not proportional to the square of the body length. (C) 2003 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.
  • 閉鎖空間内における魚群行動の確率モデル
    鈴木勝也, 髙木力, 守冨裕, 鳥澤眞介, 宮下和士
    数理水産科学 1 15 - 20 2003 [Not refereed][Not invited]
  • Hiroki Yasuma, Tatsuki Ohshima, Kouichi Sawada, Kazushi Miyashita, Ichiro Aoki
    ICES Journal of Marine Science 60 585 - 592 2003 [Refereed][Not invited]
  • J Yamamoto, S Masuda, K Miyashita, R Uji, Y Sakurai
    BULLETIN OF MARINE SCIENCE 71 (2) 987 - 992 0007-4977 2002/09 [Refereed][Not invited]
    The MOCNESS (Multiple Opening Closing Net and Environmental Sampling System) was used to investigate the distribution of the early life stages of the Japanese common squid Todarodes pacificus in the southwest Sea of Japan near the Oki Islands, a suspected spawning ground of this species. The largest catches of hatchling-sized paralarvae occurred at the surface layer (0-25 in), and paralarval mantle lengths increased with increasing sampling depth, suggesting that T pacificus paralarvae gradually descend in the water column life cycle as they grow. There was no clear difference in the horizontal distribution among the different size groups.
  • M Kang, M Furusawa, K Miyashita
    ICES JOURNAL OF MARINE SCIENCE 59 (4) 794 - 804 1054-3139 2002/08 [Refereed][Not invited]
    Acoustic species identification is very important for fisheries' operations and surveys. One of the most promising methods for identification is to utilize the difference of mean volume backscattering strengths (DeltaMVBS) among frequencies. Improvement of this technique is the aim of this study. The DeltaMVBS must be obtained for a common observation range among frequencies so that the difference can be attributed solely to frequency characteristics of the sound scattering of targets organisms. We derived the common observation range of at least up to 150 m for our quantitative echosounder operating at 38 and 120 kHz with the same beam widths of 8.5degrees. We related DeltaMVBS data obtained off northeastern Japan to specific marine organisms combined with the swimming depth and water temperature information. The echoes with small DeltaMVBS ( - 1 dB<DeltaMVBS<4 dB) were attributed to the walleye pollock (Theragra chalcogramma) and the echoes with large DeltaMVBS (> 10 dB) to krill (Euphausia pacifica). The changing pattern of DeltaMVBS suggested complicated behaviour between species such as predator and prey interaction. In order to obtain reliable and detailed information the integration cell should be small and the DeltaMVBS should be displayed as an echogram in an absolute colour scale. (C) 2002 Published by Elsevier Science Ltd on behalf of International Council for the Exploration of the Sea.
  • Yoo-Won Lee, Kazushi Miyashita, Tsutomu Nishida, Sei-ichiro Harada, Tohru Mukai, Kohji Iida
    Journal of Fisheries Science and Technology 5 (3) 206 - 211 2002 [Refereed][Not invited]
  • Kazushi Miyashita
    Nippon Suisan Gakkaishi (Japanese Edition) 68 (4) 564 - 568 0021-5392 2002 [Refereed][Not invited]
    The diurnal changes in the acoustic frequency characteristics of Japanese anchovy (Engraulis japonicus) larvae were analyzed based on theoretical scattering models. Larval swim bladders contain gas at night, but not during the day, so the straight cylinder model (no gas in a swim bladder) was used for daytime observations, and the fish bladder resonance model (full gas in a swim bladder) was used for night observations. The sets of acoustic frequencies used were 50 kHz and 200 kHz, which are those used for shirasu commercial fishing, and 38 kHz and 120 kHz, which are those commonly used for acoustic surveys using a quantitative echo sounder system. During daytime, differences in the target strength (TS) of the anchovy larvae between the two frequencies were large (especially between 38 kHz and 120 kHz), but at night, there were few differences between frequencies. These results suggest that acoustic surveys for identifying and estimating the abundance of Japanese anchovy larvae should be performed during the day rather than at night, since this is when differences occur between frequencies and when larvae form dense schools.
  • Identifying fish species around the Oki island using echogram analysis
    Tadanori Fujino, Ryousuke Uji, Kazushi Miyashita, Koutarou Tetsumura, Shinya Masuda, Jun Yamamoto
    Proceedings of the ACOUSTGEAR2000 1 89 - 97 2001 [Refereed][Not invited]
  • 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]
  • Acoustical measurement of the horizontal distribution of isada krill (Euphausia pacifica Hanssen) off the Sanriku coast
    Kazushi Miyashita, Koutarou Tetsumura, Kouji Kooka, Hiroki Yasuma
    Proceedings of the ACOUSTGEAR2000 1 190 - 193 2001 [Refereed][Not invited]
  • Development and evaluation of new software used in acoustic surveys to estimate the abundance of fishery resources
    Koutarou Tetsumura, Kazushi Miyashita
    Proceedings of the ACOUSTGEAR2000 1 74 - 79 2001 [Refereed][Not invited]
  • In situ TS measurements of live southern bluefin tuna (Thunnus maccoyii) in cages
    Kazushi Miyashita, Tsutomu Nishida, Sei-ichiro Harada
    Proceedings of the ACOUSTGEAR2000 1 45 - 47 2001 [Refereed][Not invited]
  • Acoustical survey for estimation of tuna abundance using the Omni scan sonar
    Tsutomu Nishida, Kazushi Miyashita
    Proceedings of the ACOUSTGEAR2000 1 98 - 107 2001 [Refereed][Not invited]
  • Accurate frequency difference of volume backscattering strength for fish species information
    Myoung-Hee Kang, Masahiko Furusawa, Kazushi Miyashita
    Proceedings of the ACOUSTGEAR2000 1 65 - 73 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]
  • Spatial dynamics of southern bluefin tuna (Thunnus maccoyii) recruitment
    Tsutomu Nishida, Vincent Lyne, Kazushi Miyashita, Kiyoshi Itho
    GIS/Spatial Analyses in Fishery and Aquatic Sciences 1 86 - 103 2001 [Refereed][Not invited]
  • Aoki, I, K Miyashita
    FISHERIES RESEARCH 49 (2) 155 - 164 0165-7836 2000/12 [Refereed][Not invited]
    A sampling survey for Japanese anchovy Engraulis japonicus larvae and juveniles was carried out using two types of sampling gear for capturing a wide size range of fish in the Kuroshio Extension and Kuroshio-Oyashio transition regions in August 1996. Anchovy larvae were found widely far offshore. Total lengths (TLs) of the fish ranged mostly from 6 to 40 mm, which corresponded to 5-50 days after their hatching in July. The number of anchovy collected varied with sampling sites, but it was not clear what factors accounted for the variation. While the mean lengths of larvae taken in the Kuroshio Extension area tended to be smaller offshore, those in the transition area significantly increased in size as the distance offshore increased, perhaps because larger larvae migrated northward into the transition region. The mean growth rate of otolith-aged larvae was 0.63 mm per day, which was similar to those previously reported in the coastal waters. The daily mortality coefficient, which was estimated based on age-frequency distribution converted from length-frequency distribution, ranged from 0.362 to 0.136 per day. The mortality rates decreased with growth, being lowest for larger larvae offshore. (C) 2000 Elsevier Science B.V. All rights reserved.
  • K Miyashita, Aoki, I
    MARINE ECOLOGY PROGRESS SERIES 180 105 - 109 0171-8630 1999 [Refereed][Not invited]
    Two methods for acoustic estimation of zooplankton abundance using the difference in volume back-scattering strength (SV) at 2 frequencies between 38 and 200 kHz were examined in a situation where the biological composition was simple. Method 1 used the SV difference, and Method 2 used both SV difference and body length data from net samples. The high-pass sphere model and straight cylinder model were applied depending on dominant target species: when they were relatively small, such as copepods, the high-pass sphere model was used, and when adult krill were dominant the straight cylinder model was used to take the swimming angle of the adult krill into consideration. Acoustic estimates were compared with net samples. Using the high-pass sphere model, Method 1 provided plausible estimates of zooplankton size and biomass, and Method 2 provided better biomass estimates. Furthermore, it was shown that by using the straight cylinder model and swimming angle distribution, Method 1 can be applied to obtain estimations. of the krill's size and biomass.
  • 「実験イケス内のミナミマグロThunnus maccoyii幼魚のターゲットストレングスの直接測定」
    宮下和士, 西田勤
    水産海洋研究 63 8 - 13 1999 [Refereed][Not invited]
  • Kazushi Miyashita, Ichiro Aoki, Tadashi Asami, Hideki Mori, Kenji Taki
    Journal of the Korean Society of Fisheries Resoureces 1 128 - 135 1998 [Refereed][Not invited]
  • K Miyashita, Aoki, I, K Seno, K Taki, T Ogishima
    FISHERIES OCEANOGRAPHY 6 (4) 266 - 271 1054-6006 1997/12 [Refereed][Not invited]
    In this study, the feasibility of identification and abundance estimation of isada krill, Euphausia pacifica, was examined using a two-frequency (38 and 120 kHz) method. The acoustic survey and midwater trawling were conducted off the Sanriku coast, northern part of Honshu, Japan. In one pattern, the SV difference between the two frequencies was large, and in the other, the SV difference was small. These results were interpreted by scattering models, and showed that discrimination between isada krill and walleye pollock was possible.
  • 「4周波計量魚群探知機を用いた動物プランクトのサイズ別密度推定の試み」
    宮下和士, 青木一郎, 稲垣正
    水産海洋研究 61 61 - 66 1997 [Refereed][Not invited]
  • K Miyashita, Aoki, I, T Inagaki
    ICES JOURNAL OF MARINE SCIENCE 53 (2) 303 - 308 1054-3139 1996/04 [Refereed][Not invited]
    The swimming angle of isada krill (Euphausia pacifica Hansen) was measured in a tank and the target strength (TS) values were calculated using a theoretical scattering model. The average swimming angle was 30.4 degrees (s.d.=19.9 degrees), which was about 15 degrees less than that reported for Antarctic krill (Euphausia superba). Parameters for the swimming angle distribution were substituted into the straight cylinder model and the corresponding TS values were determined. The mean TS values of 16.4 mm isada krill for hovering animals were lower than the maximum TS; differences were 7.8-5.0 dB, 14.8-8.6 dB, and 18.1-10.8 dB at 50, 120, and 200 kHz, respectively. These differences will lead to a 1/6-1/3, 1/30-1/7, and 1/65-1/12 proportional difference, respectively, in estimating abundances compared to estimates based on the maximum TS. Measurements carried out al higher frequencies are more influenced by swimming angle than those at lower frequencies. However, the TS is less at lower Frequencies and it is more difficult to filter out noise. Thus, medium frequencies are suggested as the best for krill surveys. Additionally, when conducting resource surveys by echosounding, it is necessary to assign the appropriate swimming angles for different targets. Swimming angles need to be investigated further under a variety of conditions.
  • K Miyashita, Aoki, I, T Inagaki
    FISHERIES SCIENCE 62 (2) 327 - 328 0919-9268 1996/04 [Refereed][Not invited]
  • 制御法を用いたツノナシオキアミEuphausia pacificaのターゲットストレングスの測定
    宮下和士, 青木一郎, 飯田浩二, 向井徹, 黄斗湊
    水産海洋研究 60 215 - 220 1996 [Refereed][Not invited]
  • Kazushi Miyashita, Ichiro Aoki, Tadashi Inagaki
    Nippon Suisan Gakkaishi (Japanese Edition) 62 (1) 68 - 72 0021-5392 1996 [Refereed][Not invited]
    We examined two methods for acoustical estimation of zooplankton abundance using the high-pass sphere model and two frequencies. Frequencies were 50 kHz and 200 kHz. In Method 1, the body length of the zooplankton, which is necessary to estimate the biomass density, was derived theoretically from the difference of volume back-scattering strength (SV) at two frequencies. In method 2, this information was obtained by actual net sampling. Method 1 was useful to estimate size and biomass approximately in the survey area. Method 2 was useful to estimate biomass closely when biological compositions were simple. Both methods can be applied to acoustic observations of macro zooplankton by common echo sounders mounted on research vessels.
  • K Miyashita, Aoki, I, T Inagaki
    NIPPON SUISAN GAKKAISHI 62 (1) 68 - 72 0021-5392 1996/01 [Refereed][Not invited]
    We examined two methods for acoustical estimation of zooplankton abundance using the high-pass sphere model and two frequencies. Frequencies were 50 kHz and 200 kHz. In Method 1, the body length of the zooplankton, which is necessary to estimate the biomass density, was derived theoretically from the difference of volume back-scattering strength (SV) at two frequencies. In method 2, this information was obtained by actual net sampling. Method 1 was useful to estimate size and biomass approximately in the survey area. Method 2 was useful to estimate bio-mass closely when biological compositions were simple. Both methods can be applied to acoustic observations of macro zooplankton by common echo sounders mounted on research vessels.
  • 音響推定におけるツノナシオキアミの遊泳姿勢に関する研究
    宮下和士, 青木一郎, 稲垣正
    水産海洋研究 59 235 - 240 1995 [Refereed][Not invited]

Books etc

  • Fish Population Dynamics, Monitoring, and Management
    MIYASHITA Kazushi (Joint workAcoustic survey)
    Springer 2018
  • スマート農業
    宮下和士 (Contributor音響計測などの多次元計測とその応用による水産業のスマート化)
    農林統計出版 2014
  • 水辺と人の環境学(上)
    宮下和士 (Contributorブラウントラウト・ニジマス.)
    朝倉書店 2013
  • フィールド科学への招待
    宮下和士 (Contributor海洋生物資源を可視化する)
    三共出版 2006


  • 知県鈴地区に係る査で得られるデータを用いた魚群の定量化及び小型船舶を用いた計量魚群探知機調査による魚群来遊量把握に関する委託事業報告書
    朱妍卉, 岩原由佳, 南憲吏, 宮下和士  平成30年度海洋水産資源開発事業報告書  165  -187  2021  [Not refereed]
  • 野田琢嗣, 小泉拓也, 藤岡紘, 北川貴士, 宮下和士  日本水産学会大会講演要旨集  2020-  2020
  • Development and application of acoustic methods for monitoring Fisheries resources and ecosystems
    MIYASHITA Kazushi  Nippon Suisan Gakkaishi  85-  (3)  294  -296  2019/05  [Not refereed][Invited]
  • 浅井咲樹, 浅井咲樹, 内田圭一, 内田圭一, 内田圭一, 宮本佳則, 宮本佳則, 宮本佳則, 宮下和士, 宮下和士, 宮下和士, 宮下和士, 白川北斗, 白川北斗, 白川北斗, 白川北斗, 荒井修亮, 荒井修亮, 三田村啓理, 三田村啓理, 北川貴士, 北川貴士, 笹倉豊喜, 笹倉豊喜  超音波Techno  31-  (1)  11‐16  2019/02/01  [Not refereed][Not invited]
  • 水産音響技術とその応用展開
    宮下和士, 甘糟和男  日本水産学会誌  84-  (特別)  44  -47  2018/11  [Not refereed][Invited]
  • シラスの体形状の測定とターゲットストレングスの理論推定
    加藤謙治, 甘糟和男, 南憲吏, 邵 花梅, 小林憲一, 宮下和士  海洋音響学会2018年度研究発表会講演論文集  47  -48  2018/05  [Not refereed][Not invited]
  • 村上弘章, 山本哲史, 源利文, 南憲吏, 宮下和士, 深谷肇一, 尹錫鎭, 笠井亮秀, 澤田英樹, 益田玲爾, 山下洋, 近藤倫生  日本水産学会大会講演要旨集  2018-  28  2018/03/26  [Not refereed][Not invited]
  • 浅井咲樹, 内田圭一, 内田圭一, 宮下和士, 宮下和士, 荒井修亮, 三田村啓理, 北川貴士, 北川貴士, 白川北斗, 白川北斗, 宮本佳則, 宮本佳則, 笹倉豊喜  海洋音響学会研究発表会講演論文集  2018-  2018
  • Shigehiko Urawa, Hitoshi Araki, Kazushi Miyashita, Mitsuhiro Nagata, Yoshitaka Sasaki, Masahide Kaeriyama  NIPPON SUISAN GAKKAISHI  84-  (5)  921  -921  2018
  • Estimating fish population abundance by integrating quantitative data on environmental DNA and hydrodynamic modelling
    Keiichi Fukaya, Hiroaki Murakami, Seokjin Yoon, Kenji Minami, Yutaka Osada, Satoshi Yamamoto, Reiji Masuda, Akihide Kasai, Kazushi Miyashita, Toshifumi Minamoto, Michio Kondoh  bioRxiv  482489  2018/01  [Not refereed][Not invited]
  • 林成幸, 津田裕一, 宇野睦実, 伊東隆臣, 恩田紀代子, 三谷曜子, 宮下和士  動物園水族館雑誌  58-  (1/2)  18‐19  2017/04/25  [Not refereed][Not invited]
  • Koki Tsujii, Mayuko Otsuki, Tomonari Akamatsu, Ikuo Matsuo, Minoru Kitamura, Takashi Kikuchi, Kazuo Amakasu, Kazushi Miyashita, Yoko Mitani  Techno-Ocean 2016: Return to the Oceans  49  -53  2017/03/30  [Not refereed][Not invited]
    Environmental changes are considered to affect the migration and distribution of baleen whales in the Arctic region. We examined the seasonal acoustic presence of fin whales (Balaenoptera physalus) and the relationships between acoustics and oceanographic environments in the southern Chukchi Sea from July 2012 to October 2015. Fin whale calls were detected from 4 August to 20 October 2012, from 25 July to 1 November 2013, from 26 July to 14 November 2014, and 7 June 2015, only in the ice-free (sea ice concentration = 0%) periods. In addition, from the recordings in 2012 and 2013, fin whale calls were present in the periods of high prey abundance, and there were significant positive correlations among their call presence, prey abundance, water temperature and salinity. Furthermore, the result that the calls were detected in 7 June 2015 suggests that fin whales arrive much earlier at the southern Chukchi Sea than previously reported. Our study provide valuable information to assess the impact on marine ecosystem in the Arctic region by environmental changes.
  • 三田村啓理, 三田村啓理, 荒井修亮, 市川光太郎, 宮本佳則, 内田圭一, 北川貴士, 北川貴士, 福田漠生, 藤岡紘, 宮下和士, 宮下和士  日本水産学会大会講演要旨集  2017-  2017
  • Mina Jimbo, Daisuke Mizuguchi, Koki Tsujii, Kazushi Miyashita, Yoko Mitani  The Journal of the Acoustical Society of America  140-  (4)  3303  -3303  2016/10
  • 海洋生物資源を理解して上手につきあう.
    宮下和士  北海道大学公開講座:「国のかたち」を案ずる時代の知恵・テキスト集  23  -27  2016  [Not refereed][Invited]
  • 山田綾子, 堀本高矩, 石塚真由美, 池中良徳, 中山翔太, 水川葉月, 三谷曜子, 宮下和士  日本水産学会大会講演要旨集  2015-  49  2015/03/27  [Not refereed][Not invited]
  • 資源の持続的利用方法の開発 音響資源調査
    徳光俊二, 高 宛愉, 富安 信, 宮下和士, 亘 真吾  平成25年度海洋水産資源開発事業報告書(ひきなわ・タチウオ<豊後水道周辺海域>)  7-  27  -36  2015  [Not refereed][Not invited]
  • 計量魚探による現存量調査.水産海洋地域研究集会「出口に向けた水産総合研究 ―豊後水道域のタチウオひきなわ漁業を例として―」.
    宮下和士, 富安信, 高宛愉, 安部幸樹, 南 吏, 濱田貴史, 竹下文雄, 高橋竜三, 三谷曜子  水産海洋研究  79-  188  -189  2015  [Not refereed][Invited]
  • Kazushi Miyashita, Takashi Kitagawa, Yoshinori Miyamoto, Nobuaki Arai, Hokuto Shirakawa, Hiromichi Mitamura, Takuji Noda, Toyoki Sasakura, Tomio Shinke  NIPPON SUISAN GAKKAISHI  80-  (6)  1009  -1015  2014/11  [Not refereed][Not invited]
  • 岩原由佳, 関口圭子, 松野孝平, 中野翼, 西沢文吾, 鵜山貴司, 山口篤, 綿貫豊, 宮下和士, 三谷曜子  日本水産学会大会講演要旨集  2014-  107  2014/03/27  [Not refereed][Not invited]
  • 資源の持続的利用方法の開発 計量魚探調査
    徳光俊二, 亘 真吾, 竹下文雄, 園木詩織, 高 宛愉, 富安 信, 宮下和士  平成24年度海洋水産資源開発事業報告書(ひきなわ・タチウオ<豊後水道周辺海域>)  8-  48  -50  2014  [Not refereed][Not invited]
  • 石田太朗, 安間洋樹, 南憲史, 道家章生, 西垣友和, 宮下和士, 藤森康澄  日本水産学会大会講演要旨集  2013-  6  2013/09/19  [Not refereed][Not invited]
  • 三谷曜子, 岩原由佳, 関口圭子, 松野孝平, 山口篤, 宮下和士  極域科学シンポジウム講演予稿集(CD-ROM)  4th-  ROMBUNNO.IA,MITANIYOKO,1,V3  2013  [Not refereed][Not invited]
  • ミナミマグロ幼魚の生息環境選択.総特集「電子標識を用いた高度回遊性魚類の生態研究の現状」
    藤岡紘, 河邊玲, A. J. Hobday, 宮下和士, 高尾芳三, 境麿, 伊藤智幸  月刊海洋  45-  90  -102  2013  [Not refereed][Not invited]
  • 計量魚群探知機を用いたガラモ場の現存量推定
    南 憲吏, 安間洋樹, 濱野 明, 東条斉興, 中村武史, 宮下和士  海洋音響学会2012年度研究発表会講演論文集  1  -2  2012/06  [Not refereed][Not invited]
  • 生物多様性と海洋生態系計測学.WS海洋生物多様性の把握に関する科学的ニーズと先端計測技術シーズの邂逅
    宮下 和士  JST研究開発戦略センター報告書  42  -44  2012  [Not refereed][Invited]
  • 村瀬 弘人, 田村 力, 磯田 辰也, 岡本 亮介, 加藤 秀弘, 米崎 史郎, 渡邉 光, 東条 斉興, 松倉 隆一, 宮下 和士, 木和田 広司, 松岡 耕二, 西脇 茂利, 稲掛 伝三, 岡崎 誠, 岡村 寛, 藤瀬 良弘  水産海洋研究  75-  (3)  180  -181  2011/08/01
  • 小野寺 恵一, 永島 宏, 松倉 隆一, 宮下 和士, 村瀬 弘人  宮城県水産研究報告  (11)  87  -90  2011/03  
  • SAFRUDDIN, ITO YUSUKE, YASUMA HIROKI, ITAYA KAZUHIKO, MAEDA KEIJI, MIYASHITA KAZUSHI  日本水産学会北海道支部大会講演要旨集  2011-  54  2011  [Not refereed][Not invited]
  • シラス魚群マップの紹介
    宮下和士  海洋水産エンジニアリング  96-  21  -26  2011  [Not refereed][Invited]
  • 宮下和士  日本水産学会誌  77-  300  -303  2011  [Not refereed][Invited]
  • 計量魚探による鯨類餌生物のモニタリング
    宮下和士, 松倉隆一, 東条斉興, 南憲吏, 安間洋樹, 永島宏, 小野寺恵一, 渡邉 光, 米崎史郎, 村瀬弘人  水産海洋研究  75-  183  -184  2011  [Not refereed][Not invited]
  • 北西太平洋沖合域におけるミンククジラ,イワシクジラ,ニタリクジラの餌選択性
    村瀬弘人, 田村力, 磯田辰也, 岡本亮介, 加藤秀弘, 米崎史郎, 渡邉光, 東条斉興, 松倉隆一, 宮下和士, 木和田広司, 松岡耕二, 西脇茂利, 稲掛伝三, 岡崎誠, 岡村寛, 藤瀬良弘  水産海洋研究  75-  183  -184  2011  [Not refereed][Not invited]
  • 仙台湾における鯨類餌環境調査
    小野寺恵一, 永島宏, 松倉隆一, 宮下和士, 米崎史郎, 村瀬弘人  水産海洋研究  75-  184  -185  2011  [Not refereed][Not invited]
  • 三谷 曜子, 岡崎 宏美, 関口 圭子, 宮下 和士  Bulletin of Fisheries Sciences, Hokkaido University  61-  (2/3)  65  -74  2011  [Not refereed][Not invited]
    Killer whales Orcinus orca are cosmopolitan in distribution, but study sites are restricted to small geographic areas, primarily shore-based and boat-based studies focusing on nearshore areas. To contribute understanding about the biology of killerwhales in pelagic areas, we created photographic identification catalogue of killer whales sighted during T/S Oshoro-maru cruise to the northern North Pacific, Bering Sea and Chukchi Sea in 2003, 2005-2009. For 6 years, 37 groups were found, containing 182 whales, and 29 individuals were identified from left side photos of dorsal fin. No individual was re-sighted within-year, nor between-year. And no matches were found between killer whales observed in Alaska, Russian far east seas, Kushiro and Shiretoko, Japan. Our result can serve as background information for the future study of pelagic killer whales.
  • 村瀬弘人, 川端淳, 久保田洋, 中神正康, 甘糟和男, 安部幸樹, 宮下和士, 大関芳沖  日本水産学会大会講演要旨集  2010-  7  2010/09/22  [Not refereed][Not invited]
  • 山口浩志, 高柳志朗, 佐野稔, 前田圭司, 宮下和士, 畑中勝守, 戸田真志, 岡本誠, 和田雅昭  日本水産学会大会講演要旨集  2010-  99  2010/09/22  [Not refereed][Not invited]
  • 永延 幹男, 藤瀬 良弘, 村瀬 弘人, 古谷 研, 宮下 和士  Bulletin of the Japanese Society of Fisheries Oceanography  74-  (1)  33  -34  2010/02/01
  • カタクチイワシシラスの遊泳姿勢とターゲットストレングスの推定
    伊藤 祐介, 守佐保, 南 憲吏, 益田 玲爾, 宮下 和士  平成22年度日本水産学会春季大会  2010  [Not refereed][Not invited]
  • 佐野稔, 前田圭司, 高柳志朗, 和田雅昭, 畑中勝守, 戸田真志, 岡本誠, 宮下和士  水産海洋学会研究発表大会講演要旨集  2010-  58  2010  [Not refereed][Not invited]
  • ITAYA Kazuhiko, MIYAKE Hiroya, WADA Akihiko, MIYASHITA Kazushi  Bulletin of the Japanese Society of Fisheries Oceanography  73-  (2)  80  -89  2009/05/28  
  • 計量魚探機を用いたマイクロネクトンの現存量推定法の開発.
    宮下和士, 安間洋樹  研究成果第461集「海洋生物資源の変動要因の解明と高精度変動予測技術の開発」(農林水産技術会議編)  461-  200  -205  2008  [Not refereed][Not invited]
  • Regime shift of mesopelagic fish – long term biomass index change of Maurolicus japonicus in the Japan Sea.
    Tadanori Fujino, Kazushi Miyashita, Hiroki Yasuma, Tsuyoshi Shimura, Shinya Masuda, Tuneo Goto  GLOBEC International newsletter  14-  (1)  35  -36  2008  [Not refereed][Not invited]
  • Estimation of prey preference of common minke whales (Balaenoptera acutorostrata) in a coastal component (off Sanriku) of JARPNII from 2005 to 2006
  • Distribution patterns and biomasses of Antarctic krill (Euphausia superba) and ice krill (E. crystallorophias) with note on distribution of Antarctic minke whales (Balaenoptera bonaerensis) in the Ross Sea in 2005
    Hiroto Murase, Hiroki Yasuma, Ryuichi Matsukura, Yoshimi Takao, Kenji Taki, Tomonari Hayashi, Takashi Yabuki, Tsutomu Tamura, Kenji Konishi, Koji Matsuoka, Kazushi Miyashita, Shigetoshi Nishiwaki, Mikio Naganobu  2008CCAMLR-EMM report  1  -14  2008  [Not refereed][Not invited]
  • 計量魚探機を用いたマイクロネクトンの現存量推定法の開発
    農林水産技術会議研究成果第461集  462-  200  -205  2008  [Not refereed][Not invited]
  • 宮下 和士  水産海洋研究  71-  (4)  279  -279  2007/11/08
  • 伊藤祐介, 濱野明, 田上英明, 中村武史, 宮下和士  日本水産学会大会講演要旨集  2007-  116  2007/09/25  [Not refereed][Not invited]
  • Video analysis of the schooling behaviour of juvenile chum salmon under light and dark conditions using mathematical model.
    Katsuya Suzuki, Tsutomu Takagi, Kazushi Miyashita  North Pacific Anadrmous Fish Commission Technical Report  7-  132  -131  2007  [Not refereed][Not invited]
  • 紀伊水道におけるカタクチイワシシラスの音響モニタリングについて.水産海洋地域研究集会「水産資源の音響モニタリングに向けて」.
    守岡佐保, 宮下和士, 渡邉九  水産海洋研究  71-  290  -292  2007  [Not refereed][Not invited]
  • ホンダワラ類の気胞の音響散乱特性
    南 憲吏, 濱野 明, 高尾芳三, 中村武史, 宮下和士  海洋音響学会2006年度研究発表会講演論文集  1  -2  2006/05  [Not refereed][Not invited]
  • 宮下和士  フィールド科学への招待  129  -139  2006
  • 高解像度の魚群探知機による魚の行動解析.第36回北洋シンポジウム「海洋生態系における高次捕食者の行動研究のための新技術」.
    宮下和士  水産海洋研究  70-  140  -141  2006  [Not refereed][Not invited]
  • 本邦周辺におけるハダカイワシ科魚類の鰾形態とターゲットストレングス
    安間洋樹, 澤田浩一, 高尾芳三, 宮下和士  平成17年度海洋音響学会講演論文集  5  -8  2005  [Not refereed][Not invited]
  • Acoustic sampling, In Micronekton of the North Pacific
    Richard Brodeur, Kazushi Miyashita  PICES Scientific Report  30-  73  -76  2005  [Not refereed][Not invited]
  • 藤岡紘, 光永靖, 津田裕一, 平石智徳, 有賀誠, 河辺玲, 宮下和士  日本水産学会大会講演要旨集  2004-  79  2004/03/31  [Not refereed][Not invited]
  • Analysis of fish schools migration direction and migration velocity from scanning sonar
    Kazushi Miyashita, Katsuya Suzuki, Sin-ichi Fukui  Proc. SBT Recruitment Monitoring Review Workshop  24  -26  2004  [Not refereed][Not invited]
  • 石狩川中流域におけるシロザケの遡上実態 -超音波テレメトリーによる遡上追跡調査をとおして-.
    有賀誠, 三上孝雄, 井上涼子, 津田裕一, 藤岡 紘, 河邊 玲, 光永 靖, 宮下和士  応用生態工学会第8回大会講演論文集  1  -4  2004  [Not refereed][Not invited]
  • 海洋GISの鉛直方向への応用, 海洋GISと空間解析 -そのサイエンスと未来-
    宮下和士  月刊海洋  36-  (5)  415  -420  2004  [Not refereed][Not invited]
  • デジタル・スチール・ロガーによるスケトウダラの遊泳行動観察
    鳥澤眞介, 宮下和士, 河邊 玲, 藤森康澄, 大島達樹, 本田 聡, 佐藤克文  日本水産学会漁業懇話会  47-  64  -65  2003  [Not refereed][Not invited]
  • 海洋環境と海洋資源に関する情報可視化.
    鉄村光太郎, 宮下和士  計算工学講演会論文集  8-  881  -884  2003  [Not refereed][Not invited]
  • 海洋情報のセンシングと可視化について.
    鉄村光太郎, 宮下和士  第6回問題解決環境ワークショップ論文集  111  -114  2003  [Not refereed][Not invited]
  • Acoustic and sampling gear surveys for estimating the abundance of aquatic living resources.
    Kazushi Miyashita, Koutarou Tetsumura  Proceedings of 1st Japan-Korea Joint Seminar on Fisheries Sciences  79  -80  2001  [Not refereed][Not invited]
  • 体積散乱強度の周波数差を用いる生物種判別.
    姜明希, 古澤昌彦, 濱田悦之, 宮下和士  平成12年度海洋音響学会講演論文集  73  -76  2000  [Not refereed][Not invited]
  • ソナー・魚探,第27回かつお・まぐろ漁業研究座談会.
    西田勤, 稲垣正, 宮下和士  水産海洋研究  62-  273  -276  1998  [Not refereed][Not invited]
  • Preliminary acoustic survey data analyses for juvenile southern bluefin tuna (Thunnus maccoyii) (1996-97).
    Tsutomu Nishida, Tadashi Inagaki, Kazushi Miyashita, J. L. Laake  Proceedings of the International workshop on acoustic surveys of North Pacific Fisheries Resources  1  -10  1997  [Not refereed][Not invited]

Awards & Honors

  • 2019/03 日本水産学会 水産学進歩賞
    受賞者: 宮下 和士
  • 2015 北海道大学 総長賞(奨励賞)
    受賞者: 宮下 和士
  • 2011 日本弁理士会会長奨励賞
  • 2009 平成21年度(第16回)河川整備基金助成事業優秀成果
  • 2009 平成21年度海洋音響学会論文賞
  • 2008 平成20年度(第15回)河川整備基金助成事業優秀成果
  • 2006 情報処理学会北海道支部技術研究賞

Research Grants & Projects

  • 海洋生態系の動態解析に関する研究
    Date (from‐to) : 2002 -2017
  • 海洋生物資源の空間的可視化技術の高度化に関する研究
    Date (from‐to) : 1998 -2017
  • 海洋生物資源の持続的利用に関する研究
    Date (from‐to) : 1998 -2017
  • 海洋生物の行動計測に関する研究
    Date (from‐to) : 1997 -2017
  • Quantitative Spatial Visualization of Aquatic Living Resources
    Date (from‐to) : 1998
  • スマート水産業に関する研究

Educational Activities

Teaching Experience

  • Special Lecture in Biosphere Science II
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : Aquatic Biology, Marine Ecology, Oceanography
  • Laboratory and Field Work in Biosphere Science I
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 精子、卵、発生、分化、受精、オルガネラ、生活史、個体群、群集、モニタリング、センシング sperm, egg, development, differentiation, fertilization, organelle, gamete, life history, population, community, monitoring, sensing
  • Laboratory and Field Work in Biosphere Science II
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 精子、卵、発生、分化、受精、オルガネラ、生活史、個体群、群集、モニタリング、センシング sperm, egg, development, differentiation, fertilization, organelle, gamete, life history, population, community, monitoring, sensing
  • Advanced Course in Aquatic Biology II
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 水圏動物、頭足類、スルメイカ、バイオロギング、バイオテレメトリー、海棲哺乳類、高次捕食者、生物多様性、生物地理要素 Aquatic animals, bio-logging, bio-telemetry, cephalopod, Japanese flying squid, marine mammals, top predators, selective breeding, biodiversity, biogeological elements
  • Fundamental Course in Field Sciences
    開講年度 : 2021
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 生物資源創成、共生生態系保全、持続的生物生産、生物多様性、生態系機能、生物群集生態 Bio-resources development, Ecosystem conservation, Sustainable bio-production, Biodiversity, Ecosystem function, Population and community ecology
  • Teaching Method of School Subjects(Fishery Ⅱ)
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 教育学部
    キーワード : 資源増殖、海洋漁業、海洋工学、情報通信、水産食品
  • Environment and People
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : サケ、回遊、人工ふ化放流、分類、気候変化、資源変動、生活史、個体群密度効果、生物多様性、バイオロギング、母川回帰、嗅覚、物質循環、海水適応、ゲノム、性統御、始原生殖細胞、流通、食品,機能性素材、アスタキサンチン,考古学、先住民族、市民運動
  • Laboratory Work on Marine Resources Ⅲ
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 行動生態計測、衛星データ解析-マイクロ波リモートセンシング、海洋観測データ解析、魚類遊泳力学,魚類行動計測、水産海洋工学、数値流体解析
  • Arts and Science Courses in English 2
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 国際本部
    キーワード : Ecosystem conservation, Sustainable bioproduction, Biodiversity, Material cycling, Harmonizable relation between human and environment
  • English Seminar
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 生態系保全、持続的生物生産、生物多様性、物質循環、人間環境共生系
  • General Education Seminar
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 総合教育部
    キーワード : 生態系保全、持続的生物生産、生物多様性、物質循環、人間環境共生系
  • General Education Seminar
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 現代日本学プログラム課程
    キーワード : 生態系保全、持続的生物生産、生物多様性、物質循環、人間環境共生系
  • Aquatic Ecology in the Northern Biosphere
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 生態系 生態 資源 計測 モニタリング 持続可能性
  • Environment and People
    開講年度 : 2021
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 生物資源創成、共生生態系保全、持続的生物生産、生物多様性、生態系機能、生物群集生態

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