Researcher Profile and Settings

Master

Affiliation (Master)

• Faculty of Fisheries Sciences　Marine Bioresource and Environmental Science　Marine Bioresource Science

Affiliation (Master)

• Faculty of Fisheries Sciences　Marine Bioresource and Environmental Science　Marine Bioresource Science

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Profile and Settings

Degree

• Doctor (Fisheries)（1998/12 Hokkaido University）

Profile and Settings

• Name (Japanese)

  Takatsu

• Name (Kana)

  Tetsuya

• Name

  200901066478379535

Alternate Names

http://www2.fish.hokudai.ac.jp/faculty-member/takatsu-tetsuya/?key=jp
http://www2.fish.hokudai.ac.jp/faculty-member/takatsu-tetsuya/?key=en

Achievement

Research Interests

• スケトウダラ   ホッケ   キアンコウ   トヤマエビ   ソウハチ   プランクトン   クモヒトデ   マダラ   日周輪   耳石   耳石日周輪   餌密度   水産学   鉛直分布   水塊   生態   仔魚   成長速度   卵   加入   食性   分布密度   成長率   イカナゴ   初期生活史   卓越年級群   孵化日組成   水温   アカガレイ   行動   稚魚   分布   マコガレイ   成長   ソリネット   魚類生態学   Early Life Histories of Marine Fishes (6301)   Population Dynamics of Fisheries Recources (6301)   Fish Ecology (6301)   

Research Areas

• Life sciences / Aquaculture

Research Experience

• 2010/04 Faculty of Fisheries Sciences, Hokkaido Univ. Division of Marine Bioresource and Environmental Science, Laboratory of Marine Bioresource Science Professor
• 2006/04 - 2010/03 Faculty of Fisheries Sciences, Hokkaido Univ. Division of Marine Bioresource and Environmental Science, Laboratory of Marine Bioresource Science Associate Professor
• 2010 - 大学院水産科学研究院 海洋生物資源科学部門 資源生物学分野 教授
• 1995/04 - 2006/03 Graduate School of Fisheries Siences, Hokkaido Univ. Laboratory of Marine Biorecources Ecology Assistant Profeser
• 1992/07 - 1995/03 Faculty of Fisheries, Hokkaido Univ. Laboratory of Principals of Fishing Ground Assistant Profeser
• 1992 - 1995 水産学部 漁業学科 漁場学講座 助手

Education

• 1991/04 - 1992/06  Hokkaido University  Graduate School of Fisheries  Doctor Course
• 1989/04 - 1991/03  Hokkaido University  Graduate School of Fisheries  Master Course
• 1988/04 - 1989/03  Hokkaido University  Faculty of Fisheries  Specialized Training Course
• 1984/04 - 1988/03  Hokkaido University  Faculty of Fisheries  Fisheries Science

Committee Memberships

• 2023/08 - Today   Hokkaido Oshima Sea-area Fisheries Adjustment Committee   Committee member
• 2023/03 - Today   Fisheries Oceanography Associate Editor
• 2020/04 - Today   The Japanese Society of Fisheries Science   Hokkaido Branch Secretary
• 2021/05 -2024/03   Japanese Society for Aquaculture Science   Vice President

Awards

• 2018/03 The Japanese Society of Fisheries Oceanography Dr. Uda Award
   Early life histories and population dynamics of demersal fishes in subarctic waters 

  受賞者: TAKATSU Tetsuya
• 2017/06 Fisheries Oceanography, Wiley Reviewer Award of Fisheries Oceanography (14 manuscripts in 2016)
   

  受賞者: TAKATSU Tetsuya
• 2015/03 Hokkaido University Award for Primary Education in Hokkaido University
   

  受賞者: TAKATSU Tetsuya
• 2012/03 Plankton Society of Japan Best Paper Award of the Plankton Society of Japan
   Feeding habits of two-flatfish-species larvae in Funka Bay, Japan. – importance of Oikopleura as prey - 

  受賞者: YUTARO HASHIMOTO;AKIKO MAEDA;YUSUKE OONO;YOTA KANO;TETSUYA TAKATSU
• 2003 平成14年度日本水産学会奨励賞
  
• 2003 Achievement Award for Young Scientist: The Japanese Society of Fisheries Science Awards 2002
  
• 2000 パイセス第９回年次総会(PICES IX)ベストポスター賞
  
• 2000 North Pacific Marine Science Organization, 9th Annual Meeting; Best Poster Award
  

Published Papers

• Macroscopic and microscopic morphological characteristics of gelatinous egg masses (egg veils) of yellow goosefish Lophius litulon (Lophiiformes; Lophiidae)

  Tomoya Ishikawa, Mitsuhiro Nakaya, Yuta Eno, Tetsuya Takatsu

  J Fish Biol 2024/07 [Refereed][Not invited]
  
• Spawning ground selection and larval feeding habits of Arabesque greenling Pleurogrammus azonus around the Matsumae Peninsula, Japan

  Tetsuya Takatsu, Tomoaki Toyonaga, Shin’ya Hirao, Eri Ooka, Naoto Kobayashi, Mitsuhiro Nakaya

  Fisheries Science 90 (3) 435 - 452 2024/04 [Refereed][Not invited]
  
• Distinct gut microbial communities and functional predictions in divergent ophiuroid species: host differentiation, ecological niches, and adaptation to cold-water habitats

  Yue Dong, Yixuan Li, Meiling Ge, Tetsuya Takatsu, Zongling Wang, Xuelei Zhang, Dewen Ding, Qinzeng Xu

  Microbiology Spectrum 11 (6) 2023/12/12 [Refereed]
   

  ABSTRACT Gastrointestinal microorganisms play a crucial role in host survival and adaptation, but information on host-specific selection or environmental factors that shape the microbiome in natural populations is limited. In this study, we employed 16S rRNA gene amplicon sequencing to investigate the composition and predicted the functions of gut microbiota of two ophiuroid species ( Ophiura sarsii and its subspecies O. sarsii vadicola ) from cold-water habitats across three geographically distant sea areas in the Northern Pacific Ocean. We also explored the potential influence of the host and environment on the microbiota. The two ophiuroids possessed diverse microbial communities, with Proteobacteria being the most dominant phylum in all four groups. Aliivibrio was the predominant genus in O. sarsii from the Bering Sea, while Candidatus Hepatoplasma was the dominant genus in O. sarsii from the Japan Sea and O. sarsii vadicola from the Yellow Sea. Predicted bacterial functions indicated that most of the pathways with significant differences belonged to metabolism and genetic information processing. Notably, no significant difference was observed between the two coexisting ophiuroid species in the Japan Sea. The high similarity in microbial communities between O. sarsii from the Japan Sea and O. sarsii vadicola from the Yellow Sea may be attributed to their analogous ecological niche. The host and the environment jointly shape the composition of the gut microbial community. The presence of specific microorganisms supports the ecological success of ophiuroids across diverse environments, providing a foundation for host adaptation to cold-water habitats. IMPORTANCE Gastrointestinal microorganisms are critical to the survival and adaptation of hosts, and there are few studies on the differences and functions of gastrointestinal microbes in widely distributed species. This study investigated the gut microbes of two ophiuroid species ( Ophiura sarsii and its subspecies O. sarsii vadicola ) in cold-water habitats of the Northern Pacific Ocean. The results showed that a combination of host and environmental factors shapes the intestinal microbiota of ophiuroids. There was a high similarity in microbial communities between the two groups living in different regions, which may be related to their similar ecological niches. These microorganisms played a vital role in the ecological success of ophiuroids as the foundation for their adaptation to cold-water environments. This study revealed the complex relationship between hosts and their gut microbes, providing insights into the role they play in the adaptation and survival of marine species.
• Significant nutrient consumption in the dark subsurface layer during a diatom bloom: a case study on Funka Bay, Hokkaido, Japan

  Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu, Atsushi Ooki

  Biogeosciences 20 (2) 421 - 438 2023/01/27 

  Abstract. We conducted repetitive observations in Funka Bay,Hokkaido, Japan, on 15 February, 4 and 15 March, and 14 April 2019. Thediatom spring bloom peaked on 4 March and started declining on 15 March.Funka Bay winter water remained below 30 m depth, which was below thesurface mixed-layer and dark-layer depth (0.1 % of the surface photosynthetically active radiation, PAR, depth) on 4and 15 March. In the subsurface layer at depths of 30–50 m, concentrationsof NO3-, PO43-, and Si(OH)4 decreased by halfbetween these dates, even in the dark. Incubation experiments using thediatom Thalassiosira nordenskioeldii showed that this diatom could consume added nutrients in the dark atsubstantial rates after pre-culturing to deplete nutrients. Incubationexperiments using natural seawater collected in the growing phase of the bloom on 8 March 2022 also showed that nutrient-depleted phytoplankton could consumeadded nutrients in the dark. We excluded three physicalprocess – water mixing, diffusive transport, and subduction – as possible mainreasons for the decrease in nutrients in the subsurface layer. We concludethat the nutrient reduction in the subsurface layer (30–50 m) between 4 and15 March 2019 could be explained by nutrient consumption by diatoms in the dark in thatlayer.
• Intrusion of Coastal Oyashio water to Funka Bay and Tsugaru Strait occasionally disturbed by Kuroshio-originating warm core ring

  H. Abe, Y. Yahiro, T. Hasegawa, T. Hirawake, H. Onishi, A. Ooki, T. Takatsu, K. Sasaki, M. Wakita, H. Kaneko, S. Watanabe, T. Tanaka, T. Okunishi, S. Ohno, S. Hashizume

  Journal of Oceanography 0916-8370 2023/01/09 [Refereed]
  
• Seasonal changes in taxonomic, size composition, and Normalised Biomass Size Spectra (NBSS) of mesozooplankton communities in the Funka Bay, southwestern Hokkaido: Insights from ZooScan analysis

  Takumi Teraoka, Kanako Amei, Yutaka Fukai, Kohei Matsuno, Hiroji Onishi, Atsushi Ooki, Tetsuya Takatsu, Atsushi Yamaguchi

  Plankton and Benthos Research 17 (4) 369 - 382 1880-8247 2022/11/30
• Marine sediment as a likely source of methyl and ethyl iodides in subpolar and polar seas

  Atsushi Ooki, Keita Minamikawa, Fanxing Meng, Naoya Miyashita, Toru Hirawake, Hiromichi Ueno, Yuichi Nosaka, Tetsuya Takatsu

  Communications Earth & Environment 3 (1) 2022/08/12 [Refereed][Not invited]
   

  Abstract The surface ocean is an important source of longer-lived volatile organic iodine compounds, such as methyl and ethyl iodide. However, their production in deep waters is poorly constrained. Here, we combine shipborne seawater and sediment core analyses to investigate the temporal and vertical distribution of methyl and ethyl iodide concentrations in the Bering and Chukchi Seas in July 2017 and 2018, and Funka Bay, Japan, between March 2018 and December 2019. We find the highest methyl and ethyl iodide concentrations in sediment porewaters and at the sediment surface. In Funka Bay, concentrations in the sediment and bottom waters strongly increased following the spring bloom and subsequent settling of phytodetritus to the seafloor. Dark incubation experiments suggest that diatom aggregates are a source of methyl and ethyl iodide to the ambient water. Our findings suggest that phytodetritus at the seafloor is a potential source of volatile organic iodine compounds to the water column in polar and subpolar coastal oceans.
• Changes in morphology and specific gravity in larvae of Lophius litulon (Lophiiformes; Lophiidae) before and after emergence from egg veil

  Tomoya Ishikawa, Mitsuhiro Nakaya, Weifeng Gao, Tetsuya Takatsu, Kenji Odani, Ryo Suzuki, Kyosei Noro, Yuhei Takeya

  Environmental Biology of Fishes 105 (2) 303 - 312 0378-1909 2022/02 [Refereed][Not invited]
  
• Effect of egg size on the growth rate and survival of wild walleye pollock Gadus chalcogrammus larvae

  Keitaro Kajiwara, Mitsuhiro Nakaya, Kota Suzuki, Yota Kano, Tetsuya Takatsu

  Fisheries Oceanography 31 (3) 238 - 254 1054-6006 2022/02 [Refereed][Not invited]
  
• Nutrient consumption by diatoms in the dark subsurface layer of Funka Bay, Hokkaido, Japan

  Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu, Atsushi Ooki

  2022/01/06 [Refereed]
   

  Abstract. We conducted time-series observations in Funka Bay, Hokkaido, Japan, from 15 February to 14 April 2019. The diatom spring bloom peaked on 4 March and started declining on 15 March. Funka Bay winter water remained below 30-m depth, which was below the surface mixed-layer and dark-zone depths on both dates. At depths of 30–50 m, concentrations of NO3–, PO43–, and Si(OH)4 decreased by half between these dates even in darkness. Incubation experiments using the diatom Thalassiosira nordenskioeldii showed that this diatom could consume nutrients in darkness at substantial rates. We conclude that the nutrient reduction in the subsurface layer (30–50 m) could be explained by dark consumption by diatoms that had been growing in the surface waters and then sank to the subsurface layer. We believe that this is the first study to present observational evidence for the consumption of the main nutrients by diatoms in the dark subsurface layer during the spring bloom. Nutrient consumption in this layer might have a substantial influence on the primary production during and after the spring bloom.
• Isoprene production in the water column and sediment in Funka Bay, Hokkaido, Japan

  Atsushi Ooki, Naoya Miyashita, Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu

  GEOCHEMICAL JOURNAL 56 (5) 142 - 150 0016-7002 2022 [Refereed][Not invited]
  
• Embryonic development and effect of water temperature on hatching of Lophius litulon

  Tomoya Ishikawa, Mitsuhiro Nakaya, Tetsuya Takatsu

  Environmental Biology of Fishes 105 (1) 77 - 86 0378-1909 2022/01 [Refereed][Not invited]
  
• Effect of water temperature on the embryonic period of Pacific rainbow smelt Osmerus dentex

  Tran Nguyen Hai NAM, Mitsuhiro NAKAYA, Tomoya ISHIKAWA, Tetsuya TAKATSU

  Aquaculture Science 2021 (3) 223 - 225 2021/10 [Refereed][Not invited]
  
• Coloration of a small Nozawa’s prickleback, Stichaeus nozawae Jordan and Snyder, 1902 (Zoarcoidei : Stichaeidae)

  Obata Kota, Kawai Toshio, Takatsu Tetsuya

  Bulletin of Fisheries Sciences, Hokkaido University 71 (1) 15 - 20 2021/08 [Not refereed]
  
• Age and growth of Pacific rainbow smelt Osmerus dentex estimated from scales and otoliths in Funka Bay and the Yamazaki River, Japan

  Tran Nguyen Hai NAM, Mitsuhiro NAKAYA, Tetsuya TAKATSU

  Aquaculture Science 2021 (2) 153 - 161 2021/07 [Refereed][Not invited]
  
• Validation of otolith daily increment formation and growth analysis of yellow goosefish Lophius litulon

  Weifeng Gao, Mitsuhiro Nakaya, Tomoya Ishikawa, Tetsuya Takatsu, Yuhei Takeya, Ryo Suzuki, Kyosei Noro

  Fisheries Science 87 (4) 541 - 548 0919-9268 2021/07 [Refereed][Not invited]
  
• Isoprene production in seawater of Funka Bay, Hokkaido, Japan

  Atsushi Ooki, Ryuta Shida, Masashi Otsu, Hiroji Onishi, Naoto Kobayashi, Takahiro Iida, Daiki Nomura, Kota Suzuki, Hideyoshi Yamaoka, Tetsuya Takatsu

  Journal of Oceanography 75 (6) 485 - 501 0916-8370 2019/12 [Refereed][Not invited]
  
• Annual and seasonal changes in the assemblage of planktonic copepods and appendicularians in Funka Bay before and after intrusion of Coastal Oyashio Water

  Hideyoshi Yamaoka, Tetsuya Takatsu, Kota Suzuki, Naoto Kobayashi, Atsushi Ooki, Mitsuhiro Nakaya

  Fisheries Science 85 (6) 1077 - 1087 2019/09 [Refereed][Not invited]
  
• Elucidation of the life histories and population dynamics of dominant demersal fish in the subarctic zone

  TAKATSU Tetsuya

  Bull. Jpn. Soc. Fish. Oceanogr. 83 (3) 191 - 196 2019/08 [Not refereed][Invited]
  
• Growth of the brittle star Ophiura sarsii sarsii in Funka Bay, Hokkaido, Japan

  Kazuki Orino, Kosuke Ishigane, Kota Suzuki, Hiroki Izumiura, Mitsuhiro Nakaya, Tetsuya Takatsu

  Fisheries Science 85 (4) 705 - 716 2019/08 [Refereed][Not invited]
   

  The brittle star Ophiura sarsii with a disc diameter (DD) of less than 9 mm is an important prey item for flathead flounder
  Hippoglossoides dubius in Funka Bay. To establish an age-determination technique and estimate the growth equation for Ophiura sarsii sarsii (a dominant sub-species of O. sarsii in Funka Bay), we observed ridges on the surface of the arm ossicles. Specimens were collected using a sledge net, their DD measured, and the first arm ossicles examined from scanning electron microscopy images. Because the outermost ridges were formed from November to March, ridges were identified
  as yearly rings (annuli). The maximum age was 16.83 years (16.46-mm DD), and the largest sized individual was 22.19 mm DD (13.75 years). The best growth equation between DD and age (t) was given by Richard’s model using a minimum Akaike’s information criterion and growth rate comparison: DDt=
  24.02 × {1 − 1.70 × exp[− 0.067 × (t + 8.25)]}−1/(−1.70). Small-sized (< 9-mm DD) and large-sized (ca. 15-mm DD) cohorts were composed of multi-year classes, and estimated
  growth rates from cohort progressions were 2.25 mm/year and 0.98 mm/year, respectively. We presumed that the large-sized cohort could be explained by a high survival rate and slow growth rate after the age of 5 or 6 years.
• Genetic diversity of the flathead flounder Hippoglossoides dubius population in Funka Bay inferred from mitochondrial DNA analysis. Japan

  Yuki Yamamoto, Minoru Ikeda, Mitsuhiro Nakaya, Kota Suzuki, Tetsuya Takatsu

  Japanese Journal of Ichthyology 65 (1) 75 - 80 2018/04 [Refereed][Not invited]
   

  The flathead flounder Hippoglossoides dubius population in Funka Bay, characterized by unique ecological features, has been thought to be demographically independent of other conspecific populations. To clarify such, sequence data of the hyper variable domain in the mitochondrial DNA control region was collected from the Funka Bay population and the genetic diversity compared with previously published data for other populations (Sea of Japan and northwestern Pacific off Tohoku–Hokkaido). Because the level of diversity of the former population differed little from that of other populations, with no significant genetic differentiation detected, it is likely that contemporary or recent historical gene flow has occurred extensively in Japanese coastal waters. The likelihood of gene flow and connectivity among the populations, all characterized by long pelagic egg and larval stages, being associated with the Tsugaru Warm Current is considered.
• Sexual dimorphism in the size of bulbous nasal tubes of yellow goosefish Lophius litulon oŠ Aomori Prefecture, northern Japan

  Yuhei Takeya, Tetsuya Takatsu, Tomoyuki Yamanaka, Yasutoki Shibata, Mitsuhiro Nakaya

  Nippon Suisan Gakkaishi (Japanese Edition) 84 (1) 130 - 132 1349-998X 2018 [Refereed][Not invited]
  
• Otolith microstructure of Arabesque greenling Pleurograrnmus azonus: A species with a long embryonic period

  Savitri Marannu, Mitsuhiro Nakaya, Tetsuya Takatsu, Shin-ichi Takabatake, Mikimasa Joh, Yutaro Suzuki

  FISHERIES RESEARCH 194 129 - 134 0165-7836 2017/10 [Refereed][Not invited]
   

  We investigated the relationship between morphological development in the embryonic stage and the formation of otolith microstructure in Arabesque greenling Pleurogranunus azonus, and then validated that the otolith increments were formed on a daily basis. Increments were more consistent to count and measure in sagittal otoliths from wild caught larvae compared to lapillar otoliths, and we suggest that sagittal otoliths as suitable for otolith microstructure analysis. This study clarified the formation time of three prominent increments on the sagittal otolith. First prominent increment (approx. 17 mm in otolith radius (OR)) was coincident with the time of eye pigmentation in the embryonic stage. Second (approx. 36 pm OR) was considered to be the hatch increment and the third (approx. 38 pm OR) was at the time of transition from endogenous to exogenous nutrition. The third prominent increment which was the clearest radius (termed below as the check) was used as the starting point for validating the daily increment formation in sagittal otolith, and also there was no significant difference in the check radius among reared (6, 8, and 10 degrees C) and wild caught larvae. The relationship between number of days after hatching and the number of increments formed after check was significant and the slope of the regression line was not different from 1, validating the assumption that growth increments are formed on a daily basis in sagittae of P. azonus. The check was formed on the otolith at the transition from endogenous to exogenous nutrition, and the number of days required prior to its formation varied with water temperature. For the species in which the check is formed at the nutritional transition from endogenous to exogenous feeding, the relationship between number of days to check formation and water temperature is essential to estimate the hatch date of wild caught individuals.
• The effect of temperature on the early development and starvation tolerance of yellow goosefish Lophius litulon

  Mitsuhiro Nakaya, Yuhei Takeya, Ryo Suzuki, Kyosei Noro, Weifeng Gao, Tetsuya Takatsu

  Aquaculture Science 日本水産増殖学会 65 (3) 251 - 254 0371-4217 2017/09 [Refereed][Not invited]
  
• Relationship between temperature and embryonic period of Arabesque greenling Pleurogrammus azonus

  Mitsuhiro Nakaya, Savitri Marannu, Yuta Inagaki, Keitaro Kajiwara, Yoshitaka Sato, Kota Suzuki, Tetsuya Takatsu

  Aquaculture Science 日本水産増殖学会 65 (3) 247 - 250 0371-4217 2017/09 [Refereed][Not invited]
  
• Changes in the specific gravity of eggs, larvae, and juveniles of Hippoglosoides dubius, and the relationship between egg development and water temperature

  Kota Suzuki, Mitsuhiro Nakaya, Hae-Kyun Yoo, Taihei Matsuda, Tetsuya Takatsu

  NIPPON SUISAN GAKKAISHI 公益社団法人 日本水産学会 83 (4) 580 - 588 0021-5392 2017/07 [Refereed][Not invited]
   

  To assess transportation in the early life history stages in the flathead flounder Hippoglosoides dubius, we measured the specific gravities of the eggs at 9 degrees C and the larvae and juveniles at 9 degrees C and 12 degrees C using density gradient and density-bottle methods. We also examined the effect of temperature (1, 3, 6, 9, and 12 degrees C) on the duration between fertilization and yolk sac absorption. Eggs in glass beakers had lower specific gravities than the water densities experienced in one of the spawning grounds, Funka Bay. In contrast, the specific gravities were higher than the water densities in Funka Bay in yolk sac larvae, almost the same in early preflexion larvae, and increased with advancing development from the late preflexion larval to juvenile stages. The duration from fertilization to yolk sac period decreased with increasing water temperature. Thus, annual variation in the water temperature in the field combined with transport directions and speeds at various depths may affect the transportation of flounder eggs and larvae.
• Seasonal variation of volatile organic iodine compounds in the water column of Funka Bay, Hokkaido, Japan

  Yusaku Shimizu, Atsushi Ooki, Hiroji Onishi, Tetsuya Takatsu, Seiji Tanaka, Yuta Inagaki, Kota Suzuki, Naoto Kobayashi, Yoshihiko Kamei, Kenshi Kuma

  JOURNAL OF ATMOSPHERIC CHEMISTRY 74 (2) 205 - 225 0167-7764 2017/06 [Refereed][Not invited]
   

  Volatile organic iodine compounds (VOIs) emitted from the ocean surface to the air play an important role in atmospheric chemistry. Shipboard observations were conducted in Funka Bay, Hokkaido, Japan, bimonthly or monthly from March 2012 to December 2014, to elucidate the seasonal variations of VOI concentrations in seawater and their sea-to-air iodine fluxes. The bay water exchanges with the open ocean water of the North Pacific twice a year (early spring and autumn). Vertical profiles of CH2I2, CH2ClI, CH3I, and C2H5I concentrations in the bay water were measured bimonthly or monthly within an identified water mass. The VOI concentrations began to increase after early April at the end of the diatom spring bloom, and represented substantial peaks in June or July. The temporal variation of the C2H5I profile, which showed a distinct peak in the bottom layer from April to July, was similar to the PO4 (3-) variation profile. Correlation between C2H5I and PO4 (3-) concentrations (r = 0.93) suggests that C2H5I production was associated with degradation of organic matter deposited on the bottom after the spring bloom. CH2I2 and CH2ClI concentrations increased substantially in the surface and subsurface layers (0-60 m) in June or July resulted in a clear seasonal variation of the sea-to-air iodine flux of the VOIs (high in summer or autumn and low in spring).
• Feeding, somatic condition and survival of sand lance Ammodytes sp larvae in Mutsu Bay, Japan

  Nobuaki Nanjo, Tetsuya Takatsu, Kazuo Imura, Kingo Itoh, Yuuhei Takeya, Toyomi Takahashi

  FISHERIES SCIENCE 83 (2) 199 - 214 0919-9268 2017/03 [Refereed][Not invited]
   

  To clarify the recruitment process of sand lance Ammodytes sp., we investigated larval condition factor, relative gut fullness (%GF), prey abundance and oceanographic structure in Mutsu Bay, Japan, during 1999-2001. Ammodytes sp. larvae, which were collected by horizontal hauls of Motoda nets and a ring net at depths of 1, 10, 20, 30 and 40 m, were mainly distributed at 10-30 m. Larvae at the first feeding time until 12 mm in body length (BL) fed predominantly on copepod nauplii, whereas large larvae with BL of 12.1-14.0 mm fed on a mixture of copepod nauplii, copepodites and appendicularians from late February to April. A path analysis showed that difference in water density between 35- and 5-m depths negatively affected naupliar abundance at 10-30-m depth (standardised path coefficient beta = -0.71, p = 0.005 for 3.3-8.0-mm BL larvae and beta = -0.78, p < 0.001 for 8.1-12.0-mm BL larvae). Naupliar abundance positively affected the %GF of Ammodytes sp. larvae (beta = 0.75, p < 0.001 for 3.3-8.0-mm BL larvae and beta = 0.66, p < 0.001 for 8.1-12.0-mm BL larvae), whereas it was negatively affected by water temperature (beta = -0.45, p = 0.008 for 3.3-8.0-mm BL larvae and beta = -0.56, p = 0.002 for 8.1-12.0-mm BL larvae), and the temperature effect was weak compared with that of naupliar abundance. In turn, %GF positively affected larval somatic weight (beta = 0.91, p < 0.001 for 6.0-mm BL larvae and beta = 0.70, p = 0.005 for 10.0-mm BL larvae). The recruitment failure in 1999 was likely caused by a reduced condition factor, which resulted from low naupliar abundance. In contrast, the abundance of nauplii and Oithona similis copepodites was high in 2000 and 2001. It is possible that the higher recruitment success in 2001 was because of the higher water temperatures in Mutsu Bay, sustaining faster growth of the larvae than in 2000 under the high-prey abundance conditions.
• Use of the illicium for age determination and verification of yellow goose fish Lophius litulon off Aomori Prefecture, northern Japan

  Yuhei Takeya, Tetsuya Takatsu, Tomoyuki Yamanaka, Yasutoki Shibata, Mitsuhiro Nakaya

  NIPPON SUISAN GAKKAISHI 公益社団法人 日本水産学会 83 (1) 9 - 17 0021-5392 2017 [Refereed][Not invited]
   

  Yellow goose fish Lophius litulon is an economically valuable fish species around Japan. The aim of the present study was to evaluate a suitable technique for age determination of yellow goose fish using the illicium. Specimens of yellow goose fish were collected by commercial boats and research vessels from the Sea of Japan, Tsugaru Strait and the Pacific Ocean off Aomori Prefecture from November 2013 to March 2016 using bottom gill, set and trawl nets. Each specimen was measured and sexed, and the illicium and 8th vertebra were removed in the laboratory. The epidermis of each illicium was removed after boiling, and the illicia were dried, whereas each of the 8th vertebra was boiled and sectioned. We found that the best ageing method was a count of opaque zones in the illicia. This was facilitated using the cross-sectioned illicia that had been etched with 1 mol/L HCl for 30 s, stained with methylene blue for 4 h and viewed under transmitted and incident light. Opaque zones form twice per year ( mainly during June and November. December) in the illicia. Age determination using opaque zones in the illicia was more accurate than that using opaque zones in the vertebral centra. Because the illicia of yellow goose fish are easy to collect and manipulate for age determination and the growth rate estimated using the illicia and tagging experiments is similar, this method of age determination may be useful for these fish in this region.
• Regeneration dynamics of iron and nutrients from bay sediment into bottom water of Funka Bay, Japan

  Nanako Hioki, Kenshi Kuma, Yuichiroh Morita, Daichi Miura, Atsushi Ooki, Seiji Tanaka, Hiroji Onishi, Tetsuya Takatsu, Naoto Kobayashi, Yoshihiko Kamei

  JOURNAL OF OCEANOGRAPHY 71 (6) 703 - 714 0916-8370 2015/12 [Refereed][Not invited]
   

  We studied iron remobilization and nutrient regeneration in bottom water of Funka Bay, Japan, bimonthly from August 2010 to December 2011. The bay basin (bottom depth, 92-96 m) is separated from the northwest Pacific Ocean at its mouth by a sill with a depth of 60 m. After a spring phytoplankton bloom during early March-early April, nutrients in bay bottom water tended to accumulate with time until August-September, and to increase gradually with depth during April-October, by the oxidative decomposition of settling particulate organic matter on the bay bottom. In contrast, the process of iron remobilization into bottom water of the bay is remarkably different from nutrient regeneration. The much higher concentrations of dissolved and total dissolvable iron near the bottom and the seasonally variable relationship between dissolved iron concentration and apparent oxygen utilization in bay bottom water likely reflect a balance between dissolved iron input and removal processes within the bay bottom water. The release of soluble Fe(II) from reducing bay sediments might induce the high concentrations of dissolved and total dissolvable iron in deep-bottom waters of Funka Bay and might be one of the most important sources of iron in Funka Bay. The upward transport of iron from the bay bottom to the surface water during the winter vertical mixing may play an important role in the supply of bioavailable iron for phytoplankton growth in the coastal waters.
• Effects of hypoxia on the feeding intensity and somatic condition of the blackfin flounder Glyptocephalus stelleri in Funka Bay, Japan

  Yuta Inagaki, Tetsuya Takatsu, Takao Uenoyama, Noriko Yoneda, Shinichi Yokoyama, Yoshihiko Kamei, Naoto Kobayashi, Toyomi Takahashi

  FISHERIES SCIENCE 81 (4) 687 - 698 0919-9268 2015/07 [Refereed][Not invited]
   

  To clarify effects of hypoxia on feeding and somatic condition of blackfin flounder Glyptocephalus stelleri, we studied the temporal relationship between hypoxia and feeding intensity as well as the condition of this species in May and August 2006-2012. Hypoxia occurred near the seafloor in August between 2010 and 2012 but not in May. Population densities of gammarid amphipods Ampelisca brevicornis and Melita sp., the main prey items of blackfin flounder, were consistently low; however, the somatic condition and feeding intensity of blackfin flounder increased during hypoxia. Such an increase was not detected in May 2012 under non-hypoxic conditions. These facts imply that the hypoxia increased prey availability for blackfin flounder through the increased exposure of the gammarids over the sea floor, and, thus, resulted in improved body condition in August 2011 and 2012. Hypoxia positively would influence the somatic condition and feeding intensity of blackfin flounder in Funka Bay in August 2011 and 2012; however, the somatic condition during this period did not reach the levels recorded in 1983, suggesting that habitat quality for blackfin flounder in Funka Bay in 2011 and 2012 was worse than that in 1983.
• Annual variation in otolith increment widths of walleye pollock (Gadus chalcogrammus) larvae in Funka Bay, Hokkaido, Japan

  Yota Kano, Tetsuya Takatsu, Yutaro Hashimoto, Yuta Inagaki, Toshikuni Nakatani

  FISHERIES OCEANOGRAPHY 24 (4) 325 - 334 1054-6006 2015/07 [Refereed][Not invited]
   

  To clarify relationships between year-class strength and larval growth of walleye pollock (Gadus chalcogrammus), and oceanographic conditions in the Pacific stock off Hokkaido and Tohoku, Japan, we undertook conductivity/temperature/depth (CTD) observations and investigated larval densities, larval otolith increment widths and larval prey densities (of copepod nauplii) of the 2008, 2009, 2010 and 2011yr classes in Funka Bay. Oyashio Coastal Water (OCW) flowed into the bay in late February in 2008, 2010 and 2011, and the mean water temperatures decreased to 1.9-3.1 degrees C in March. OCW was not observed in 2009, and it was warm in late February (3.4 degrees C). Increment widths of lapillar otoliths during the yolk-sac stage were wide in 2009 and 2011, medium in 2010 and narrow in 2008. Increment widths during the first-feeding stage tended to become wider as the hatch month progressed, and the annual variation during the first-feeding stage was larger than that of the yolk-sac stage. The densities of the primary food for the larvae were high in 2008 when larval increment widths were narrowest, so the effect of prey abundance on larval growth appeared to be small. The ranking of the larval abundance in March was nearly coincident with that of the increment width during the larval stage. We, therefore, suggest that the larval growth rate is associated with the mortality rate and that the growth-mortality hypothesis may be applicable to walleye pollock in Funka Bay. Feeding success under warm water conditions may be an important factor that contributes towards high growth rates.
• Comparisons of diet and nutritional conditions in Pseudopleuronectes herzensteini juveniles between two nursery grounds off northern Hokkaido, Japan

  Yuki Kobayashi, Tetsuya Takatsu, Hiroshi Yamaguchi, Mikimasa Joh

  FISHERIES SCIENCE 81 (3) 463 - 472 0919-9268 2015/05 [Refereed][Not invited]
   

  To characterise food-habit differences in Pseudopleuronectes herzensteini juveniles we compared diets, prey diversity and nutritional states between two groups, i.e., one in the Sea of Japan and the other in the Sea of Okhotsk around northern Hokkaido, Japan. Juveniles were collected with a sledge net along the sea bottom at depths of 8-50 m in August 2010 and 2011. In the Sea of Japan, 63 were analysed (23 in 2010 and 40 in 2011). In the Sea of Okhotsk, 88 were analysed (55 in 2010 and 33 in 2011). There were no differences in standard lengths of juveniles (the Sea of Japan: 27.0 mm in 2010 in median; 28.8 mm in 2011; the Sea of Okhotsk: 28.3 mm in 2010; 29.2 mm in 2011) or in bottom water temperatures at the study sites. However, stomach content volume and Fulton's condition factor K were higher in the Sea of Okhotsk than in the Sea of Japan. High feeding intensities in the Sea of Okhotsk may have led to a higher nutritional status in fish collected from this sea. In both seas, the diet comprised mainly harpacticoid copepods, gammarids and polychaetes, with some additional bivalves being observed in the Sea of Japan. The value of the prey-diversity index (Delta*) was lower when the K value of juveniles was higher.
• Spawning migration triggers of sailfin sandfish, Arctoscopus japonicus, and the annual fluctuation of density of egg mass off Akita Prefecture

  Ryota Komoto, Tetsuya Takatsu

  Bulletin of the Akita Prefectural Institute of Fisheries 1 (1) 1 - 8 2189-3535 2015/03 [Not refereed][Not invited]
  
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• Genetic variation and population structure of marbled sole Pleuronectes yokohamae and cresthead flounder P. schrenki in Japan inferred from mitochondrial DNA analysis.

  Hideharu Tsukagoshi, Keishi Takeda, Tomoko Kariya, Takuma Ozaki, Tetsuya Takatsu, Syuiti Abe

  BIOCHEMICAL SYSTEMATICS AND ECOLOGY 58 274 - 280 0305-1978 2015/02 [Refereed][Not invited]
   

  Nucleotide sequence analysis in the first half of the mitochondrial control region was used to estimate genetic variation and population structure of marbled sole Pleuronectes yokohamae and cresthead flounder Pleuronectes schrenki, obtained from 10 localities in Japan. Overall estimate of pairwise population F-ST and NJ tree suggested genetic distinction between P. yokohamae and P. schrenki. SAMOVA also demonstrated two distinct genetic groups of the samples, MS (marbled sole, Honshu and southernmost Hokkaido) and CF(cresthead flounder, Hokkaido), which was pertinent to the natural range of P. yokohamae and P. schrenki, respectively. However, the haplotypes common to P. yokohamae and P. schrenki were found in all four samples of the CF group and two of six samples of the MS group. Haplotype and nucleotide diversities were high within MS and CF groups, and the mismatch distribution analysis showed a bimodal profile in both groups, suggesting secondary contact between allopatrically evolved MS and CF groups. Thus, the observed haplotype sharing between two species might have been the consequence of interspecific hybridization after their divergence. In addition, Psi estimates and Mantel test suggested that the population structure of P. yokohamae might have been influenced by low or restricted gene flow with isolation by distance, whereas no such population structuring was implied for P. schrenki. The observed difference in population structuring between two species was surmised by the difference of migration character. (C) 2014 Elsevier Ltd. All rights reserved.
• Inverse Estuary Circulation in Mutsu Bay-(1) Hydrographic Observations during the Summer-time-

  河野航平, 磯田豊, 工藤勲, 藤原将平, 有田駿, 小林直人, 吉田達, 扇田いずみ, 高津哲也

  海と空 海洋気象学会 90 (1) 11 - 16 0503-1567 2014/08/31 [Refereed][Not invited]
  
• Improved growth of flathead flounder Hippoglossoides dubius in hypoxic waters in Funka Bay, Japan

  Yuta Inagaki, Tetsuya Takatsu, Masafumi Kimura, Yota Kano, Toyomi Takahashi, Yoshihiko Kamei, Naoto Kobayashi, Tatsuaki Maeda

  FISHERIES SCIENCE 80 (4) 725 - 734 0919-9268 2014/07 [Refereed][Not invited]
   

  To identify the factors that influence the growth rate of flathead flounder Hippoglossoides dubius in Funka Bay, Japan, we studied temporal changes in the growth of this species and its prey from 1989 to 2012. The lowest growth rate of H. dubius was recorded in the 1995 year-class, which had experienced severe hypoxia between 1995 and 1997. However, the highest growth rate was recorded in the 2007 year-class, which had experienced hypoxia between 2009 and 2011. In 2000 and 2001, small-sized flounder (< 200 mm TL) from the 1995 year-class were feeding on mysidaceans, whereas those from other year-classes fed on small Ophiura spp. (< 9 mm in disc diameter) in 2009, 2011, and 2012. Small Ophiura spp. were more abundant in 2007 and 2011 than in 2002 and 2003. Successful recruitment of Ophiura spp. took place between 2007 and 2011 and cohorts from these years could tolerate hypoxia. This suggests that food availability improved under hypoxic conditions, which led to improved growth in small flounders. Large flounders (a parts per thousand yen200 mm TL) from all year-classes fed on prickleback fishes (Stichaeidae) and walleye pollock Gadus chalcogrammus juveniles. The growth of large flounders was enhanced by an increase in the abundance of Stichaeidae fishes and G. chalcogrammus juveniles.
• Individual variations in fatty acid composition and concentration as indicators of the nutritional condition of wild pointhead flounder larvae

  Yuko Hiraoka, Tetsuya Takatsu, Yasuhiro Ando

  MARINE BIOLOGY 161 (7) 1615 - 1625 0025-3162 2014/07 [Refereed][Not invited]
   

  We investigated the fatty acid compositions and concentrations of wild marine fish larvae with a highly accurate method because our knowledge of them has been seriously limited compared with cultured larvae. This study presents estimates of the fatty-acid-based nutritional condition of individual larvae in the field. Because the pointhead flounder Cleisthenes pinetorum displays relatively high stock size fluctuations, we investigated the developmental change in the fatty acid compositions of the body trunk, head, and eye and the annual fluctuations in the fatty acid concentrations in the trunk. We show that the process of fatty acid accumulation is not uniform across body parts and that the trunk is a better indicator of larval nutritional status than other parts because there is less time lag. Starved larvae with simultaneously high docosahexaenomic acid ratios and low total fatty acid concentrations, as observed in laboratory experiments, are rare in the wild. Thus, starved larvae must be removed rapidly by predators before they can experience a relatively long period of starvation in the wild. Fatty acid accumulation was greater in the larvae of the 2005 year class than in those of the 2006 year class in their first feeding stage, according to the optimal model derived with generalized linear model. A previous study indicated that the 2005 year class showed stronger recruitment than the 2006 year class. We conclude that the fatty acid analysis of wild larvae is a useful index of their nutritional status and mortality, especially in the first feeding stage.
• The Kyucho passing through the bay mouth of Funka Bay-(3) Numerical model experiment II-

  小林直人, 磯田豊, 高津哲也, 木村修, 亀井佳彦

  海と空 海洋気象学会 88 (3) 57 - 63 0503-1567 2013/03/22 [Refereed][Not invited]
  
• Interannual growth differences and growth-selective survival in larvae and juveniles of marbled sole Pseudopleuronectes yokohamae

  Mikimasa Joh, Mitsuhiro Nakaya, Naoto Yoshida, Tetsuya Takatsu

  MARINE ECOLOGY PROGRESS SERIES 494 267 - 279 0171-8630 2013 [Refereed][Not invited]
   

  Flatfishes drastically change their habitat, body form, and feeding during metamorphosis; thus, the early juvenile and larval stages are viewed as being critical for early survival. However, to the best of our knowledge, no studies have tested the growth-mortality hypothesis for both larval and juvenile stages of flatfishes. Therefore, we investigated the relationship between growth rate and environmental factors and tested the hypothesis for both larval and juvenile stages of marbled sole Pseudopleuronectes yokohamae in Hakodate Bay, Japan from 2001 to 2003. For both larval and juvenile stages, otolith growth correlated with water temperature. Eye-migrating larvae were defined as survivors of planktonic life (SVpelagic). Large juveniles captured in late June and July were defined as survivors of shrimp predation (SVjuvenile). To test the growth-mortality hypothesis, otolith growth was compared between the SV and the original population. During the pelagic larval stage, growth-selective survival was not detected in any of the 3 yr. During the early juvenile stage, fast-growing individuals survived selectively in 2002 but not in 2003. In 2002, population growth of juveniles was slow because water temperatures were low. Thus, juveniles in 2002 required time to exceed the size spectrum that is vulnerable to shrimp predation; consequently, the individuals that grew more rapidly were able to survive selectively. Our results show the importance of the early juvenile stage for the survival of flatfishes.
• Growth pattern of flathead flounder Hippoglossoides dubius in Funka Bay, Hokkaido, Japan

  Koudai Iwakawa, Toyomi Takahashi, Tetsuya Takatsu, Yuta Inagaki, Toshikuni Nakatani, Tatsuaki Maeda

  NIPPON SUISAN GAKKAISHI 79 (1) 10 - 19 0021-5392 2013/01 [Refereed][Not invited]
   

  The growth trajectories of flathead flounder Hippoglossoides dubius of the 1989, 1991, and 1995 dominant year-classes in Funka Bay, Hokkaido, Japan were investigated using otter trawl samples collected from 1990 to 2006. The von Bertalanffy growth model and linear equations showed good fit for the year-classes for both sexes. The observed linear increase in body length at >= 3 years old may be sustained by the dietary shift from ophiuroids and small crustaceans with low energy content to fish and decapods with high energy content. The total lengths estimated by back-calculation from the otolith increment radii obtained from older individuals were smaller than those estimated from age-length data at catch. This discrepancy is likely due to a seasonal difference in growth between body length and otoliths in H. dubius in Funka Bay, and/or to the high fishing intensity by bottom gill nets and the fact that fast-growing individuals tend to be caught at an earlier age.
• The Kyucho passing through the bay mouth of Funka Bay-(2) Numerical model experiment I-

  小林直人, 磯田豊, 高津哲也, 木村修, 亀井佳彦

  海と空 海洋気象学会 88 (2) 43 - 48 0503-1567 2012/11/30 [Refereed][Not invited]
  
• Age and growth of barfin flounder Verasper moseri in the eastern coastal waters of Cape Erimo, Hokkaido, Japan

  Yoshiya Shikishima, Tetsuya Takatsu, Toyomi Takahashi, Masamitsu Ninomiya, Shinji Sakai, Hiroyuki Ichinose, Taizo Morioka, Masayoshi Sasaki

  NIPPON SUISAN GAKKAISHI 日本水産學會 78 (6) 1170 - 1175 0021-5392 2012/11 [Refereed][Not invited]
   

  The age and growth pattern of barfin flounder Verasper moseri collected with gill nets, bottom set nets, and beam trawl nets in the eastern coastal waters of Cape Erimo, Hokkaido, Japan from April to December in 2007-2009 were examined. Numbers of individuals with an opaque edge on the blind side otolith increased in April-July but decreased in August-December. Age was determined by counting the outer margins of the transparent rings. Both males and females showed high growth rates in summer, but stagnated from November to May. Total lengths (in mm) and the ages of the fish (in years) in the catch were fitted to von Bertalanffy growth equations assuming a hatch date of April 1. Estimated equations were as follows: TLt=854.3{1-exp[-0.249(t-0.021)]} for females and TLt=518.5{1-exp[-0.512(t-0.089)]} for males. Compared to data in the literature for V. moseri from western waters, barfin flounder from the eastern waters of Cape Erimo exhibited faster growth. The summer water temperatures in the eastern waters (<= 20 degrees C) may be more suitable for rapid growth of this species.
• The Kyucho passing through the bay mouth of Funka Bay-(1) Data analysis-

  小林直人, 磯田豊, 小林雅行, 佐藤千鶴, 木村修, 山口秀一, 高津哲也, ROSA Ana Luisa

  海と空 海洋気象学会 88 (1) 9 - 20 0503-1567 2012/07 [Refereed][Not invited]
  
• Annual changes in macrobenthos abundance in Funka Bay, Japan

  Yuta Inagaki, Tetsuya Takatsu, Yuki Ashida, Toyomi Takahashi

  FISHERIES SCIENCE 78 (3) 647 - 659 0919-9268 2012/05 [Refereed][Not invited]
   

  The temporal variation in macrobenthos abundance was studied in Funka Bay in the periods 2001-2004 and 2007-2010. Dissolved oxygen just above the sea floor of the basin was lower and ignition loss at the level of the sea floor was higher in 2007-2010 than in 2001-2004. Macrobenthic species were categorized into three groups: long-lived species, sedental polychaeta , and short-lived species. Ignition loss was the most influential factor affecting macrobenthos abundance as this variable restricts the recruitment of macrobenthos. The abundance of both long-lived species and was lower between 2007 and 2010 than between 2001 and 2004. Supplementation of oxygen from outside the bay by the Tsugaru Warm Current may be an important factor impacting the increase in the abundance of long-lived species. The abundance of barely increased between 2007 and 2010, possibly because dissolved organic matter, which is their food item, may have become limited due to a narrow chink between sediments with eutrophication. The abundances of short-lived species did not differ between the periods 2001-2004 and 2007-2010 due to the organisms having a low tolerance to hypoxia. The current conditions in Funka Bay are on the verge of turning the bay into an azoic zone.
• Abundance and growth trajectory of Japanese sandfish (Arctoscopus japonicus) juveniles in Mutsu Bay, Japan

  Mitsuhiro Kudo, Tetsuya Takatsu, Shotaro Fukui, Ryota Komoto

  J. Ichthyol. 日本魚學振興會 59 (1) 21 - 35 0021-5090 2012/04/25 [Refereed][Not invited]
   

  Although spawning of Japanese sandfish (Arctoscopus japonicus) does not occur in Mutsu Bay, juveniles of the species were first discovered in the bay in June 2003 (following the initiation of yearly sampling in 1991), also being collected in subsequent years. To better understand the function of Mutsu Bay as a nursery area and the growth characteristics of the early life stages of the sandfish population, their abundance and otolith microstructure were investigated. Juveniles distributed along the sea floor in temperatures of 7.4–10.0˚C were sampled in June 2010, measuring 32.4–62.7 mm in standard length some 100–145 days after hatching, an indication of their having hatched from January 14 to February 27 (24% and 76% of juveniles hatched in January and February, respectively). June sampling surveys, conducted each year, revealed that high juvenile abundance in the bay occurred only when adult sandfish had been abundant in the Sea of Japan, off Akita and Aomori Prefectures. The origin of the juveniles in Mutsu Bay may have been the eastern Sea of Japan population, distributed off the northwestern coast of Honshu Island, the Tsushima/Tsugaru Warm Current possibly conveying the larvae and juveniles into Mutsu Bay. Median hatching dates did not differ between sampling stations in Mutsu Bay, although relatively small juveniles with narrow otolith increment widths occurred in the inner part of the bay in June 2010. Such slow-growing juveniles may have been early arrivals to Mutsu Bay from the hatching area, thereby experiencing colder water in the bay from a young age than later arrivals.
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• Vertical Distribution and Feeding Habits of Japanese Sandfish (Arctoscopus japonicus) Larvae and Juveniles off Akita Prefecture in the Sea of Japan

  Tetsuya TAKATSU

  Aquaculture Science 59 (4) 615 - 630 0371-4217 2011/12 [Refereed][Not invited]
  
• Feeding habits of two-flatfish-species larvae in Funka Bay, Japan-importance of Oikopleura as prey-

  Yutaro HASHIMOTO, Akiko MAEDA, Yusuke OHNO, Yota KANO, Tetsuya TAKATSU

  Bull. Plankton Soc. Japan 日本プランクトン学会 58 (2) 165 - 177 0387-8961 2011/08 [Refereed][Not invited]
  
• Age and Growth of Korean Flounder Glyptocephalus stelleri in Funka Bay, Hokkaido

  米田典子, 高橋豊美, 高津哲也

  水産増殖 水産増殖談話会 58 (1) 1 - 16 0371-4217 2010/03 [Refereed][Not invited]
   

  For maintaining and increasing in natural stock of Korean flounder Glyptocephalus stelleri their ages and growth in Funka Bay, Hokkaido were studied on the basis of samples caught by an otter trawl net and commercial gill nets. Observation of the otolith margin verified that annuli, outer margins of the opaque zone, were mainly produced between August and September during the birth period. Growth in both sexes was expressed by the von Bertalanffy asymptotic growth functions as SL_t = 393.1 [1-exp {-0.145 (t+0.081)}] for females and SL_t = 393.1 [1-exp {-0.134 (t+0.088)}] for males, where SL_t is standard length in mm and t is age in years. The growth rates of 1 year old and later in Funka Bay are higher than those in Japan Sea off San-in with this disparity considered to be related to food availability.
• Larval feeding intensity and year class strength of pointhead flounder Cleisthenes pinetorum in Funka Bay

  Tetsuya TAKATSU

  Bull. Jpn. Soc. Fish. Oceanogr. 73 (2) 90 - 101 0916-1562 2009/08 [Refereed][Not invited]
  
• Comparison of the nutritional transition date distributions of marbled sole larvae and juveniles in Hakodate Bay, Hokkaido

  Mikimasa Joh, Tetsuya Takatsu, Mitsuhiro Nakaya, Naoto Yoshida, Masayasu Nakagami

  FISHERIES SCIENCE 75 (3) 619 - 628 0919-9268 2009/05 [Refereed][Not invited]
   

  To examine survival processes in marbled sole Pseudopleuronectes yokohamae larvae, nutritional transition date distributions (NTDDs) were compared between larvae and large juveniles (LJs) in Hakodate Bay from 2001 to 2003. NTDDs were used instead of hatch date distributions because the onset of increment formation coincides with the timing of the transition from endogenous to exogenous nutritional sources for marbled sole. LJs were defined as being large enough to be safe from predation by the sand shrimp Crangon uritai. In 2001 and 2002, the ranges of the NTDDs of LJs largely overlapped with those of the larvae. However, in 2003, the early cohort (those whose otolith rings formed before 17 March) disappeared from the NTDDs during and after April, and the NTDDs of LJs were heavily biased toward a later period compared to those of the larvae. In 2003, Oyashio coastal water (< 3A degrees C and a parts per thousand currency sign33.0 salinity) unexpectedly intruded into the bay in late March and lowered the water temperature from 6.3A degrees C on 6 March to 4.1A degrees C on 25 March. One possible cause of mortality in the early cohort of 2003 may be feeding failure caused by the extremely low water temperature.
• The Kyucho occurred off Kameda Peninsula, Hokkaido, at the end of May, 2006

  小林直人, 磯田豊, 小林雅行, 佐藤千鶴, 木村修, 山口秀一, 高津哲也, ROSA Ana Luisa

  北海道大学水産科学研究彙報 北海道大学大学院水産科学研究院 = Research Faculty of Fisheries Sciences, Hokkaido University 58 (3) 29 - 41 1346-1842 2009/02 [Not refereed][Not invited]
   

  A large damage to fishing set-nets caused by the Kyucho occurred off Kameda peninsula on 30 May, 2006. Such Kyucho seldom occurs in this area and hence it is unusual phenomenon. Two current-meters setting off Usujiri located at Kameda peninsula and off Shiraoi faced the Hidaka Bay captured this sudden and swift current. The meteorological and oceanographical conditions in 2005 without the Kyucho and those in 2006 with the Kyucho were compared. The difference in both years was the oceanic stratification. That is, the surface halocline was thinly formed by a large quantity of rainfall water accompanied by the atmospheric disturbance on 28 May in 2006, before the Kyucho occurrence. In the case of such discontinuity subsurface thinner layer than usual, we will expect that the particle velocity of wind-induced internal Kelvin wave increases, but its phase propagation speed rather decreases. In fact, the observed surface current velocity (0.3-1.2 m/s) is almost as same as the estimated propagation speed (0.3-0.8 m/s).
• Validation of otolith increment formation and the growth rate of fat greenling larvae

  Mikimasa JOH, Takashi JOH, Teppei MATSU-URA, Tetsuya TAKATSU

  Aquacult. Sci. 水産増殖談話会 56 (2) 157 - 166 0371-4217 2008/06 [Refereed][Not invited]
   

  アイナメ飼育仔魚の耳石日周輪形成の確認と、天然仔魚の成長様式を検討した。礫石上には孵化時に明瞭な輪紋（孵化チェック）が形成された。日齢（Age）と孵化チェックの外側の輪紋数（NI）の関係は直線で示され（NI＝0.99Age－0.30、n＝49、r（2）＝0.98、P＜0.001）、傾きは1とは有意に異ならなかったことから（t検定：P＝0.31）、これらの輪紋は日周輪と判断された。陸奥湾では2003年2月から4月まで天然仔魚が表層で採集された。耳石半径と脊索長の関係はアロメトリー式で表され、バイオロジカル・インターセプト法による平均逆算体長は10日齢で9.79mm、40日齢で13.3mmと推定された。成長率は孵化直後に比較的高く（範囲：0.15-0.17mm／日）、その後次第に低下したことから、アイナメでは孵化直後の低成長期はみられないものと考えられた。
• Distribution Pattern of Demersal Fish and Food Habits of Dominant Fish Species on the Continental Slope off the Pacific Coast of Eastern Hokkaido, Japan

  山内務巨, 濱津友紀, 大村敏昭, 高津哲也, 高橋豊美

  北海道大学水産科学研究彙報 北海道大学大学院水産科学研究院 = RESEARCH FACULTY OF FISHERIES SCIENCES, HOKKAIDO UNIVERSITY 58 (1/2) 11 - 19 1346-1842 2008/05 [Not refereed][Not invited]
   

  The distribution pattern of demersal fish and food habits of the dominant fish species were studied off the Pacific coast of eastern Hokkaido during the summer of 2003-2004 and the winter of 2005. In summer, the assemblages on the upper continental slope (<400m) were primarily dominated by single species such as walleye pollock Theragra chalcogramma. The assemblages on the upper-middle slope (400-700m) were dominated by threadfin hakeling Laemonema longipes, longnose eel Synaphobranchus kaupii, and soft eelpout Bothrocara molle. The assemblage on the lower-middle slope (>700m) was dominated by macrourids(chiefly, Coryphaenoides cinereus and C.pectoralis). However, in winter, the boundary between assemblages on the middle slope was obscured slightly by the bathymetric descent of threadfin hakeling from the upper-middle slopes to the lower-middle slopes. Most dominant fish species preyed primarily on nekton, micronekton and zooplankton. However, the dominant fish species utilizing common food organisms belonged to different assemblages. This pattern of assemblage structure is characteristic of weak inter-specific competition for food and appears to be an important factor underlying increased biomass of demersal fish.
• Rapid preparation of fluorescent 9-anthrylmethyl esters for fatty acid analysis of small amount of triacylglycerols

  Yasuhiro Ando, Yusuke Haba, Kazutaka Soma, Yuko Hiraoka, Tetsuya Takatsu

  LIPIDS 42 (10) 955 - 960 0024-4201 2007/10 [Refereed][Not invited]
   

  This paper proposes a one-step method for preparation of fluorescent 9-anthrylmethyl esters from triacylglycerols (TAG) ranging in amount from 0.1 to 5 mu g. It involves base-catalyzed transesterification using potassium 9-anthracenemethoxide, prepared by proton exchange between 9-anthracenemethanol and potassium tert-butoxide. Transesterification for 10 min at room temperature gave the fatty acid 9-anthrylmethyl esters in nearly maximal yields (82-85%). The products could be analyzed by reversed-phase HPLC without purification. Excellent linear relationships were observed for standard curves of 10-250 pmol of TAG standards (16:0, 19:0, 18:2 and 22:6), and differences in the slopes were less than 5% among the standards. Almost consistent compositions of the esters were observed for the products formed from 0.5 to 5 mu g or less of fish oils TAG, and they were similar to those obtained by HPLC of ordinary multi-step synthesis products and by GLC of methyl esters. The present method is a great improvement of derivatization time, and is powerful for fatty acid analysis of small amounts of natural TAG.
• Maternal effects and larval survival of marbled sole Pseudopleuronectes yokohamae

  Tomomi Higashitani, Tetsuya Takatsu, Mitsuhiro Nakaya, Mikimasa Joh, Toyomi Takahashi

  JOURNAL OF SEA RESEARCH 58 (1) 78 - 89 1385-1101 2007/07 [Refereed][Not invited]
   

  Maternal effects of animals are the phenotypic influences of age, size, and condition of spawners on the survival and phenotypic traits of offspring. To clarify the maternal effects for marbled sole Pseudopleuronectes yokohamae, we investigated the effects of body size, nutrient condition, and growth history of adult females on egg size, larval size, and starvation tolerance, growth, and feeding ability of offspring. The fecundity of adult females was strongly dependent on body size. Path analysis revealed that the mother's total length positively affected mean egg diameter, meaning that large females spawned large eggs. In contrast, the relative growth rate of adult females negatively affected egg diameter. Egg diameters positively affected both notochord length and yolk sac volume of the larvae at hatching. Under starvation conditions, notochord length at hatching strongly and positively affected days of survival at 14 degrees C but not at 9 degrees C. Under adequate food conditions (1000 rotifers L-1), the notochord length of larvae 5 days after hatching positively affected feeding rate, implying that large larvae have high feeding ability. In addition, the mean growth rate of larvae between 0 and 15 days increased with increasing egg diameter under homogenous food conditions, suggesting that larvae hatched from large eggs might have a growth advantage for at least to 15 days after hatching. In marbled sole, these relationships (i.e., mother's body size-egg size-larval size-larval resistance to starvation-larval feeding ability) may help explain recruitment variability. (c) 2007 Elsevier B.V All rights reserved.
• Annual variation of potential predation impacts on larval and juvenile marbled sole Pseudopleuronectes yokohamae by sand shrimp Crangon uritai in Hakodate Bay, Hokkaido

  Mitsuhiro Nakaya, Tetsuya Takatsu, Mikimasa Joh, Masayasu Nakagami, Toyomi Takahashi

  FISHERIES SCIENCE 73 (1) 112 - 122 0919-9268 2007/02 [Refereed][Not invited]
   

  An investigation was conducted to evaluate the annual variation in potential predation impact (PPI) on larval and juvenile Pseudopleuronectes yokohamae by Crangon uritai in Hakodate Bay using predator-prey size relationships. Laboratory experiments were designed to estimate the favorable prey size of C. uritai through back-calculation of body length (BL) of P. yokohamae from sagittal otolith diameter observed in the stomachs of C. uritai. The most favorable prey-predator size ratio (BL of P. yokohamae-total length (TL) of C. uritai) class was 0.15-0.19, and ranged from 0.12-0.31. There was a significant positive correlation between the BL increase of P. yokohamae and the bottom water temperature in the field, such that BLs stagnated during the cold year of 1999 from April to June, and increased during the warm year of 2002. In contrast, no significant correlation was found between the TL increase of C. uritai and the bottom water temperature. Moreover, there were no significant differences in the mean TL of C. uritai between months (April-June) or years (1998-2002). Variation of PPI depended on the relationships between the growth rates of P. yokohamae and bottom water temperature. Therefore, the warm year of 2002 resulted in higher potential predation impact (PPI >= 20), and it was at least 20 days shorter than that of the cold year of 1999. These results suggest that increased bottom water temperature in the nursery area was one of the most important factors for cumulative predation loss.
• Feeding habits of stone flounder Platichthys bicoloratus larvae in Mutsu Bay, Japan

  Tetsuya Takatsu, Yuusuke Suzuki, Akiko Shimizu, Kazuo Imura, Yuko Hiraoka, Naonobu Shiga

  FISHERIES SCIENCE 73 (1) 142 - 155 0919-9268 2007/02 [Refereed][Not invited]
   

  To clarify the feeding strategy of pelagic larvae of stone flounder in Mutsu Bay, the dietary composition and prey size was investigated from February to April during 1989-1999. Diets were compared with the numerical and volumetric compositions and frequency of occurrence of each prey species. Mensuration formulae were applied to estimate individual prey volume in the diet, while the length of planktonic species was measured from net and water samples. Prey shapes were assumed as sphere, cylinder, ellipsoid, pyramid, two elliptical cones, or a combination of ellipsoid and cylinder. Prey-size range increased as the larvae grew. Preflexion larvae fed mainly on copepod nauplii. Flexion and postflexion larvae ingested primarily appendicularians, with a suggestion that these larvae might depend on some parts of the microbial food web. Low frequencies of flexion and postflexion larvae with empty guts (1.7 and 1.4%, respectively) might be derived from feeding on slow-swimming appendicularians. From a size comparison between 'house'-like organ length and trunk length of the appendicularian Oikopleura sp., almost all house-like organs with trunks in the larval diet were nonexpanded 'house rudiments', not expanded 'houses'. Thus, stone flounder larvae may not chew the houses, but swallow the house rudiments with trunks.
• Spatial distribution patterns and nutritional status of kichiji rockfish Sebastolobus macrochir in summer on the continental slope off the Pacific coast of Hokkaido, Japan

  Tetsuya TAKATSU

  NIPPON SUISAN GAKKAISHI 0021-5392 2006
• Transportation of pointhead flounder Cleisthenes pinetorum larvae in Funka Bay and its vicinity

  栗藤亜希子, 平岡優子, 高津哲也, 伊村一雄, 小林直人, 亀井佳彦

  水産海洋研究 水産海洋学会 69 (3) 145 - 155 0916-1562 2005/08 [Refereed][Not invited]
  
• Otolith microstructure and daily increment validation of marbled sole (Pseudopleuronectes yokohamae)

  M Joh, T Takatsu, M Nakaya, T Higashitani, T Takahashi

  MARINE BIOLOGY 147 (1) 59 - 69 0025-3162 2005/05 [Refereed][Not invited]
   

  We examined the daily deposition of otolith increments of marbled sole (Pseudopleuronectes yokohamae) larvae and juveniles by rearing experiments, and estimated the growth pattern of wild larvae and juveniles in Hakodate Bay (Hokkaido Island, Japan). At 16&DEG; C, prominent checks (inner checks; ca. 19.8 μ m in diameter) were observed on the centers of sagittae and lapilli extracted from 5-day-old larvae. On both otoliths, distinctive and regular increments were observed outside of the inner checks, and the slopes of regression lines between age and the number of increments (n(i)) (for sagittae: n(i)=0.98xDay-5.90; for lapillus: n(i)=0.96xDay-5.70) did not significantly differ from 1. Inner check formations were delayed at lower temperature, and the inner checks formed 13 days after hatching at 8&DEG; C. Over 80% of larvae, just after their yolk-sac has been absorbed completely (stage C), had inner checks on both their otoliths. On the lapilli, other checks (outer check) formed at the beginning of eye migration (stage G). To validate the daily deposition of increments during the juvenile stage, wild captured P. yokohamae juveniles were immersed in alizarin complexone (ALC)-seawater solutions and reared in cages set in their natural habitat. After 6 days, the mean number of rings deposited after the ALC mark was 5.7. The age-body length relationship of wild P. yokohamae larvae and juveniles caught in Hakodate Bay was divided into three phases. In the larval period, the relationship was represented by a quadratic equation (notochord length = -0.010xAge(2) + 0.682xAge-2.480, r(2)=0.82, P< 0.001), and the estimated instantaneous growth was 0.38 mm day(-1) at 15 days, 0 mm day(-1) at 34 days and -0.12 mm day(-1) at 40 days. The age-body length relationship in the early juvenile stage (< 50 days) and the late juvenile stage (> 50 days) were represented by linear equations (standard length=0.055xAge + 5.722 and standard length = 0.345xAg-9.908, respectively). These results showed that the growth rates in the late larval periods and the early juvenile stage were lower than those in the early larval stage and late juvenile stage; during the slow growth period, energy appears to be directed towards metamorphosis rather than body growth. This study provided the information needed to use otolith microstructure analysis for wild marbled sole larvae and juveniles.
• Catch efficiencies of Hirota's sledge net for crangonid shrimp and juvenile marbled sole

  N Yoshida, T Takatsu, M Nakaya, M Joh, O Kimura, S Shimizu

  NIPPON SUISAN GAKKAISHI 71 (2) 172 - 177 0021-5392 2005/03 [Refereed][Not invited]
   

  The crangonid shrimp Crangon uritai is one of the predators for marbled sole Pseudopleuronectes yokohamae juveniles in the coastal area of Hakodate Bay, Japan. The catch efficiencies of Hirota's sledge net (mouth size: 60 cm width and 40 cm height) with a distance wheel for C. uritai and P. yokohamae juveniles were obtained to estimate their accurate population densities. Assuning the catch efficiency of the drop trap (a kind of box type quadrat and 0.5 m(2) covered) to be 100%, the catch efficiency of the sledge net was 36-68% for the shrimp and increased with the shift to small body size cohort and so large female individuals disappeared. In contrast, the catch efficiency for P. yokohamae juveniles was lower than that for the shrimp and fluctuated (8-38%), which would be caused by the high escape ability of large juveniles.
• Feeding habits of pointhead flounder Cleisthenes pinetorum larvae in and near Funka Bay, Hokkaido, Japan

  Yuko Hiraoka, Tetsuya Takatsu, Akiko Kurifuji, Kazuo Imura, Toyomi Takahashi

  Bull. Jpn. Soc. Fish. Oceanogr. 水産海洋学会 = Japanese Society of Fisheries Oceanography 69 (3) 156 - 164 0388-9149 2005 [Refereed][Not invited]
   

  The feeding habits of pointhead flounder Cleisthenes pinetorum larvae were investigated in and near Funka Bay, Hokkaido Island during 10-20 August 2001. As the larvae grew, the principal prey shifted from copepod nauplii (especially, Oithona similis and Pseudocalanus newmani) as the initial food item to copepodites and an appendicularia Oikopleura sp. Nauplii of Microsetella sp. were abundant in the sampling area, but few were eaten by the larvae. The number of prey in the larval digestive tracts increased from 08:55 and peaked near sunset, suggesting the larvae are visual day feeders. Nauplii concentrations in the water varied geographically, but the number of nauplii in the larval digestive tracts did not vary. Pointhead flounder larvae in the first feeding stage might not starve in and near Funka Bay in August 2001.2001年8月10-20日の期間，北海道噴火湾とその周辺海或においてソウハチCleisthenes pnietorum仔魚の摂自生態を調査した。仔魚は成長とともに，初期飼料であるかいあし類ノープリウス（特にOithona similisとPseudcalanus newmaniからコペポダイトや尾虫類Oikopleura属の1種へと主要餌生物を移行させていた。Microsetella属の1種のノープリウスは調査海域に豊富に生息していたが，仔魚にはほとんど摂餌されていなかった。仔魚1個体が摂餌していた餌生物の平均個体数は08:55から高くなり，日没前後に最も高い値を示したことから，仔魚は視覚捕食者であることが示された。水域によってノープリウスの密度は変動していたにもかかわらず，仔魚1個体が摂餌していたノープリウスの個体数は異ならなかった。2001年夏季の噴火湾とその周辺海域において，摂餌開始期のソウハチ仔魚の飢餓による死亡の可能性は低いと考えられた。
• Food habits of kichiji rockfish Sebastolobus macrochir in summer on the continental slope off the Pacific coast of Hokkaido, Japan

  Tetsuya TAKATSU

  NIPPON SUISAN GAKKAISHI 0021-5392 2005
• Annual life cycle of adult marbled sole Pleuronectes yokohamae in the coastal waters around Kikonai Bay, Hokkaido, Japan

  M.M. Shafieipour, T. Takahashi, K. Ishino, Y. Konno, H. Nakao, M. Sano, O. Tominaga, T. Takatsu

  Aquacult. Sci. 水産増殖談話会 52 (2) 351 - 358 0371-4217 2004/12 [Refereed][Not invited]
   

  木古内湾に生息するマコガレイ成魚の生活年周期を明らかにするため、1994年5月から1996年10月までの期間、底建網と底曳網で得られた標本の生殖腺体指数（GSI）、肝臓重量指数（HSI）、肥満度（CF）、胃内容物重量指数（SCI）、空胃率の季節変化を検討した。GSIは雌雄ともに11月から増加して2月から4月にかけて著しく低下した。HSIとCFは雌雄ともに7月に最も高く、3月に最も低かった。SCIは5月に高く、11月と3月に低かった。また、空胃率は5月と7月に低く、11月と3月に高かった。以上から、本種成魚の生活年周期は産卵期（2－4月）、摂餌盛期・回復期（5－7月）、摂餌緩慢期（8－1月）の3期に区分され、さらに摂餌緩慢期は未成熟期（8－10月）と成熟期（11－1月）に分けられた。当海域はマコガレイのほぼ最北の漁場であるが、津軽暖流水の流入により冬季間も温暖なため産卵後活発に摂餌を行い、良好な栄養状態のもとで成熟を開始すると判断された。
• Quick-Offer of Current Information using T/V ADCP-Program for Quality Control of ADCP Data-

  小林直人, 磯田豊, 高津哲也, 山口秀一, 木村修

  北海道大学水産科学研究彙報 北海道大学 55 (2) 97 - 103 1346-1842 2004/10 [Not refereed][Not invited]
  
• カレイ類の年級群強度の経年変化とその要因 (総特集 動物の個体数変動様式の南北差)

  高津 哲也

  月刊海洋 海洋出版 36 (10) 761 - 765 0916-2011 2004/10 [Not refereed][Not invited]
  
• Effects of hypoxia on principal prey and growth of flathead flounder Hippoglossoides dubius in Funka Bay, Japan

  M Kimura, T Takahashi, T Takatsu, T Nakatani, T Maeda

  FISHERIES SCIENCE 70 (4) 537 - 545 0919-9268 2004/08 [Refereed][Not invited]
   

  Effects of hypoxia on the principal prey and growth of flathead flounder Hippoglossoides dubius were studied in Funka Bay. Of the three dominant year-classes that occurred in recent years, the 1995 year-class was small in total length at age greater than or equal to3 and low in condition factor at age greater than or equal to2. Ophiuroids (almost Ophiura sarsi), which were the dominant prey in the 1980s, were of little importance and instead. crustaceans such as mysids, natant decapods and pelagic amphipods, bivalves and fish were important prey items for H. dubius in 2000-2001. In addition, the feeding intensity of H. dubius in 2000-2001 was lower than that in the 1980s. These facts are closely related to a reduction of prey abundance, particularly ophiuroids. It seems that the hypoxia that occurred in the central part of the bay during the summer and autumn of 1995-1997 caused the poor food supply and low growth race a ages 2-4 of the 1995 year-class.
• Spatial distribution and feeding habits of the shrimp Crangon uritai as a predator on larval and juvenile marbled sole Pleuronectes yokohamae

  Mitsuhiro Nakaya, Tetsuya Takatsu, Masayasu Nakagami, Mikimasa Joh, Toyomi Takahashi

  Fisheries Science 70 (3) 445 - 455 0919-9268 2004/06 [Refereed][Not invited]
   

  To examine predation on larval and juvenile Pleuronectes yokohamae by Crangon uritai, the spatial distribution and feeding habits of C. uritai were studied. Crangon uritai fed on various prey, including P. yokohamae. Density-dependent predation on juvenile Crangon spp., larval and juvenile gobiid fish Chaenogobius heptacanthus, mysids, and gammarids was observed. The abundance of alternative prey might, therefore, play an important role in reducing the pressure of predation on P. yokohamae. In each year, C. uritai migrated from depths of 10 m in March to depths of 3 m in May. There was a significant negative correlation between the weighted mean depth (WMD) of C. uritai and the weighted mean bottom water temperature (WMBWT). The migration was, therefore, delayed in the cold spring, during which C. uritai occupied depths of approximately 10 m. In contrast, no significant correlation was found between the WMD of P. yokohamae and WMBWT. Settlement of P. yokohamae began at depths of 15 m, mainly during early April. The spatial distributions of these two organisms show greater overlap during the cold spring, resulting in increased opportunities for predation.
• Spatial distribution of brown sole Pseudopleuronectes herzensteini eggs and larvae in Mutsu Bay, Japan

  K Imura, T Takatsu, N Nanjo, O Kimura, T Takahashi

  NIPPON SUISAN GAKKAISHI 70 (1) 39 - 47 0021-5392 2004/01 [Refereed][Not invited]
   

  The spatial distribution of brown sole Pseudopleuronectes herzensteini eggs and larvae, and their food organisms were examined to elucidate the early life history of this species in Mutsu Bay. In April 1990-1997, pelagic larvae were widely distributed in the bay. Vertical distributions of eggs and larvae were investigated at two sampling stations in the bay from late February to late June in 1999-2001. Eggs of early, middle, and late stages occurred mainly in 30-40, 10-20, and 1-20 m layers, respectively. Yolk-sac larvae (stages A-B) occurred chiefly in the 20-40 m layer. The layer of abundant preflexion larvae (stages C-D) was slightly deeper (mainly 20 m depth) than that of copepod nauplii (10-20 m layer) as larval initial food. Larval concentration at 20 in depth may play some role in avoiding transportation to a shallow area unsuitable for settlement. Because the weighted-mean-depths of relatively larger larvae (flexion or postflexion larvae, stages E-G) were deeper (greater than or equal to24 m) than those of stages C-D larvae (20-22 m), larvae would ontogenetically migrate for settlement.
• Prey Choice Order of Crangon uritai as a Predator for Juvenile Pleuronectes yokohamae

  NAKAYA Mitsuhiro, TAKATSU Tetsuya, NAKAGAMI Masayasu, JOH Mikimasa, TAKAHASHI Toyomi

  Aquacult. Sci. 日本水産増殖学会 52 (2) 121 - 128 0371-4217 2004 [Refereed][Not invited]
   

  During the spring in the coastal waters of Hakodate Bay the shrimp <I>Crangon uritai</I> is the predominant predator on larval and juvenile marbled sole, <I>Pleuronectes yokohamae</I>. To investigate the prey preferences of <I>C. uritai, P. yokohamae</I> and two other prey species, a mysid <I>Nipponomysis</I> sp. and a gammarid <I>Haustorioides japonicas</I>, were used for predation experiments. Among the three prey organisms studied, <I>Nipponomysis</I> sp. was preyed on first, followed by <I>P. yokohamae</I>, and finally <I>H. japonicas</I>. Prey profitability did not differ between <I>P. yokohamae</I> and <I>Nipponomysis</I> sp., though <I>H. japonicas</I> was less profitable. <I>Nipponomysis</I> sp. was larger, more perceptible, and slower to escape than <I>P. yokohamae</I>. A relatively high abundance of mysid <I>Nipponomysis</I> sp. could restrict and reduce predation on <I>P. yokohamae</I> by <I>C. uritai</I>. Gammarid <I>H, japonicas</I> was able to escape relatively more easily, because its harder and slippery skin required more handling time than the other prey, possibly making it an undesirable food source for <I>C. uritai</I>. High perceptibility and low escape ability may be the most important factors affecting prey choice of <I>C. uritai</I>.
• Feeding habits of Japanese flounder Paralichthys olivaceus larvae in Mutsu Bay, Northern Japan

  A Hasegawa, T Takatsu, K Imura, N Nanjo, T Takahashi

  NIPPON SUISAN GAKKAISHI The Japanese Society of Fisheries Science 69 (6) 940 - 947 0021-5392 2003/11 [Refereed][Not invited]
   

  The feeding habits of Japanese flounder Paralichthys olivaceus larvae were investigated in Mutsu Bay, northern Japan. Larvae were collected by horizontal hauls with a plankton net (80 cm diameter and 0.35 mm mesh aperture) or MTD nets (56 cm diameter and 0.35 mm mesh aperture) at two stations in the bay from June 15 to June 29, in 1999 and May 30 to June 28, in 2001. At the first feeding stage, larvae fed mainly on tintinids, Undella sp., copepod nauplii, mainly Paracalanus sp., and Oikopleura sp. Food items for larger larvae were Oikopleura sp. and copepodites. The larvae with nauplii in the diet at the first feeding stage were more frequently found in 2001 (55%) than in 1999 (16%). In the environment, the abundance in the biovolume of Paracalanus nauplii in 2001 was about 1.2-2.0 times larger than that in 1999. Allometric growth curves between notochord length and body weight show that larvae were plumper in 2001 than those in 1999. Therefore, the feeding intensity and the somatic condition of larval Japanese flounder at the initial feeding stage would be vulnerable to change in naupliar abundance in the environment.
• フォルマリンとエタノール固定によるマコガレイ仔魚の体長収縮

  城 幹昌, 高津 哲也, 中屋 光裕, ほか

  水産増殖 水産増殖談話会 51 (2) 227 - 228 0371-4217 2003/06 [Refereed][Not invited]
   

  ホルムアルデヒド、エタノール、カレイ類、保存、体長、収縮。
• Age and growth of Sebastes vulpes in the coastal waters of western Hokkaido, Japan

  T Sekigawa, T Takahashi, T Takatsu, S Nishiuchi, M Sasaki, F Shiokawa

  FISHERIES SCIENCE 69 (3) 575 - 580 0919-9268 2003/06 [Refereed][Not invited]
   

  Age and growth of Sebastes vulpes collected from the coastal waters of western Hokkaido were studied. Observation of the otolith margin verified that annuli (outer margins of the opaque zone) were produced chiefly from July to August. This period was associated with parturition and the birth season. The maximum age estimated by the surface method was 12 years but the oldest fish was aged at 35 years by the cross-section method. The surface method was inadequate for aging of S. vulpes older than 6 years because of the underestimation of age. No significant difference was found in the parameters of the growth equations between both sexes. The von Bertalanffy growth curve combined for both sexes was as follows: SLt = 358.6(l - exp(-0.156(t+0.820))), where SLt is standard length (mm) at age t (after parturition in years). It seems likely that S. vulpes grows slowly and lives longer than previously thought.
• Maturation of fat greenling Hexagrammos otakii females in Kikonai Bay, Hokkaido

  T Sekigawa, T Takahashi, T Takatsu, Y Sakurai

  NIPPON SUISAN GAKKAISHI 69 (3) 380 - 386 0021-5392 2003/05 [Refereed][Not invited]
   

  To clarify the maturation process of female fat greenling Hexagranimos otakii, histological observations were carried out on the ovaries of samples collected in Kikonai Bay, southern Hokkaido, from June 1999 to May 2000. The maturation process within the size range examined (170-460 mm in standard length) was divided into 6 phases: immature (recovery), oil droplet, yolk formation, maturation, spawning, and spent. Based on changes of the development stage and diameter of oocytes, the development form of fat greenling was thought to belong to the "group-synchronous oocyte development" type. The spawning season in this region was assumed to occur from November to January, with a peak occurring between mid-November and late December.
• Environmental Factors in Funka Bay, Hokkaido, Affecting the Year Class Strength of Walleye Pollock, Theragra chalcogramma

  NAKATANI Toshikuni, SUGIMOTO Koichi, TAKATSU Tetsuya, TAKAHASHI Toyomi

  Bulletin of the Japanese Society of Fisheries Oceanography 水産海洋学会 67 (1) 23 - 28 0388-9149 2003/02 [Refereed][Not invited]
   

  磯田ほかは、1974年から1994年までの噴火湾周辺の水温の経年変化を調べ、1980年級群が卓越年級群となった原因として、冬季間の高水温と北西風による湾内への卵輸送が多かったことを挙げている。本報告では、卓越年級群が発生した1995年を含め、1991年から1998年までに調査された噴火湾における冬季の仔魚の分布密度、摂餌開始期仔魚の餌生物環境および水温環境を比較し、当海域におけるスケトウダラの卓越年級群の発生機構について再検討した。
• Age and Growth of Fat Greenling Hexagrammos otakii in Kikonai Bay, Hokkaido.

  Takeshi SEKIGAWA, Toyomi TAKAHASHI, Testuya TAKATSU

  Aquacult. Sci. 水産増殖談話会 50 (4) 395 - 400 0371-4217 2002/12 [Refereed][Not invited]
   

  アイナメは日本各地、朝鮮半島南部および黄海に分布し、沿岸漁業の重要な対象種となっている。アイナメの年齢と成長に関しては、これまでに陸奥湾、岩手県沿岸、仙台湾、福島県沿岸、常磐北部海域、三河湾・伊勢湾などから報告があるが、北海道沿岸における集団については報告がない。本種の年齢査定は、1940年代には、脊椎骨、山本・西岡では鱗が用いられ、その後小林らでは耳石の横断面薄片法、福島県では耳石の表面観察法により行われている。アイナメが属するカサゴ目のアラスカメヌケ、カサゴ、ギンダラなどでは、高齢魚になると表面観察法は年齢を過少評価しがちであり、横断面薄片法が適切であることが指摘されている。したがって、アイナメについても上述2法の年齢査定法としての妥当性を調べる必要がある。そこで本報では、北海道木古内湾に生息するアイナメについて、耳石を用いた年齢査定を表面観察法と横断面薄片法（以下、それぞれ表面法および横断面法という）で行い、本種の年齢査定法を吟味した上で、当海域における年齢と成長の関係を解析するとともに海域間の比較を行い、成長に影響を及ぼす要因について考察した。
• Possible causes of annual change in the year class strength of flathead flounder Hippoglossoides dubius (Pisces, Pleuronectiformes) in Funka Bay, Hokkaido

  T. Nakatani, T. Maeda, K. Sugimoto, T. Takatsu, T. Takahashi

  Bull. Jpn. Soc. Fish. Oceanogr. 66 (4) 216 - 223 2002/12 [Refereed][Not invited]
  
• Energy content of the mysid Neomysis czerniawskii in Iwanai Bay, the coastal water of western Hokkaido

  K Kooka, D Yanagida, Y Suzuki, S Ohsaki, T Takatsu

  FISHERIES SCIENCE 68 (4) 951 - 953 0919-9268 2002/08 [Refereed][Not invited]
  
• Spatial distribution and feeding habits of Pacific cod (Gadus macrocephalus) larvae in Mutsu Bay, Japan

  T Takatsu, T Nakatani, T Miyamoto, K Kooka, T Takahashi

  FISHERIES OCEANOGRAPHY 11 (2) 90 - 101 1054-6006 2002/03 [Refereed][Not invited]
   

  The spatial distributions and feeding habits of Pacific cod (Gadus macrocephalus) larvae, and the spatial distributions of copepod nauplii and copepodites, their main prey, were examined in Mutsu Bay from February to March during 1989-92. Yolk-sac larvae were caught at 30-45 m depth at the bay Mouth. Larvae without yolk were collected at 8-45 m depth at the bay mouth and the inner part of the bay, and large larvae were chiefly found in the bay. This geographical pattern in larval size may have been because of transport to the inner part of Mutsu Bay by the Tsugaru Warm Cur, rent. The dominant taxa of copepod nauplii and copepodites in the diet and the environment changed each year. Larvae fed mainly on abundant taxa in the environment, suggesting that larvae are opportunistic feeders. Nauplii and copepodites were abundant in the bay, especially in 1992. Copepodites were slightly more abundant in the diet of cod larvae in 1992 than in 1991, but this difference was smaller than in the environment. In addition, larvae with empty digestive tracts were scarce in 1991 and 1992. Prey concentrations in the bay in 1991 and 1992 seem to have been high enough to sustain most Pacific cod larvae.
• Spatial and Temporal Distribution of Larval and Juvenile Marbled Sole Pleuronectes yokohamae in Hakodate Bay.

  Masayasu NAKAGAMI, Tetsuya TAKATSU, Mitsuhiro NAKAYA, Toyomi TAKAHASHI

  Bull. Jpn. Soc. Fish. Oceanogr. 65 (3) 85 - 93 0916-1562 2001/08 [Refereed][Not invited]
  
• The juvenile cresthead flounder (Pleuronectes schrenki): An occasional cleaner occurring in Lake Notoro, Hokkaido

  J.-S. Ho, K. Nagasawa, T. Takatsu

  Bull. Fish. Sci. Hokkaido Univ. 北海道大学 52 (1) 1 - 3 1346-1842 2001/03 [Not refereed][Not invited]
  
• Spatial and temporal distribution of Pacific cod Gadus macrocephalus juveniles in Mutsu Bay

  T. Takatsu, Y. Yoshida, K. Kooka, K. Sugimoto, T. Takahashi

  Bull. Jpn. Soc. Fish. Oceanogr. 水産海洋学会 = Japanese Society of Fisheries Oceanography 65 (1) 6 - 14 0388-9149 2001/02 [Refereed][Not invited]
   

  The spatial distributions of Pacific cod (Gadus macrocephalus) juveniles and their food organisms were examined in Mutsu Bay from April to July during 1988-1997. In April, large larvae (≤25 mm in total length (TL)) and pelagic juveniles (>25 mm TL) were widely distributed in the bay, and were concentrated at the same depths as calanoid copepodites during daylight hours. Geographical changes in cod TLs might have been due to transport by the Tsugaru Warm Current. After mid- and late May, juveniles and calanoid copepodites occurred on the bottom. Mean densities of cod juveniles fluctuated annually in April and June, and high densities occurred when calanoid copepods were abundant. Juveniles were rarely found at temperatures >12℃, and it is likely that they migrate out of the bay after late June when temperatures increase and the abundance of prey decrease in the bay. Pacific cod use Mutsu Bay as a nursery ground, and calanoid copepodites sustain cod larvae and juveniles as their prey until mid-June. Large fluctuation in mortality of Pacific cod might occur in pelagic juvenile and subsequent stages after April in Mutsu Bay.1988-1997年4-7月に，陸奥湾においてマダラ稚魚とその餌生物の時空間分布を調べた．4月には大型仔魚（全長25mm以下）と浮遊稚魚（>25mm）は湾内に広く分布し，昼間はカラヌス目かいあし頬の高密度分布層に集中した．仔稚魚の体サイズの地理的変異は，津軽暖流水による輸送により生じたものと推定された．5月中下旬以降稚魚とカラヌス目は海底直上に出現した．4月と6月の稚魚の平均個体数密度は年によって大きく変動し，稚魚高い個体数密度はカラヌス目の高い豊度とともにみられた．湾内の水温上昇と餌豊度が低下する6月下旬以降，稚魚は水温12℃を超える水域にほとんど出現せず，湾外に移動すると考えられた．マダラは陸奥湾を生育場として利用し，カラヌス目コペポダイトは6月中旬まで仔稚魚の餌生物として生残を支える．陸奥湾におけるマダラ仔稚魚の死亡率の変動は，主に4月の浮遊稚魚期以降に生じたものと思われる．
• Age and growth of marbled sole (Pleuronectes yokohamae) in the coast waters of western Aomori Prefecture, Japan

  Tetsuya TAKATSU

  Bull. Fac. Fish. Hokkaido Univ. 51 (2) 51 - 56 2000/09 [Not refereed][Not invited]
  
• Feeding on harpacticoid copepods by marbled sole Pleuronectes yokohamae juveniles in the Coastal Ares of Tsugaru Strait, Hokkaido

  M Nakagami, T Takatsu, T Matsuda, T Takahashi

  NIPPON SUISAN GAKKAISHI The Japanese Society of Fisheries Science 66 (5) 818 - 824 0021-5392 2000/09 [Refereed][Not invited]
   

  Monthly changes in the main food items of and biased feeding on adult males of harpacticoid copepods by marbled sole Pleuronectes yokohamae juveniles were examined in the Coastal Area of Tsugaru Strait, Hokkaido, from April to September 1996 and in May 1997. At Iwabe Fishing Port in May-July 1996 and May 1997, marbled sole juveniles (less than or equal to 30 mm in SL) fed on harpacticoid copepods, mainly Harpacticus sp. Off Nanaehama Beach in May 1997, juveniles preyed on harpacticoids, mainly Haledinosoma sp. In August, the main food organisms of juveniles (>30 mm in SL) changed from harpacticoids to small benthic crustaceans and polychaetes. Tn September 1996, juveniles fed chiefly on polychaetes. Adult males of Harpacticus sp. and Halectinosoma sp. were found in significantly larger numbers than adult females and copepodites (stage I-V) in fish stomachs. Tn contrast, no significant difference was found in the sex ratio of Harpacticus sp. on the bottom sediment at Iwabe. Because adult female harpacticoids in the stomachs of juveniles had larger body widths than adult males and copepodites, the biased feeding on adult males can not be explained by differences in prey size. The specific feeding by marbled sole juveniles might have been caused by a behavioral difference between harpacticoid males and females in their breeding season.
• Occurrence periods and food habits of cresthead flounder Pleuronectes schrenki juveniles in Lake Notoro, Hokkaido

  T. Takatsu, S. Takagi, S. Yokoyama, T. Takahashi

  Bull. Fac. Fish. Hokkaido Univ. 50 (3) 155 - 169 1999/09 [Not refereed][Not invited]
  
• Year group variation of small-mouthed sole and Pacific cod in Mutsu Bay.

  高津哲也, 小岡孝治

  東北底魚研究 19 92 - 95 1999/07 [Not refereed][Not invited]
  
• Distribution and maturation of adult walleye pollock in autumn in the Japan Sea off southwest Hokkaido

  Y Kamei, T Takatsu, S Takagi, T Nakatani, T Takahashi, T Maeda

  NIPPON SUISAN GAKKAISHI 65 (2) 223 - 229 0021-5392 1999/03 [Refereed][Not invited]
   

  In order to elucidate the association between the distribution and maturation of adult walleye pollock Theragra chalcogramma, otter trawl samplings were carried out in the Japan Sea off the southwest Hokkaido in October from 1989 to 1994, CPUE values of walleye pollock were significantly higher in the coastal region than those in the offshore region through the sampling years except for 1994. Proportions of males were significantly higher in the coastal region except for 1993 and 1994, Many males were nearly mature, and no differences in male gonad indices were found either between coastal and offshore regions or among the coastal areas. In contrast, females collected in the coastal region were more mature than those in the offshore region. Clear geographical differences in body length were not found either among males or among females. Sexual differences in reproductive behavior and maturity might be responsible for the skewed distribution pattern of adult walleye pollock in October.
• Age and growth of marbled sole Pleuronectes yokohamae in Kikonai Bay, Hokkaido, Japan

  M. M. Shafieipour, T. Takahashi, K. Ishino, T. Takatsu, T. Nakatani

  Iranian Journal of Fisheries Science 1 (1) 5 - 21 1999 [Refereed][Not invited]
  
• Vertical distribution and prey of walleye pollock in the northern Japan Sea

  K Kooka, T Takatsu, Y Kamei, T Nakatani, T Takahashi

  FISHERIES SCIENCE 64 (5) 686 - 693 0919-9268 1998/10 [Refereed][Not invited]
   

  Vertical distributions of adult walleye pollock Theragra chalcogramma and oceanographic conditions were examined in the northern Japan Sea. In the daytime, most walleye pollock were distributed from 150 to 250 m depth in April and from 400 to 500 m depth in October. Between 150 and 500 m depth, temperatures in October (0.4-8.8 degrees C) were similar to those in April (0.5-5.4 degrees C), salinity levels were fairly uniform in both months (34.0-34.2 PSU), and dissolved oxygen concentrations were 4.6-6.1 ml/l in April and 4.7-6.4 ml/l in October. The main foods of walleye pollock in April were the amphipod Themisto japonica, the euphausiid Thysanoessa longipes, and the chaetognath Sagitta elegans. Daytime weighted mean depths of T. longipes were significantly greater in October than in April. Biomass of T. longipes in the habitat of walleye pollock was significantly greater than other layers in both months. The seasonal change in vertical distribution of walleye pollock is presumably related to food availability of T. longipes.
• Food habits of walleye pollock inhabiting the mesopelagic zone in the northern Japan Sea in spring and autumn

  K Kooka, T Takatsu, Y Kamei, T Nakatani, T Takahashi

  NIPPON SUISAN GAKKAISHI 63 (4) 537 - 541 0021-5392 1997/07 [Refereed][Not invited]
   

  The diet and feeding intensity of walleye pollock Theragra chalcogramma were investigated in April and October 1993, and in April 1994. Specimens ranging from 262 to 456 mm in standard length were sampled with a mid-water trawl off Hiyama Subprefecture and Aomori Prefecture in the northern Japan Sea. The main food items were large-sized zooplankton. In April, pollock fed chiefly on euphausiids (Thysanoessa longipes), chaetognaths, and hyperiid amphipods (Themisto japonica). In October, the main food organisms were hyperiid amphipods (T. japonica). Stomach-content weight indices indicated that the feeding intensity of pollock was stronger in April (after spawning) than in October (before spawning). The numerical compositions of food categories in April differed among sampling stations. Such differences were not observed in October. It seems likely that the distinct variation of diets in April is ascribed to geographic differences in zooplankton composition in the mesopelagic zone.
• Gonadal maturation of female rainbow smelt Osmerus eperlanus mordax in Funka Bay, Hokkaido

  K Inokuchi, T Nakatani, T Takatsu, T Takahashi

  NIPPON SUISAN GAKKAISHI 63 (1) 50 - 55 0021-5392 1997/01 [Refereed][Not invited]
   

  Rainbow smelt Osmerus eperlanus mordax, vc ere collected during May 1993 to April 1995 from Funka Bay, Hokkaido, and the Yamazaki and Rukotsu rivers, which flow into the western side of the bay. Ovarian eggs from females were examined histologically. Oocytes from the chromatin-nucleolus stage to the ripe stage were found in the ovaries. From May to August, females had immature oocytes in the yolkless stage and yolk vesicle stage. Postovulatory follicles were also found in the ovaries of females collected from the bay in May. After November, a bimodal distribution of egg diameter was observed. More advanced oocytes developed from the primary-yolk stage in November to the migratory-nucleus stage in April. These observations indicate that group-synchronous oocyte development occurred. All oocytes in the migratory-nucleus stage from females collected by set nets in the coastal area off Mori were found in late April. From late April to mid-May, oocytes of females collected from the two rivers were in the ripe stage. These results suggest that rainbow smelt inhabiting Funka Bay spawn from late April to mid-May in the rivers flowing into the western coast of the bay. Visual observations of adults in the rivers and the developmental process of oocytes indicate that rainbow smelt return to the sea after spawning.
• Distribution of walleye pollock Theragra chalcogramma off southwestern Hokkaido in the Japan Sea in spring

  S Takagi, T Maeda, Y Kamei, T Nakatani, T Takatsu, T Takahashi

  NIPPON SUISAN GAKKAISHI 62 (2) 205 - 212 0021-5392 1996/03 [Refereed][Not invited]
   

  In order to elucidate the distribution pattern of walleye pollock Theragra chalcogramma off southwestern Hokkaido in the Japan Sea, trawling and acoustic surveys, and hydrographic observations were conducted in early April from 1989 to 1993, In 1991 and 1993, the Tsushima Warm Current Water was widely distributed in the coastal area of Aomori Prefecture, and a large number of walleye pollock were collected in the southwestern area off Hokkaido. In contrast, this water was observed only in a restricted coastal area of Aomori Prefecture in 1989 and 1990, and walleye pollock were found distributed in a coastal area 20-30 miles off Aomori Prefecture. Although an annual change in the distribution of walleye pollock was observed, they were concentrated in the area of the horizontal thermal front between the Tsushima Warm Current Water and the Japan Sea Proper Water every year. From these observations, it appears that the migration of walleye pollock. in early spring is closely related to the behavior of the Tsushima Warm Current Water in the Japan Sea off Aomori Prefecture.
• Age and growth of brown sole Pleuronectes herzensteini in the coastal waters of western Aomori Prefecture, Japan

  T Takahashi, Y Hayakawa, T Kamiharako, T Nakatani, T Takatsu

  FISHERIES SCIENCE 61 (6) 893 - 897 0919-9268 1995/12 [Refereed][Not invited]
   

  Age and growth of brown sole Pleuronectes herzensteini collected from the coastal waters of western Aomori Prefecture from September 1989 to September 1990 were determined from otolith analysis. Observation of the otolith margin verified that annuli (outer margins of the translucent zone) were mainly produced between February and March. This period was associated with the spawning season. Growth of brown sole was expressed by the von Bertalanffy asymptotic growth function as TL(t) = 255.2(1 - exp(-0.463(t-0.267))) for males and TL(t)= 350.2(1 - exp(-0.308(t-0.300))) for females, where TL(t) is the total length in mm and t is age in years. It was found that the growth rate of brown sole in this study area is very high as compared with the more southern population in the Niigata region. In the northern Japan Sea, there is a tendency that the growth rate in the north is higher in length at comparable ages. It is possible that the growth of brown sole in the northern Japan Sea is closely related with bottom water temperature.
• GONADAL MATURATION OF FEMALE RIBBON PRICKLEBACK IN FUNKA-BAY, HOKKAIDO

  H TSUTSUI, T NAKATANI, T TAKATSU, T TAKAHASHI

  NIPPON SUISAN GAKKAISHI 日本水産學會 61 (5) 707 - 712 0021-5392 1995/09 [Refereed][Not invited]
   

  Gonadal maturation of female ribbon prickleback, Lunzpenus sagitta, collected in Funka Bay, Hokkaido, from September 1991 to Mayebruary 1994 was examined histologically. Oocytes from the chromatin nucleolus stage to the migratory nucleus stage were observed in the ovary/ Based on the developmental stages of ovarian eggs, the maturity of female of L. sagitta was divided into five stages: the yolk vesicle stage, the oil drop stage, the early yolk formation stage, the late yolk formation stage and the migratory nucleus stage. In January, 91.5% of the femals had oocytes at the yolk vesicle stage and 8.4% at the oil drop stage. In the same period, postovulatory follicles were found in the ovary. Percentages of oocytes at the oil drop stage increased to 80% in May. In the middle of September, all of the females were in the late yolk formation stage. In November, many oocytes at the migratory nucleus stage were observed. These observations, indicate that L. sagitta spawn from December to January in Funka Bay.
• FEEDING-HABITS OF PACIFIC COD LARVAE AND JUVENILES IN MUTSU BAY, JAPAN

  T TAKATSU, T NAKATANI, T MUTOH, T TAKAHASHI

  FISHERIES SCIENCE 61 (3) 415 - 422 0919-9268 1995/06 [Refereed][Not invited]
   

  The diets and prey widths of Pacific cod (Gadus macrocephalus) larvae and juveniles were examined in Mutsu Bay. In early March, 11 yolk-sac larvae were caught in midwater of the bay mouth. Five of 11 larvae captured had not opened their mouths, and the remaining six had not fed. Post-larvae less than or equal to 7 mm in total length (TL) fed on copepod nauplii, particularly Pseudocalanus nauplii. Prey items of post-larvae >7 mm TL were chiefly crustacean eggs, and Pseudocalanus spp. copepodites and adults. From April to June, the main food organisms of cod juveniles were calanoid copepods, and changed from Pseudocalanus spp. to Calanus pacificus, Acartia clausi, and Centropages abdominalis. In addition, cod juveniles opportunistically fed on large-sized food organisms, namely, reptant megalopae, planktonic gastropods, and natant zoeae. In July, cod juveniles mainly fed on benthic prey items, such as gammarid amphipods and fish. It seems probable that these large-sized food organisms play an important role as alternative prey for cod juveniles when they change their main food from calanoid copepods to benthic prey items.
• Distribution and food habits of eggs and larvae of Hippoglissoides dubius in Funka Bay and its offshore waters, Hokkaido

  Tetsuya TAKATSU

  Bull. Jpn. Soc. Fish. Oceanogr. 水産海洋学会 = Japanese Society of Fisheries Oceanography 57 (1) 1 - 14 0916-1562 1993/02 [Refereed][Not invited]
   

  Eggs, larvae, and juveniles of Hippoglossoides dubius were collected in Funka Bay and vicinity, Hokkaido, in 1989 and 1990. Distributions of the eggs of early developmental stages showed that the eggs ware spawned in the inner area of the bay. Before the exhaustion of their yolk, larvae initiated feeding on copepod nauplii, diatom, and invertebrate eggs. The proportion of copepod nauplii in the stomachs increased with growth. Juveniles fed on large sized plankton such as copepodids, larval euphausiids, and appendicularia. Copepod nauplii, the principal food for the larvae at the early developmental stages, increased in the bay after the invasion of the Oyashio Water. It is inferred that the mortality of Hippoglossoides dubius during the early life stages would be closely related of the movement of the Oyashio Water.
• DISTRIBUTION AND MOVEMENT OF WALLEYE POLLOCK IN EARLY LIFE STAGES IN MUTSU BAY, AOMORI

  T TAKATSU, T TAKAHASHI, T NAKATANI, T MAEDA, K OHKOSHI

  NIPPON SUISAN GAKKAISHI 日本水産學會 58 (12) 2235 - 2243 0021-5392 1992/12 [Refereed][Not invited]
   

  Distribution and movement of walleye pollock Theragra chalcogramma eggs, larvae, and juveniles were investigated in Mutsu Bay from February to July in 1989 and 1990. During February and March, eggs and larvae were mostly found in the mouth part of the bay. In April, larvae and juveniles were widely distributed in the bay, where the water temperature ranged from 7.5 to 10.1-degrees-C and their main food organisms, particularly Pseudocalanus spp., were abundant in the same area. In this period, large-sized juveniles were mainly collected near the bottom in the eastern part of the bay, whereas larvae and small-sized juveniles were concentrated in the shallow waters near the mouth part of the bay. In May, the water temperature at the surface rose to 10.9-12.7-degrees-C and most of the juveniles moved to the bottom of the western and mouth part of the bay. After June, it seems probable that juveniles began to migrate outside of the bay, because of high water temperature and a lack of food organisms in the bay.
• Spawning and Growth of Macrura Argis lar in Funka Bay and offshore, Hokkaido.

  武藤卓志, 前田辰昭, 中谷敏邦, 高津哲也, 松島寛治, 高橋豊美

  水産海洋研究 水産海洋学会 = Japanese Society of Fisheries Oceanography 56 (4) 426 - 432 0916-1562 1992/12 [Refereed][Not invited]
   

  Argis lar (Decapoda, Caridea) were collected by experimental bottom trawls in Funka Bay and offshore (less than 200m depths) from May 1987 to September 1989. More than 85% of them were adult female. The seasonal changes in gonadosomatic index, the occurrence of the ovigerous female, and carapace length composition suggested that most of A. lar spawned at the age of 30 months, and spawning and hatching period were August to September and February to March, respectively. The regressions of body weight (BW:g) and body length (BL:mm) on carapace length (CL:mm) were calculated as follows; CL-BW: BW=0.00077CL^2.947 (r=0.98) CL-BL: BL=3.357CL+7.858 (r=0.98)

MISC

• スケトウダラ太平洋系群における卵から前屈曲期仔魚にかけた母親効果の継続性の検討

  金谷彩友美, 中屋光裕, 髙津哲也  水産海洋研究  88-  (2)  80  -81  2024/05  [Not refereed]
  
• 太平洋系群の産卵前経験水温と再生産成功率の関係

  髙津哲也, 山村織生, 境 磨, 金谷彩友美, 中屋光裕  水産海洋研究  88-  (2)  78  -79  2024/05  [Not refereed][Not invited]
  
• 噴火湾の底生魚類が捕食するスケトウダラ稚魚の特徴

  髙津哲也, 納谷晃弘, 柳澤和彦, 中屋光裕  水産海洋研究  85-  (3)  181  -182  2021/09  [Not refereed][Not invited]
  
• キアンコウ仔魚の卵帯からのふ出に関する研究

  石川智也, 中屋光裕, 高偉峰, 高津哲也, 小谷健二, 鈴木亮, 野呂恭成, 竹谷裕平  日本水産学会大会講演要旨集(CD-ROM)  2021-  2021
• 陸奥湾のマダラ着底稚魚期までの累積生残率の推定

  高津哲也, 野呂恭成, 菊谷尚久, 吉田達, 伊藤欣吾, 三浦太智, 松谷紀明, 董安然, 中屋光裕  日本水産学会大会講演要旨集(CD-ROM)  2021-  2021
• 津軽海峡周辺におけるキアンコウの初期生態

  高 偉峰, 中屋光裕, 髙津哲也, 竹谷裕平, 鈴木 亮, 野呂恭成  水産海洋研究  84-  (3)  228  -229  2020/08  [Not refereed][Not invited]
  
• 秋田県男鹿半島の漁港内メソコズムにおけるハタハタの成長とその年変動

  甲本亮太, 髙津哲也, 佐藤正人  水産海洋研究  84-  (3)  225  -226  2020/08  [Not refereed][Not invited]
  
• ホッケ生活史初期の成長

  河村眞美, 中屋光裕, 髙津哲也, 巣山 哲, 鈴木祐太郎, 高畠信一  水産海洋研究  84-  (3)  223  -224  2020/08  [Not refereed][Not invited]
  
• 陸奥湾における1989～2019年マダラ着底稚魚分布密度調査による加入量予測

  髙津哲也, 中屋光裕, 神山晃汰, 亀井佳彦, 小林直人, 飯田高大, 野呂恭成  水産海洋研究  84-  (3)  221  -221  2020/08  [Not refereed][Not invited]
  
• スケトウダラ仔魚の孵化輪紋を用いた母親効果仮説の検証

  梶原慧太郎, 鈴木孝太, 鹿野陽太, 中屋光裕, 高津哲也  日本水産学会大会講演要旨集  2017-  2017
• スケトウダラの卵サイズ選択的生残

  梶原慧太郎, 鈴木孝太, 鹿野陽太, 中屋光裕, 高津哲也  日本水産学会北海道支部大会講演要旨集  2016-  2016
• 道南津軽暖流域で採集されたヒレグロ浮遊仔魚

  鈴木孝太, 中村広和, 中屋光裕, 折野和樹, 梶原慧太郎, 佐藤義崇, 高津哲也  水産海洋学会研究発表大会講演要旨集  2015-  2015
• 噴火湾におけるアカガレイ卵径の季節・年変動

  田村純一, 鈴木孝太, 中屋光裕, 梶原慧太郎, 佐藤義崇, 折野和樹, 高津哲也  水産海洋学会研究発表大会講演要旨集  2015-  2015
• スケトウダラの卵径と仔魚の耳石成長率との関係

  梶原慧太郎, 鈴木孝太, 田村淳一, 鹿野陽太, 高津哲也  水産海洋学会研究発表大会講演要旨集  2015-  2015
• 練習船を活用した復興支援教育・研究活動の提案

  高津 哲也  水産海洋研究  76-  (3)  166  -167  2012/08/01
• ヤナギムシガレイの資源生態調査と管理手法開発

  高梨勝美, 吉田雅範, 三浦太智, 高津哲也, 松田沙織  青森県産業技術センター水産総合研究所事業報告  2010-  1  -11  2012/02  [Not refereed][Not invited]
  
• ヤナギムシガレイの資源生態調査と管理手法開発事業

  高梨勝美, 吉田雅範, 高津哲也, 松田沙織  青森県産業技術センター水産総合研究所事業報告  2009-  1  -10  2011/10  [Not refereed][Not invited]
  
• Larval feeding intensity and year class strength of pointhead flounder Cleisthenes pinetorum in Funka Bay

  HIRAOKA Yuko, TAKATSU Tetsuya, OHNO Yusuke, OKUMURA Hiroya, TAKAHASHI Hideaki, TAKAHASHI Toyomi  Bulletin of the Japanese Society of Fisheries Oceanography  73-  (2)  90  -101  2009/05/28  [Refereed][Not invited]
   

  ソウハチは、サハリン、千島列島、北海道沿岸と、本州太平洋側では福島県まで、日本海側では沿海地方から東シナ海北部まで分布する異体類の1種であり、北海道周辺では刺網や沖合底曳網漁業の主要対象種のひとつである。襟裳岬から噴火湾および恵山岬にいたる道南太平洋海域の年間漁獲量の変動は、1954年から2004年の間で、最大25倍の差があり、その資源量も大きく変動しているものと考えられる。このような漁獲量や資源量の変動原因を明らかにするためには、加入量変動を左右する生活史初期の生残・減耗過程を解明する必要がある。本研究は、2003年から2006年に噴火湾内で採集された摂餌開始期のソウハチ仔魚の消化管内容物を調べ、2001-2003年の仔魚密度と2001年8月に採集された仔魚の消化管内容物調査の結果と比較することで、1）摂餌に強く影響を与える環境要因、2）年級群強度を左右する要因、を解明することを目的とした。
• アカガレイの成長遅滞

  岩川 浩大, 高津 哲也, 高橋 豊美  水産海洋研究  72-  (1)  42  -43  2008/02/28
• The 38th symposium on the sub-arctic fisheries and oceanography

  高津 哲也  水産海洋研究  72-  (1)  37  -37  2008/02/28
• 第38回北洋研究シンポジウム : 「近年の噴火湾における海洋環境と漁業資源の変動」-速報-

  高津 哲也, 渡野邉 雅道  水産海洋研究  71-  (2)  155  -155  2007/05/28
• 陸奥湾における底生魚類の初期生息環境の年変動

  高津 哲也, 伊村 一雄, 長谷川 藍, 福井 康喜, 城 孝至  水産海洋研究  69-  (1)  55  -56  2005/02/28
• 陸奥湾におけるヤナギムシガレイの年齢組成とレジｰムシフトの関係

  高津 哲也, 伊村 一雄  水産海洋研究  68-  (4)  270  -270  2004/11/10
• 函館湾におけるマコガレイ仔魚の日周鉛直分布

  関口督人, 中屋光裕, 城幹昌, 高津哲也  日本水産学会大会講演要旨集  2004-  41  2004/03/31  [Not refereed][Not invited]
  
• マコガレイ仔稚魚の成長履歴解析

  城幹昌, 高津哲也, 中屋光裕, 高橋豊美  日本水産学会大会講演要旨集  2004-  56  2004/03/31  [Not refereed][Not invited]
  
• Field research on spatial and temporal distributions of demersal fish larvae and juveniles and their prey abundance

  T Takatsu  NIPPON SUISAN GAKKAISHI  69-  (4)  543  -546  2003/07  [Not refereed][Not invited]
  
• Age and Growth of Marbled Sole (Preuronectes yokohamae) in the Coastal Waters of Western Aomori Prefecture, Japan

  KOOKA Kouji, TAKATSU Tetsuya, NAGA Takahiro, HAYAKAWA Yutaka, KAMIHARAKO Tsuguo, TAKAHASHI Toyomi  Bulletin of the Faculty of Fisheries, Hokkaido University  51-  (2)  121  -126  2000/09
• Survival of the Pacific cod juveniles in Mutsu Bay, Japan

  TAKASU Tetsuya  Bulletin of the Japanese Society of Fisheries Oceanography  62-  (2)  151  -155  1998/05/01

Books etc

• 道南おさかな図鑑

  魚に魅せられた北大の研究者たち, 井尻成保, 今村 央, 浦 和寛, 河合俊郎, 工藤秀明, 清水宗敬, ジョン・バウアー, 髙津哲也, 東藤孝, 富安 信, 中屋光裕, 平松尚志, 藤本貴史, 宗原弘幸, 山村織生, 山本 潤 (マダラ，スケトウダラ，ソウハチ，マコガレイ，クロマグロ，トヤマエビ，アカガレイ，カタクチイワシ)
  海文堂出版 2023/10 (ISBN: 9784303800116) 97p
• 卓越年級群 : カレイとタラの生残戦略

  髙津, 哲也 (Single work)
  海文堂出版 2022/03 (ISBN: 9784303800079) 127p
• 水産科学・海洋環境科学実習（北海道大学水産学部練習船教科書編纂委員会編）

  中屋光裕, 髙津哲也 (Joint work魚類・ベントス測定)
  海文堂出版 2019/07
• Anniversary Book of Hokusui Public Foundation

  TAKATSU Tetsuya (ContributorEducational contribution of Hokusui Foundation)
  Hokusui Public Foundation 2011
• カイアシ類学入門－水中の小さな巨人たちの世界（長澤和也編）

  東海大学出版会 2005

Presentations

• 陸奥湾におけるマダラ資源増加期の稚魚の胃内容物組成  [Not invited]

  董 安然, 髙津哲也, 石川智也, 中屋光裕

  令和6年度日本水産学会春季大会  2024/03
• マダラ雌親の体重と卵径・ふ化仔魚の体長と耳石径の関係  [Not invited]

  渡邊一生, 髙津哲也, 松本涼太郎, 中屋光裕

  2023年度水産海洋学会研究発表大会  2023/11
• 陸奥湾におけるマダラ稚魚の食性と加入量の関係  [Not invited]

  董 安然, 髙津哲也, 渡邊一生, 中屋光裕

  令和5年度日本水産学会春季大会  2023/03
• 陸奥湾におけるマダラ仔稚魚2022年級群の成長履歴  [Not invited]

  渡邊一生, 髙津哲也, 中屋光裕

  稚魚研究会  2022/11
• 陸奥湾における2016年以降のマダラ着底稚魚の食性  [Not invited]

  董 安然, 髙津哲也, 中屋光裕

  稚魚研究会  2022/11
• 陸奥湾産マダラ稚魚2022年級群が小型であった理由  [Not invited]

  髙津哲也, 渡邊一生, 松谷紀明, 野呂恭成, 中屋光裕

  令和4年度日本水産学会秋季大会  2022/09
• 陸奥湾のマダラ着底稚魚期までの累積生残率の推定  [Not invited]

  髙津哲也, 野呂恭成, 菊谷尚久, 吉田 達, 伊藤欣吾, 三浦太智, 松谷紀明, 董 安然, 中屋光裕

  令和3年度日本水産学会秋季大会  2021/09
• キアンコウ仔魚の卵帯からのふ出に関する研究  [Invited]

  石川智也, 中屋光裕, 高偉峰, 髙津哲也, 小谷健二, 鈴木亮, 野呂恭成, 竹谷裕平

  令和3年度日本水産学会秋季大会  2021/09
• 道北におけるホッケ若魚の食性と栄養状態  [Not invited]

  髙橋昂大, 中屋光裕, 大門純平, 髙津哲也, 鈴木祐太郎

  令和3年度日本水産学会秋季大会  2021/09
• 噴火湾におけるアカガレイ2016, 2017 年級群の食性と栄養状態の差  [Not invited]

  水野悠, 髙津哲也, 中屋光裕

  令和3年度日本水産学会秋季大会  2021/09
• 噴火湾の底生魚類が捕食するスケトウダラ稚魚の特徴  [Not invited]

  髙津哲也, 納谷晃弘, 柳澤和彦, 中屋光裕

  水産海洋学会 地域研究集会 第50 回北洋研究シンポジウム  2021/03
• 噴火湾のソウハチ資源が近年増大している理由  [Invited]

  髙津哲也

  令和２年度日本水産学会北海道支部大会  2020/12
• 陸奥湾におけるマダラ稚魚の生残率の経年変化

  髙津哲也, 中屋光裕, 神山晃汰

  2019年度稚魚研究会  2019/11
• スケトウダラ仔魚の扁平石孵化チェック径を用いた母親効果の検証  [Not invited]

  梶原慧太郎, 中屋光裕, 鈴木孝太, 鹿野陽太, 髙津哲也

  2018年度稚魚研究会  2018/12
• 亜寒帯域における多獲性底生魚類の生活史の解明と資源変動機構に関する研究  [Invited]

  髙津哲也

  2018年度水産海洋学会研究発表大会  2018/11
• スケトウダラ太平洋系群稚魚の着底前後における食性と栄養状態  [Not invited]

  中脇鴻陽, 鈴木孝太, 納谷晃弘, 中屋光裕, 髙津哲也

  平成30年度日本水産学会春季大会  2018/03
• スケトウダラ太平洋系群の卵密度が1月後半に高い理由  [Not invited]

  髙津哲也, 鈴木孝太, 中谷敏邦, 中脇鴻陽, 山岡秀圭, 納谷晃弘, 中屋光裕

  平成30年度日本水産学会春季大会  2018/03
• 北海道噴火湾における沿岸親潮流入期のかいあし類及び尾虫類の種組成と密度の経時・経年変化  [Not invited]

  山岡秀圭, 鈴木孝太, 中屋光裕, 髙津哲也

  平成30年度日本水産学会春季大会  2018/03
• スケトウダラ仔魚の孵化輪紋を用いた母親効果仮説の検証  [Not invited]

  梶原慧太郎, 鈴木孝太, 鹿野陽太, 中屋光裕, 高津哲也

  日本水産学会大会講演要旨集  2017/03
• 噴火湾におけるキタクシノハクモヒトデの成長様式とその特徴  [Not invited]

  折野和樹, 石金晃介, 鈴木孝太, 中屋光祐, 高津哲也

  日本水産学会大会講演要旨集  2017/03
• オウゴンムラソイSebastes nudusの初期形態発達様式  [Not invited]

  石金晃介, 中屋光裕, 鈴木孝太, 高津哲也

  日本水産学会北海道支部大会講演要旨集  2016/10
• スケトウダラの卵サイズ選択的生残  [Not invited]

  梶原慧太郎, 鈴木孝太, 鹿野陽太, 中屋光裕, 高津哲也

  日本水産学会北海道支部大会講演要旨集  2016/10
• 噴火湾におけるキタクシノハクモヒトデの腕骨輪紋の年齢形質としての有効性  [Not invited]

  折野和樹, 石金晃介, 鈴木孝太, 中屋光裕, 高津哲也

  日本水産学会北海道支部大会講演要旨集  2016/10
• 青森県周辺海域におけるキアンコウの食性と栄養状態  [Not invited]

  竹谷裕平, 竹谷裕平, 高津哲也, 中屋光裕

  日本水産学会北海道支部大会講演要旨集  2016/10
• 函館周辺海域におけるイシガレイ稚魚の成長履歴と成育場環境  [Not invited]

  佐藤義崇, 中屋光裕, 浦杉朝子, 藤田智哉, 高津哲也

  日本水産学会北海道支部大会講演要旨集  2016/10
• 噴火湾と陸奥湾におけるスケトウダラ着底稚魚平均密度の年変動  [Not invited]

  高津哲也, 鈴木孝太, 稲垣祐太, 亀井佳彦, 小林直人, 中屋光裕

  日本水産学会大会講演要旨集  2016/09
• 津軽海峡の沿岸漁業の現状  [Not invited]

  高津哲也, 中屋光裕

  水産海洋研究  2016/08
• 青森県周辺海域におけるキアンコウの成長と成熟  [Not invited]

  竹谷裕平, 高津哲也, 山中智之, 柴田泰宙, 中屋光裕

  日本水産学会大会講演要旨集  2016/03
• 北海道噴火湾におけるアカガレイ卵径の経時変動  [Not invited]

  田村純一, 高津哲也, 鈴木孝太, 中屋光裕

  日本水産学会大会講演要旨集  2016/03
• 津軽海峡周辺海域におけるホッケの初期成育環境と成長の関係  [Not invited]

  猪俣安奈, 高津哲也, 中屋光裕

  日本水産学会大会講演要旨集  2016/03
• 噴火湾と陸奥湾におけるカレイ類とマダラの漁獲量の変化とその要因  [Not invited]

  高津哲也, 中屋光裕, 鈴木孝太, 稲垣祐太

  水産海洋研究  2015/11
• 陸奥湾におけるマダラ2011‐2013年級群の初期成長・豊度・生残の特徴  [Not invited]

  林晃弘, 高津哲也, 中屋光裕, 亀井佳彦, 小林直人, 野呂恭成

  日本水産学会大会講演要旨集  2015/03
• 仙台湾におけるマガレイ雌の摂餌日周性と日間摂餌率  [Not invited]

  小林由紀, 高津哲也, 栗田豊

  日本水産学会大会講演要旨集  2015/03
• 北海道沖日本海におけるホッケ仔稚魚の食性  [Not invited]

  石森謙太郎, 浅見大樹, 鈴木祐太郎, 城幹昌, 藤岡崇, 中尾光裕, 高津哲也

  日本水産学会大会講演要旨集  2015/03
• 道北日本海~オホーツク海に分布するマガレイの稚魚成育場が異なる2つの海域に存在する意義  [Not invited]

  城幹昌, 石田良太郎, 佐藤敦一, 小林由紀, 高津哲也, 山口宏史

  水産海洋学会研究発表大会講演要旨集  2015
• 函館湾周辺海域沿岸に生息するイシガレイ稚魚の成長と成育場環境  [Not invited]

  佐藤義崇, 中屋光裕, 浦杉朝子, 高津哲也

  水産海洋学会研究発表大会講演要旨集  2015
• スケトウダラの卵径と仔魚の耳石成長率との関係  [Not invited]

  梶原慧太郎, 鈴木孝太, 田村淳一, 鹿野陽太, 高津哲也

  水産海洋学会研究発表大会講演要旨集  2015
• 道南津軽暖流域で採集されたヒレグロ浮遊仔魚  [Not invited]

  鈴木孝太, 中村広和, 中屋光裕, 折野和樹, 梶原慧太郎, 佐藤義崇, 高津哲也

  水産海洋学会研究発表大会講演要旨集  2015
• アカガレイ仔稚魚の成長と耳石輪紋形成の関係  [Not invited]

  中屋光裕, 鈴木孝太, 高津哲也, 城幹昌, 松田泰平

  水産海洋学会研究発表大会講演要旨集  2015
• 噴火湾におけるアカガレイ卵径の季節・年変動  [Not invited]

  田村純一, 鈴木孝太, 中屋光裕, 梶原慧太郎, 佐藤義崇, 折野和樹, 高津哲也

  水産海洋学会研究発表大会講演要旨集  2015
• 噴火湾におけるアカガレイ卵仔稚の輸送過程の把握―卵仔稚の比重―  [Not invited]

  鈴木孝太, 中屋光裕, 松田泰平, 柳海均, 高津哲也

  日本水産学会大会講演要旨集  2014/09
• 噴火湾におけるアカガレイ資源量の経年変化  [Not invited]

  高津哲也, 稲垣祐太, 前田辰昭, 鈴木孝太, 小林由紀, 中屋光裕

  日本水産学会大会講演要旨集  2014/03
• 北海道沖日本海におけるホッケ仔稚魚の食性  [Not invited]

  石森謙太郎, 浅見大樹, 鈴木祐太郎, 城幹昌, 藤岡崇, 中屋光裕, 高津哲也

  日本水産学会大会講演要旨集  2014/03
• 噴火湾における底生魚類豊度の経年変化  [Not invited]

  稲垣祐太, 亀井佳彦, 小林直人, 高橋豊美, 高津哲也

  日本水産学会大会講演要旨集  2014/03
• RNA/DNA比および耳石外縁成長量を指標としたマガレイ稚魚の成長  [Not invited]

  城幹昌, 石田良太郎, 佐藤敦一, 小林由紀, 高津哲也, 山口宏史

  日本水産学会大会講演要旨集  2013/09
• 貧酸素環境におけるアカガレイHippoglossoides dubiusの成長・栄養状態の向上  [Not invited]

  稲垣祐太, 高津哲也, 木村賢史, 鹿野陽太, 高橋豊美, 亀井佳彦, 小林直人, 前田辰昭

  日本海洋学会大会講演要旨集  2013/08
• 陸奥湾の海洋環境の変化がマコガレイの豊度・成長に及ぼす影響  [Not invited]

  瀬田智文, 高津哲也, 井上翔一, 篠田晃司

  日本水産学会大会講演要旨集  2013/03
• 成育場間でのマガレイ稚魚(北部日本海~オホーツク海系群)の食性の比較  [Not invited]

  小林由紀, 高津哲也, 城幹昌, 山口宏史

  日本水産学会大会講演要旨集  2013/03
• ヒレグロの摂餌強度と栄養状態に及ぼす貧酸素水の影響  [Not invited]

  稲垣祐太, 上野山隆生, 米田典子, 高橋豊美, 高津哲也

  日本水産学会大会講演要旨集  2013/03
• オホーツク海と日本海北部沿岸域に生息するマガレイ稚魚の食性の比較  [Not invited]

  小林由紀, 高津哲也, 城幹昌, 山口宏史

  水産海洋学会研究発表大会講演要旨集  2013
• 陸奥湾におけるマクロベントス密度と群集型の経年変化  [Not invited]

  篠田晃司, 高津哲也, 梶谷俊介, 井上翔一, 瀬田智文, 稲垣祐太

  水産海洋学会研究発表大会講演要旨集  2012/11
• 練習船を活用した復興支援教育・研究活動の提案  [Not invited]

  高津哲也

  水産海洋研究  2012/08
• アカガレイ摂餌開始期仔魚の耳石輪紋幅の年変動  [Not invited]

  福井翔太郎, 高津哲也, 大野雄介, 前田晃子, 鹿野陽太, 中谷敏邦, 前田辰昭

  日本水産学会大会講演要旨集  2012/03
• 陸奥湾におけるヤナギムシガレイ豊度に影響を与える環境要因  [Not invited]

  井上翔一, 高津哲也, 瀬田智文, 篠田晃司

  日本水産学会北海道支部大会講演要旨集  2012
• 2011年秋季に陸奥湾で発生した貧酸素水による底生魚類の減少  [Not invited]

  高津哲也, 井上翔一, 篠田晃司, 瀬田智文, 稲垣祐太

  日本水産学会北海道支部大会講演要旨集  2012
• 噴火湾における異体類仔魚の餌生物としての尾虫類Oikopleura spp.の役割  [Not invited]

  橋本雄太郎, 中谷敏邦, 前田晃子, 大野雄介, 鹿野陽太, 高津哲也

  日本水産学会大会講演要旨集  2011/03
• 日本海青森県沿岸におけるヤナギムシガレイの年齢と成長  [Not invited]

  松田沙織, 高津哲也, 高梨勝美

  日本水産学会大会講演要旨集  2011/03
• 噴火湾におけるマクロベントス密度の経年変化  [Not invited]

  稲垣祐太, 高橋豊美, 蘆田雄毅, 高津哲也

  日本水産学会大会講演要旨集  2011/03
• 練習船を活用した復興支援教育・研究活動の提案  [Not invited]

  高津哲也

  水産海洋学会研究発表大会講演要旨集  2011
• 北海道噴火湾におけるスケトウダラ仔魚成長様式の年変動  [Not invited]

  鹿野陽太, 中谷敏邦, 橋本雄太郎, 福井翔太郎, 高津哲也

  水産海洋学会研究発表大会講演要旨集  2011
• 噴火湾のマクロベントス密度に及ぼす環境要因  [Not invited]

  稲垣祐太, 高橋豊美, 蘆田雄毅, 高津哲也

  水産海洋学会研究発表大会講演要旨集  2011
• 噴火湾におけるアカガレイ仔魚の成長様式  [Not invited]

  大野雄介, 高津哲也, 前田晃子, 高橋豊美, 平岡優子, 松田泰平

  日本水産学会大会講演要旨集  2010/03
• DNAマーカーを用いたカレイ科2種の分子集団遺伝学的解析  [Not invited]

  尾崎匠磨, 武田圭史, 高津哲也, 阿部周一

  日本水産学会大会講演要旨集  2010/03
• 茨城県沖における異体類仔魚の時空間分布とマコガレイおよびムシガレイ仔魚の摂餌生態  [Not invited]

  細見一樹, 渡邊直樹, 高橋正和, 高津哲也

  日本水産学会大会講演要旨集  2009/03
• ミトコンドリアDNAを用いたカレイ科2種の分子系統学的ならびに分子集団遺伝学的解析  [Not invited]

  武田圭史, 高津哲也, 東典子, 阿部周一, 高橋豊美

  日本水産学会大会講演要旨集  2009/03
• 北海道噴火湾におけるアカガレイ仔魚の食性  [Not invited]

  前田晃子, 中谷敏邦, 大野雄介, 高津哲也

  日本水産学会大会講演要旨集  2009/03
• 噴火湾におけるマガレイ仔魚の摂餌生態  [Not invited]

  佐藤幸太朗, 平岡優子, 高津哲也

  日本水産学会北海道支部大会講演要旨集  2009
• アイナメ属3種およびその雑種の耳石を用いた成長速度の比較  [Not invited]

  木村幹子, 高津哲也, 河田雅圭, 宗原弘幸

  日本生態学会大会講演要旨集  2008/03
• The 38th symposium on the sub-arctic fisheries and oceanography  [Not invited]

  高津 哲也

  水産海洋研究  2008/02
• アカガレイの成長遅滞  [Not invited]

  岩川浩大, 高津哲也, 高橋豊美

  水産海洋研究  2008/02
• 噴火湾におけるアカガレイの初期成長様式  [Not invited]

  大野雄介, 中谷敏邦, 高津哲也

  日本水産学会大会講演要旨集  2007/09
• 冬季から春季に茨城沖に出現する異体類仔魚の分布様式  [Not invited]

  細見一樹, 渡邊直樹, 高橋正和, 高津哲也

  日本水産学会大会講演要旨集  2007/09
• 陸奥湾におけるマガレイPseudopleuronectes herzensteiniの年級群別成長の違い  [Not invited]

  坂井圭昌, 高津哲也, 高橋豊美

  日本水産学会大会講演要旨集  2007/09
• 陸奥湾におけるイカナゴ仔稚魚の成長様式  [Not invited]

  杉山甲斐, 高津哲也, 福井康喜

  日本水産学会大会講演要旨集  2007/09
• ミトコンドリアDNAを用いたカレイ科2種の分子系統学的解析  [Not invited]

  武田圭史, 高津哲也, 阿部周一

  日本水産学会大会講演要旨集  2007/09
• 第38回北洋研究シンポジウム : 「近年の噴火湾における海洋環境と漁業資源の変動」-速報-  [Not invited]

  高津 哲也, 渡野邉 雅道

  水産海洋研究  2007/05
• 親潮流域に面する湾内の貝類相:根室湾・厚岸湾・噴火湾・函館(木古内)湾・陸奥湾・大槌湾  [Not invited]

  山崎友資, 高田良二, 高津哲也, 五嶋聖治

  日本ベントス学会・日本プランクトン学会合同大会講演要旨集  2006/09
• 陸奥湾における底生魚類の初期生息環境の年変動  [Not invited]

  高津 哲也, 伊村 一雄, 長谷川 藍, 福井 康喜, 城 孝至

  水産海洋研究  2005/02
• 陸奥湾におけるヤナギムシガレイの年齢組成とレジｰムシフトの関係  [Not invited]

  高津 哲也, 伊村 一雄

  水産海洋研究  2004/11
• マコガレイ仔稚魚の成長履歴解析  [Not invited]

  城幹昌, 高津哲也, 中屋光裕, 高橋豊美

  日本水産学会大会講演要旨集  2004/03
• 函館湾におけるマコガレイ仔魚の日周鉛直分布  [Not invited]

  関口督人, 中屋光裕, 城幹昌, 高津哲也

  日本水産学会大会講演要旨集  2004/03
• 網口ビデオ録画可能な試作小型ソリネットの曳網状態  [Not invited]

  清水晋, 高津哲也, 木村修

  日本水産学会北海道支部大会講演要旨集  2004
• 2002年函館湾におけるマコガレイ仔稚魚のふ化日組成  [Not invited]

  城幹昌, 高津哲也, 中屋光裕, 関口督人

  日本水産学会北海道支部大会講演要旨集  2003/11
• 底生魚類仔稚魚の時空間分布と餌料環境に関する研究  [Not invited]

  高津哲也

  日本水産学会大会講演要旨集  2003/04
• 噴火湾におけるソウハチ仔魚の食性  [Not invited]

  平岡優子, 栗藤亜希子, 伊村一雄, 高津哲也

  日本水産学会大会講演要旨集  2003/04
• 陸奥湾におけるマガレイ2001年卓越年級群の初期餌料環境  [Not invited]

  高津哲也, 伊村一雄, 南条暢聡, 高橋豊美

  日本水産学会北海道支部大会講演要旨集  2002/11
• マコガレイ仔魚へん平石上にみられる微細輪紋の日周性確認  [Not invited]

  城幹昌, 高津哲也, 中屋光裕, 東谷知美, 高橋豊美

  日本水産学会大会講演要旨集  2002/03
• 陸奥湾におけるマダラ稚魚の成長履歴と餌生物環境  [Not invited]

  西隆介, 高津哲也, 吉田裕幸

  日本水産学会大会講演要旨集  2002/03
• 陸奥湾におけるイカナゴ仔魚の摂餌強度と相対成長  [Not invited]

  南条暢聡, 伊村一雄, 高津哲也

  日本水産学会大会講演要旨集  2002/03
• 函館湾におけるマコガレイ仔魚の摂餌強度と栄養状態の年変動  [Not invited]

  中神正康, 高津哲也, 井上善美, 栗藤亜希子, 城幹昌

  日本水産学会大会講演要旨集  2002/03
• 北部日本海に生息するスケトウダラの年齢組成  [Not invited]

  小岡孝治, 高津哲也, 中谷敏邦, 高橋豊美

  日本水産学会大会講演要旨集  1999/09
• 北部日本海に生息するスケトウダラの摂餌強度  [Not invited]

  小岡孝治, 高津哲也, 中谷敏邦, 高橋豊美

  日本水産学会大会講演要旨集  1999/09
• 函館湾におけるマコガレイ仔稚魚の捕食者としてのエビジャコの時空間分布  [Not invited]

  中屋光裕, 高津哲也, 中神正康, 高橋豊美

  日本水産学会大会講演要旨集  1999/04
• 陸奥湾湾口部および津軽海峡におけるマダラ着底稚魚の食物組成と相対成長  [Not invited]

  高津哲也, 小田切譲二

  日本水産学会大会講演要旨集  1999/04
• 道南津軽海峡沿岸におけるマコガレイ稚魚の食性  [Not invited]

  中神正康, 松田泰平, 中尾博己, 今野幸広, 山本禎, 高津哲也

  日本水産学会大会講演要旨集  1998/09
• 北海道南西沖の中層に生息するスケトウダラの成長  [Not invited]

  小岡孝治, 高津哲也, 石田良太郎, 中谷敏邦, 亀井佳彦, 高木省吾, 高橋豊美

  日本水産学会大会講演要旨集  1998/09
• 陸奥湾におけるマダラ着底稚魚の食物組成と相対成長  [Not invited]

  高津哲也, 吉田裕幸

  日本水産学会大会講演要旨集  1998/09
• 北海道八雲沿岸域におけるキュウリウオ科仔魚の分布と初期餌料  [Not invited]

  井口謙, 中谷敏邦, 高津哲也, 高橋豊美

  日本水産学会大会講演要旨集  1998/09
• イシガレイ浮遊期仔魚によるオタマボヤ包巣原基の捕食  [Not invited]

  鈴木祐輔, 高津哲也, 志賀直信

  日本水産学会大会講演要旨集  1998/09
• Survival of the Pacific cod juveniles in Mutsu Bay, Japan  [Not invited]

  TAKASU Tetsuya

  Bulletin of the Japanese Society of Fisheries Oceanography  1998/05
• Distribution of dab fry in Hakodate Bay and Kikonai bay.  [Not invited]

  中神正康, 高津哲也, 高橋豊美

  日本水産学会大会講演要旨集  1998/04
• Factors in generating year group of excellent yield of dab in Mutsu Bay.  [Not invited]

  高津哲也, 高橋豊美

  日本水産学会大会講演要旨集  1998/04
• Downward flow process of rainbow smelt fingerling in Yamasaki River of Hokkaido.  [Not invited]

  井口謙, 高津哲也, 中谷敏邦, 高橋豊美

  日本水産学会大会講演要旨集  1997/04
• Initial survival process of Alaska pollack in Funka Bay.  [Not invited]

  杉本晃一, 中谷敏邦, 高津哲也, 高橋豊美

  日本水産学会大会講演要旨集  1997/04
• Hatching day composition of Alaska pollack grounding larva distributed in Funka Bay in summer.  [Not invited]

  杉本晃一, 中谷敏邦, 高津哲也, 高橋豊美

  日本水産学会大会講演要旨集  1997/04
• Food habit of Japan sea wrymouth larva in Mutsu Bay.  [Not invited]

  高津哲也, 中谷敏邦, 高橋豊美

  日本水産学会大会講演要旨集  1997/04
• Bait selection of Alaska pollack inhabiting in the middle layer of the northern Sea of Japan.  [Not invited]

  小岡孝治, 高津哲也, 中谷敏郎, 高橋豊美

  日本水産学会大会講演要旨集  1997/04
• Appearance mode of the floating fingerling in Mutsu Bay in the spring.  [Not invited]

  高津哲也, 中谷敏邦, 高橋豊美

  日本水産学会北海道支部大会講演要旨集  1996/12
• Vertical distribution of Alaska pollack and Euphausiacea inhabiting northern area of the Sea of Japan.  [Not invited]

  小岡孝治, 高津哲也, 中谷敏邦, 高橋豊美

  日本水産学会大会講演要旨集  1996/10
• Food habit of Alaska pollack distributed off Tokachi in spring.  [Not invited]

  松本明男, 中谷敏邦, 高津哲也, 高橋豊美

  日本水産学会北海道支部大会講演要旨集  1995/12
• Distribution and food habit of demersal fishes in Kikonai Bay.  [Not invited]

  佐々木美枝子, 佐野満広, 石野健吾, 高津哲也, 高橋豊美

  日本水産学会北海道支部大会講演要旨集  1995/12
• Vertical distribution of main bait organism of Alaska pollack in the Sea of Japan.  [Not invited]

  小岡孝治, 高津哲也, 中谷敏邦, 高橋豊美

  日本水産学会北海道支部大会講演要旨集  1995/12
• Maturation of female rainbow smelt in Funka Bay, Hokkaido.  [Not invited]

  井口謙, 中谷敏邦, 高津哲也, 高橋豊美

  日本水産学会北海道支部大会講演要旨集  1995/12
• Annual fluctuation of distribution density of Pacific cod larva in Mutsu Bay.  [Not invited]

  高津哲也, 中谷敏邦, 高橋豊美

  日本水産学会北海道支部大会講演要旨集  1995/12
• Life year cycle and distribution of snake prickleback in Funka Bay, Hokkaido.  [Not invited]

  筒井浩之, 中谷敏邦, 高津哲也, 高橋豊美

  日本水産学会北海道支部大会講演要旨集  1995/12
• 噴火湾における摂餌開始期のスケトウダラ仔魚の餌生物環境とその月変化  [Not invited]

  中谷敏邦, 高津哲也, 高橋豊美

  日本水産学会大会講演要旨集  1995/04

Association Memberships

• 日本水産学会   日本魚類学会   日本水産増殖学会   日本プランクトン学会   水産海洋学会   The Ichthyological Society of Japan   The Japanese Society for Aquaculture Research   The Plankton Society of Japan   

Research Projects

• Effects of marine heatwaves on the early survival processes of walleye pollock and Pacific cod: a test of the growth and prey quality-quantity hypothesis

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

  Date (from‐to) : 2024/04 -2028/03 

  Author : Tetsuya TAKATSU
• 噴火湾における底生生物資源と漁場環境に関する研究

  公益財団法人北水協会：公益財団法人北水協会研究助成事業

  Date (from‐to) : 2011/04 -2025/03 

  Author : 坂岡桂一郎, 亀井佳彦, 大木 淳之, 阿部泰人, 大西広二, 久万健志, 木村修
• Detection of maternal effects using field-collected Pacific cod larvae and juveniles and its application to resource management

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

  Date (from‐to) : 2021/04 -2024/03 

  Author : TAKATSU Tetsuya, NAKAYA mitsuhiro

   

  本研究の目的は，産業重要種であるマダラGadus macrocephalusの野外採集仔魚から「母親効果」を検出し，母親効果を考慮した漁獲への変更が，資源量回復にどの程度貢献するのか解明することである。また，環境変動が資源量変動におよぼす影響も同時解析することで，母親効果を利用した資源保護策の有効性も明らかにする． まず，これまでのマダラの親魚量と着底期までの仔稚魚の生残率の関係を明らかにするために，主要産卵場の一つである青森県陸奥湾の1989年から2019年までの両者の豊度の間で累積的生残率を推定し，その年変動を明らかにした．その結果，累積的生残率は仔魚期の前半にあたる2月下旬から3月中旬の水温が高いほど高く，仔魚期の後半と稚魚期にあたる3月下旬から5月下旬の水温が7.6℃で最大値を示すことを明らかにした。水温はそれぞれ全変動の23%と22%を説明した。 次に，孵化仔魚の耳石輪紋に形成される孵化チェック（通常より太い日周輪）の大きさが，卵径に比例するか明らかにするために，2022年1月に津軽海峡で採集した成熟魚を用いて人工授精・飼育を行い，孵化直前の卵と孵化直後の仔魚を得た。また成熟魚の体長や年齢，栄養状態が卵径におよぼす影響を明らかにするために，耳石による年齢査定と魚体測定を行った。 野外採集仔魚は2021年4月と2022年2月に，主要産卵場である青森県陸奥湾でプランクトンネットによる採集を行った。同時に物理環境データと，仔魚の餌生物であるかいあし類ノープリウスの採集を行った。
• Effects of egg size, larval growth rate, and juvenile nutritional condition on population dynamics of walleye pollock

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

  Date (from‐to) : 2016/04 -2019/03 

  Author : TAKATSU Tetsuya, NAKAYA Mitsuhiro

   

  To clarify survival processes in Japan Pacific Stock (JPS) of walleye pollock Gadus chalcogrammus, maternal effect and somatic condition were investigated in Funka Bay in 2016-2018. No annual difference in hatch-check diameter on larval otolith derived from maternal was observed between three year-classes. Notochord lengths in late February and early March were small in low water temperature years. The 75-77% of settled juveniles collected in mid-June have settlement checks around their otoliths and settled fork-lengths were estimated at 67.2-69.0 mm from the relationship between fork length and otolith diameter. Feeding intensities and somatic conditions of juveniles decreased in Tsugaru Warm Current water from August to October, then those recovered with water temperature decreasing after October. Annual fluctuations of somatic condition and growth rate might influence the recruitment of JPS.
• Occurrence mechanism of strong-year classes in flathead flounder Hippoglossoides dubius by the assessment of transport process and prey abundance for larvae and juveniles

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

  Date (from‐to) : 2013 -2015 

  Author : Takatsu Tetsuya, HOSHI NAOKI, NAKAYA MITSUHIRO, ISODA YUTAKA, INAGAKI YUTA, KANO YOTA, NAKATANI TOSHIKUNI, SUZUKI KOTA, TAMURA JUN'ICHI

   

  To clarify the occurrence mechanism of strong-year classes in flathead flounder Hippoglossoides dubius, transport process of pelagic larvae and juveniles and settled area of juveniles were investigated in Funka Bay and its vicinity in 2013-2015 FY. In May 2013, late pelagic stage larvae were collected with MOHT- and FMT-nets around the area off Muroran City located at the north-east end of the bay, but no larva was collected in 2014-2015. It might be important for the recruitment success in the 2013 year-class that the clockwise vortex off Muroran captured the larvae was retained by the predominantly northwesterly winds. In this vortex, suitable water temperature (4.1-5.6 degrees Celsius) and prey abundance were observed for larval growth. In contrast in August-December through 2013-2015, no settled juvenile was collected on the sea floor with an otter trawl net in and out of the bay with <98-m and 95-354-m bottom depths, respectively.
• Verification of the turbulence and light-intensity hypotheses on larval survival of flathead flounder

  Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))

  Date (from‐to) : 2008 -2011 

  Author : Tetsuya TAKATSU, Yutaka ISODA, Naoto KOBAYASHI

   

  Faster-growing larvae of flathead founder Hippoglossoides dubius in the initial feeding stage showed higher survival rate than slower-growing ones within cohort in Funka Bay, Hokkaido. The larvae of 2007 year-class that experienced warm-water-temperature condition showed the fastest growth in 2007-2011 year-classes. Contrary to expectations, the 2008 year-class that showed slowest-growing in larval stage became a strong year class in mature stage. Growth rate in the initial feeding stage was weakly correlated with wind speed as a turbulence indicator however did not with water temperature, global solar radiation, or density of copepod nauplii as principal prey for flathead founder larvae. Match-mismatch and growth-mortality hypotheses in initial feeding stage have some degree of validity but are insufficient to explain the variability seen in recruitment. The survival in later stage may determine the recruitment success.
• イカナゴ仔魚の餌生物環境と生残仮説の検証

  文部科学省：科学研究費補助金(若手研究(B))

  Date (from‐to) : 2003 -2005 

  Author : 高津 哲也

   

  イカナゴAmmodytes personatusの加入量予測を可能とするために,2003〜2005年に陸奥湾に出現した浮遊仔魚の分布密度,成長様式,成長率と生息環境を評価し,初期生残にかかわる諸仮説を検証した。1,湾口部の産卵場から湾内に輸送されるイカナゴ仔魚の密度は,湾内への津軽暖流水の流入量に依存していた。2,耳石日周輪解析によって求めた仔魚の孵化日組成は,3年間で若干のずれがみられたが,おおむね2月下旬から4月中旬に孵化した個体が多かった。3,摂餌開始期のイカナゴ仔魚の主要餌生物であるカイアシ類ノープリウスと,大型仔魚が捕食するカイアシ類コペポダイトおよび尾虫類は,3年間ともに仔魚が捕食すると考えられる時期には低密度であり,ミスマッチとなっていた。4,本研究における水温範囲(3.9-10.2℃)では,水温が高いほど仔魚の成長率も増加した。また,採集日直前の5日間の耳石の残差成長率も水温と有意な正の相関を示したが(r=0.15,P=0.03),カイアシ類ノープリウスの密度(範囲:13.0-35.0個体・L^<-1>)とは有意な相関はなかった(P=0.55)。5,24日齢以下の仔魚(主に脊索屈曲完了前仔魚)のうち,高成長率個体に偏って多く生残しており,低成長率個体は被食されやすいか,摂餌能力が低いために死亡しやすいものと推定された。陸奥湾におけるイカナゴ浮遊仔魚の生残には,湾内への輸送,高水温によって成長停滞が生じないこと,ボトムアップ効果が働いて餌密度が高まることの3条件をすべて満たす必要があり,いずれが欠けても高い生残率は期待できないことが明らかになった。近年の漁獲量の低下も,低水温化でよく説明できた。
• Analytical Method for Nutirtional Condition of Marine Fish Larvae by Individual

  Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))

  Date (from‐to) : 2003 -2004 

  Author : Yasuhiro ANDO, Tetsuya TAKATSU

   

  A sensitive and convenient procedure for fatty acid analysis of marine fish larvae has been developed in order to determine docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) contents as an indicator of their nutritional condition. Fatty acid content and composition in each individual of the wild marine fish larvae have been analyzed by the new procedure.1.High-performance liquid chromatography (HPLC) of fatty acid 9-anthrylmethyl esters was introduced to the new procedure. Highly sensitive fluorescent detection of the esters enabled the analysis of one eye and somatic part from one individual.2.Some processes of the analysis were modified to reduce time-consuming complicated operations. All processes after lipid extraction could be carried out in a single disposable glass vial. The analysis was completed within 3.5 hours, and about ten samples could be analyzed in one day.3.Somatic part of the 326 individuals of wild fish larvae (18 species) caught in the Funka and Mutsu Bays, Japan, were subjected to the fatty acid analysis. In all individuals, remarkable fatty acids were only five components, DHA (18-32 %), palmitic acid (18-27 %), EPA (4-19 %), octadecenoic acid (7-12 %) and stearic acid (4-23 %).4.DHA contents of the somatic part (μg/individual) were summarized for every nine individuals classified by body lengths. Coefficient of variance (CV) was high in the 2.4-3.1 and 4.4-5.2 mm brown sole (CV 0.6-1.0) and 4.8-6.0 mm Japanese anchovy (CV 0.7-0.9). Pacific sandlance showed generally lower CV (0.2-0.5 with one exception 0.9). The contents of DHA essential for marine fish larvae widely vary at specific stages during development of wild marine fish larvae.
• 複合多点状態計測によるベントス・稚魚分布密度の高精度推定法の開発

  文部科学省：科学研究費補助金(萌芽研究)

  Date (from‐to) : 2003 -2004 

  Author : 木村 修, 高津 哲也, 清水 晋

   

  1.袴形フレームの採集過程ビデオ録画式軽量ソリネット(ソリ部内幅100cm,全長130cm,全高125cm,重量約40kg,抗力約40kg)を設計・試作した。袋網は網口100cm×50cm,全長は400cmで,総ナイロンもじ網(8×8×140経)1脚約3mmである。ナイロンもじ網ならびに網口部補強帆布は柔軟性がないので,網口下部は直接着底する構造ではない。接地性を良くするため,起こしチェーンに捕集網地(ナイロンラッセルもじ網1脚約1mm)をつけた掃底着底具を網口下部に付加した。海底を照明するため,超高輝度白色LED(5W)2個を用いた自動点灯水中ライト(全長11cm×6cmφ,重量360g)を設計・試作した。2.水深100m前後の沖合域で,防水試験と試験撮影を行った。試作水中ライト2灯つけることにより,海底でもシャッター速度1/100s,感度18dBで小型デジタルカメラレコーダに鮮明なカラー映像を録画することができた。底質が泥では泥煙幕に隠れて網口映像を撮影することができなかったが,砂や砂礫では海水の透明度が高く,映像は鮮明であった。3.映像の画像処理系への取り込み,採集効率や距離換算手法を開発した。録画テープに記録されたタイムコードで映像を指定することにより,複数の着底曳網時の画像データを自動取得した。砂礫底での画像から,全長6cm程度の魚類やヒトデ類を容易に判別できたが,エビ類の判別は困難であった。現在,ビデオ画像を合成して,着底曳網した連続海底平面画像を作成中である。この画像から,採集効率,曳網距離の推定が可能になる。4.曳網速度によって,ソリネットの姿勢や接地状況等がどのように変化するか動作試験を実施した。船速を2knotとし,ワイヤー送出・巻き揚げ速度1m/sで投揚網し,ワイヤー送出速度0.5mで曳網した。向かえ潮では着底後にしゃくるような曳網速度の変動が表れ,曳網状態は充分に安定しないこともあったが,総じて着底時も,その後も良好な接地曳網状態を維持した。曳網中,ソリネットは岩礁に乗り上げたが,姿勢を崩すことなく岩礁を乗り越えて着底した。
• Feeding habits of marbled sole larvae and juveniles in the coastal areas of Tsugaru Strait, Hokkaido

  Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))

  Date (from‐to) : 1999 -2001 

  Author : Toyomi TAKAHASHI, Tetsuya TAKATSU, Toshikuni NAKATANI

   

  To clarify the survival strategy of larval and juvenile marbled sole Pleuronectes yokohamae, spatial and temporal distributions, food abundance in environment, feeding strategy, growth pattern, and predation were investigated in the coastal area of Tsugaru Strait.1. A northward-inshore compensatory drift of deeper water in Hakodate Bay was induced by strong wind in March. Larvae would be transported from the offshore spawning ground to the inshore nursery area by this compensatory drift. Eye-migrating larvae settled mainly on 3-15 m depth bottom, and juveniles concentrated at 5m depth.2. Initial foods of larvae were tintinnids and rotifers, and then shifted to copepod nauplii. Feeding success depended on water temperature rather than prey densities. Eye-migrating larvae shifted their main foods from cladocerans to harpacticoids. Low feeding intensity of these larvae would be caused by rapid changes in morphology.3. Biased feeding on adult males of harpacticoids might have been caused by a behavioral difference in harpacticoid sexes. The main food organisms of juveniles (> 30 mm in standard length) changed from harpacticoids to benthic gammarids, cumaceans, tanaidaceans, and polychaetes.4. Larvae and juveniles were swallowed by a shrimp Crangon uritai. The vertical distributions of these two organisms were more overlapped during the cold spring, increasing the opportunists for predation. This phenomenon seemed to be one of the causes of the interannual fluctuation in recruitment.5. In rearing tanks, C. uritai fed on juveniles at night. Relative high abundance of Nipponomysis sp. would restrict and reduce the predation on juveniles by C. uritai in field6. Growth rings in otoliths were validated as daily increments.Large biomass of marbled sole would be sustained in the strong current, due to demersal and adhesive eggs, larval metamorphosis at small size, and warming by Tsugaru Warm Current. Further investigations needed to assess various mortalities quantitatively.
• カレイ・ヒラメ類，タラ類等の海産仔稚魚の初期生活史と生残過程，卓越年級群発生機構の解明

  その他の研究制度

  Date (from‐to) : 1992
• Ecologies of marine-demersal fish eggs, larvae, and juveniles; Mechanisms of occurrences of dominant year classes of fishes.

  The Other Research Programs

  Date (from‐to) : 1992

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• 水産資源・海洋環境研究の最前線「スケトウダラの資源量の変動―1」

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• 水産資源・海洋環境研究の最前線「函館湾・木古内湾のマコガレイの資源量変動―3」

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• 水産資源・海洋環境研究の最前線「函館湾・木古内湾のマコガレイの資源量変動―2」

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• 水産資源・海洋環境研究の最前線「函館湾・木古内湾のマコガレイの資源量変動―1」

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• 水産資源・海洋環境研究の最前線「ソウハチの漁獲量変動―2」

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• 水産資源・海洋環境研究の最前線「ソウハチの漁獲量変動―1」

  Date : 2018/03

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• 水産資源・海洋環境研究の最前線「アカガレイの漁獲量と資源量の変動―1」

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