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研究者情報

マスター

アカウント（マスター）

  • 氏名

    髙津　哲也(タカツ　テツヤ), タカツ　テツヤ

所属（マスター）

  • 水産科学研究院　海洋生物資源科学部門　資源生物学分野

所属（マスター）

  • 水産科学研究院　海洋生物資源科学部門　資源生物学分野

独自項目

syllabus

  • 2021, 資源生物学特論Ⅱ, Advanced Marine Bioresource Science Ⅱ, 修士課程, 水産科学院, 基礎理論，解析手法，科学的記述法，学術的意義，社会的意義
  • 2021, 資源生物学特論Ⅰ, Avanced Marine Bioresource Science Ⅰ, 修士課程, 水産科学院
  • 2021, 教科教育法（水産II）, Teaching Method of School Subjects(Fishery Ⅱ), 学士課程, 教育学部, 資源増殖、海洋漁業、海洋工学、情報通信、水産食品
  • 2021, 沿岸実習Ⅰ, Field Training I, 学士課程, 水産学部, 海洋環境計測機、水中音響計測機、漁具、採集具、沿岸漁業
  • 2021, 沿岸実習Ⅱ, Field Training II, 学士課程, 水産学部, 海洋環境計測機、水中音響計測機、漁具、採集具、沿岸漁業
  • 2021, 海洋生物科学科沿岸実習, Coastal Field Training on Board, 学士課程, 水産学部, 練習船，うしお丸，魚類採集（A;高津哲也教授担当），海生哺乳類目視（B；三谷曜子准教授担当）,海洋環境化学（C；工藤勲教授担当）
  • 2021, 魚類生産生態学, Production Ecology of Fish, 学士課程, 水産学部, 海産魚類、生活史、食性、時空間分布、海洋環境、再生産、数量変動機構、初期生残、漁業活動や人間活動との関連性
  • 2021, 水産資源各論, Introduction of Fisheries Biology, 学士課程, 水産学部, 水産生物，分布，生活史，生態，漁獲方法，資源利用
  • 2021, 海洋生物科学実験Ⅳ, Marine Science Biology IV - Laboratory, 学士課程, 水産学部, 魚類，海生哺乳類，海鳥，多様性，形態，食性
  • 2021, 環境と人間, Environment and People, 学士課程, 全学教育, 海洋物理，海洋化学、海洋生態系，気候変化，プランクトン，ベントス，カレイ，サケ、深海魚、イカ・タコ類，鯨類，海鳥類，海獣類，衛星海洋学，人間活動，地球温暖化，海洋動物の保全・保護

researchmap

プロフィール情報

学位

  • 博士（水産学）（1998年12月 北海道大学）

プロフィール情報

  • プロフィール

    多獲性海産魚類の資源量変動機構を明らかにするために，卵・仔稚魚の生活史を研究しています。

  • 姓

    高津, タカツ

  • 名

    哲也, テツヤ

  • ID各種

    200901066478379535

対象リソース

業績リスト

研究キーワード

  • 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)   

研究分野

  • ライフサイエンス / 水圏生産科学

経歴

  • 2010年04月 Faculty of Fisheries Sciences, Hokkaido Univ. Division of Marine Bioresource and Environmental Science, Laboratory of Marine Bioresource Science Professor
  • 2006年04月 - 2010年03月 Faculty of Fisheries Sciences, Hokkaido Univ. Division of Marine Bioresource and Environmental Science, Laboratory of Marine Bioresource Science Associate Professor
  • 2010年 - 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年04月 - 2006年03月 Graduate School of Fisheries Siences, Hokkaido Univ. Laboratory of Marine Biorecources Ecology Assistant Profeser
  • 1992年07月 - 1995年03月 Faculty of Fisheries, Hokkaido Univ. Laboratory of Principals of Fishing Ground Assistant Profeser
  • 1992年 - 1995年 水産学部 漁業学科 漁場学講座 助手

学歴

  • 1991年04月 - 1992年06月   北海道大学   大学院水産学研究科   博士後期課程
  • 1989年04月 - 1991年03月   北海道大学   大学院水産学研究科   博士前期課程
  • 1988年04月 - 1989年03月   北海道大学   水産学部   特設専攻科
  • 1984年04月 - 1988年03月   北海道大学   水産学部   漁業学科

委員歴

  • 2023年08月 - 現在   北海道渡島海区漁業調整委員会   委員
  • 2023年03月 - 現在   Fisheries Oceanography誌副編集長
  • 2020年04月 - 現在   日本水産学会   北海道支部幹事
  • 2018年04月 - 現在   水産増殖学会   幹事
  • 2018年03月 - 現在   水産海洋学会   理事
  • 2021年05月 - 2024年03月   日本水産増殖学会   副会長
  • 2021年05月 - 2023年03月   水産海洋学会   編集委員会委員長
  • 2013年04月 - 2019年08月   日本水産学会   編集委員
  • 2013年04月 - 2017年03月   水産海洋学会   編集委員
  • 2008年   日本水産学会   北海道支部庶務幹事（2008年度）   日本水産学会
  • 1995年04月 - 1996年03月   日本水産学会   北海道支部庶務幹事（1995年度）   日本水産学会

受賞

  • 2018年03月 水産海洋学会 第23回宇田賞
     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 
    受賞者: 高津 哲也
  • 2017年06月 Fisheries Oceanography, Wiley Reviewer Award of Fisheries Oceanography (14 manuscripts in 2016)
     
    受賞者: 高津 哲也
  • 2015年03月 北海道大学 「平成26年度北海道大学教育総長賞，奨励賞」（4,全学的教育への貢献度の高い教員）
     
    受賞者: 高津 哲也
  • 2012年03月 日本プランクトン学会 第10回日本プランクトン学会論文賞
     噴火湾におけるアカガレイおよびイシガレイ仔魚の食性－尾虫類Oikopleuraの餌生物としての重要性 
    受賞者: 橋本雄太郎;前田晃子;大野雄介;鹿野陽太;髙津哲也
  • 2003年 平成14年度日本水産学会奨励賞
  • 2003年 Achievement Award for Young Scientist: The Japanese Society of Fisheries Science Awards 2002
  • 2000年 パイセス第９回年次総会(PICES IX)ベストポスター賞
  • 2000年 North Pacific Marine Science Organization, 9th Annual Meeting; Best Poster Award

論文

  • Tomoya Ishikawa, Mitsuhiro Nakaya, Yuta Eno, Tetsuya Takatsu
    J Fish Biol 2024年07月 [査読有り][通常論文]
  • Tetsuya Takatsu, Tomoaki Toyonaga, Shin’ya Hirao, Eri Ooka, Naoto Kobayashi, Mitsuhiro Nakaya
    Fisheries Science 90 3 435 - 452 2024年04月 [査読有り][通常論文]
  • Yue Dong, Yixuan Li, Meiling Ge, Tetsuya Takatsu, Zongling Wang, Xuelei Zhang, Dewen Ding, Qinzeng Xu
    Microbiology Spectrum 11 6 2023年12月12日 [査読有り]
     
    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.
  • Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu, Atsushi Ooki
    Biogeosciences 20 2 421 - 438 2023年01月27日 
    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.
  • 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 2023年01月09日 [査読有り]
  • Takumi Teraoka, Kanako Amei, Yutaka Fukai, Kohei Matsuno, Hiroji Onishi, Atsushi Ooki, Tetsuya Takatsu, Atsushi Yamaguchi
    Plankton and Benthos Research 17 4 369 - 382 2022年11月30日
  • Atsushi Ooki, Keita Minamikawa, Fanxing Meng, Naoya Miyashita, Toru Hirawake, Hiromichi Ueno, Yuichi Nosaka, Tetsuya Takatsu
    Communications Earth & Environment 3 1 2022年08月12日 [査読有り][通常論文]
     
    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.
  • Tomoya Ishikawa, Mitsuhiro Nakaya, Weifeng Gao, Tetsuya Takatsu, Kenji Odani, Ryo Suzuki, Kyosei Noro, Yuhei Takeya
    Environmental Biology of Fishes 105 2 303 - 312 2022年02月 [査読有り][通常論文]
  • Keitaro Kajiwara, Mitsuhiro Nakaya, Kota Suzuki, Yota Kano, Tetsuya Takatsu
    Fisheries Oceanography 31 3 238 - 254 2022年02月 [査読有り][通常論文]
  • Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu, Atsushi Ooki
    2022年01月06日 [査読有り]
     
    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.
  • Atsushi Ooki, Naoya Miyashita, Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu
    GEOCHEMICAL JOURNAL 56 5 142 - 150 2022年 [査読有り][通常論文]
  • Tomoya Ishikawa, Mitsuhiro Nakaya, Tetsuya Takatsu
    Environmental Biology of Fishes 105 1 77 - 86 2022年01月 [査読有り][通常論文]
  • Tran Nguyen Hai NAM, Mitsuhiro NAKAYA, Tomoya ISHIKAWA, Tetsuya TAKATSU
    Aquaculture Science 2021 3 223 - 225 2021年10月 [査読有り][通常論文]
  • Obata Kota, Kawai Toshio, Takatsu Tetsuya
    Bulletin of Fisheries Sciences, Hokkaido University 71 1 15 - 20 2021年08月 [査読無し]
  • Tran Nguyen Hai NAM, Mitsuhiro NAKAYA, Tetsuya TAKATSU
    Aquaculture Science 2021 2 153 - 161 2021年07月 [査読有り][通常論文]
  • Weifeng Gao, Mitsuhiro Nakaya, Tomoya Ishikawa, Tetsuya Takatsu, Yuhei Takeya, Ryo Suzuki, Kyosei Noro
    Fisheries Science 87 4 541 - 548 2021年07月 [査読有り][通常論文]
  • 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 2019年12月 [査読有り][通常論文]
  • Hideyoshi Yamaoka, Tetsuya Takatsu, Kota Suzuki, Naoto Kobayashi, Atsushi Ooki, Mitsuhiro Nakaya
    Fisheries Science 85 6 1077 - 1087 2019年09月 [査読有り][通常論文]
  • 髙津 哲也
    水産海洋研究 83 3 191 - 196 2019年08月 [査読無し][招待有り]
  • 折野和樹, 石金晃介, 鈴木孝太, 泉浦裕基, 中屋光裕, 髙津哲也
    Fisheries Science 85 4 705 - 716 2019年08月 [査読有り][通常論文]
     
    噴火湾で採集されたキタクシノハクモヒトデの腕骨表面の隆起線を用いた年齢査定法を確立し，成長式を求めた。ソリネット採集個体の縁辺成長率の月変化より，隆起線の年1本の形成を確認した。体盤径と隆起線数の間にはRichard式が良く当てはまった。体盤径<9mmと15mm前後のコホートは複数の年級群から構成され，後者は低成長率・低生残率によって生じると推定された。
  • 山本佑樹, 池田 実, 中屋光裕, 鈴木孝太, 髙津哲也
    魚類学雑誌 65 1 75 - 80 2018年04月 [査読有り][通常論文]
     
    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.
  • 竹谷 裕平, 髙津 哲也, 山中 智之, 柴田 泰宙, 中屋 光裕
    日本水産学会誌 84 1 130 - 132 2018年 [査読有り][通常論文]
  • Savitri Marannu, Mitsuhiro Nakaya, Tetsuya Takatsu, Shin-ichi Takabatake, Mikimasa Joh, Yutaro Suzuki
    FISHERIES RESEARCH 194 129 - 134 2017年10月 [査読有り][通常論文]
     
    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.
  • Mitsuhiro Nakaya, Yuhei Takeya, Ryo Suzuki, Kyosei Noro, Weifeng Gao, Tetsuya Takatsu
    Aquaculture Science 65 3 251 - 254 日本水産増殖学会 2017年09月 [査読有り][通常論文]
  • Mitsuhiro Nakaya, Savitri Marannu, Yuta Inagaki, Keitaro Kajiwara, Yoshitaka Sato, Kota Suzuki, Tetsuya Takatsu
    Aquaculture Science 65 3 247 - 250 日本水産増殖学会 2017年09月 [査読有り][通常論文]
  • 鈴木 孝太, 中屋 光裕, 柳 海均, 松田 泰平, 髙津 哲也
    日本水産学会誌 83 4 580 - 588 公益社団法人 日本水産学会 2017年07月 [査読有り][通常論文]
     
    <p> アカガレイ卵・仔魚の輸送過程を明らかにする端緒として，飼育実験で，卵・仔稚魚の発生・発育に伴う比重変化の測定および卵発生速度と水温（1-12℃）の関係を調べた。卵の比重は，生息域である噴火湾の海水密度より常に低く，浮上したが，卵黄嚢仔魚では逆転した。屈曲前前期の仔魚の比重は海水密度とほぼ同等になり，それ以降は発育とともに再び高比重になった。水温1-12℃において，卵および卵黄嚢仔魚期の日数は高水温ほど短かった。水温や生息水深別の流向・流速の年較差が卵・仔魚の輸送過程を変化させている可能性が示唆された。</p>
  • 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 2017年06月 [査読有り][通常論文]
     
    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).
  • Nobuaki Nanjo, Tetsuya Takatsu, Kazuo Imura, Kingo Itoh, Yuuhei Takeya, Toyomi Takahashi
    FISHERIES SCIENCE 83 2 199 - 214 2017年03月 [査読有り][通常論文]
     
    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.
  • 竹谷 裕平, 髙津 哲也, 山中 智之, 柴田 泰宙, 中屋 光裕
    日本水産学会誌 83 1 9 - 17 公益社団法人 日本水産学会 2017年 [査読有り][通常論文]
     
    <p> 青森県周辺海域におけるキアンコウの背鰭第一棘による年齢査定法を検証した。背鰭第一棘の付け根付近の横断面をエッチング処理した後，メチレンブルーで染色し，実体顕微鏡下で落射光と透過光の両者による比較観察した結果，不透明帯数の読み取り精度が向上した。同横断面には，1年に2本の不透明帯（主に6月と11-12月）が形成されていた。背鰭第一棘による年齢査定は脊椎骨によるものよりも読み取り誤差が小さく，標識放流魚の成長追跡結果と類似したことから，優れた年齢査定法と判定した。</p>
  • 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 2015年12月 [査読有り][通常論文]
     
    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.
  • Yuta Inagaki, Tetsuya Takatsu, Takao Uenoyama, Noriko Yoneda, Shinichi Yokoyama, Yoshihiko Kamei, Naoto Kobayashi, Toyomi Takahashi
    FISHERIES SCIENCE 81 4 687 - 698 2015年07月 [査読有り][通常論文]
     
    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.
  • Yota Kano, Tetsuya Takatsu, Yutaro Hashimoto, Yuta Inagaki, Toshikuni Nakatani
    FISHERIES OCEANOGRAPHY 24 4 325 - 334 2015年07月 [査読有り][通常論文]
     
    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.
  • Yuki Kobayashi, Tetsuya Takatsu, Hiroshi Yamaguchi, Mikimasa Joh
    FISHERIES SCIENCE 81 3 463 - 472 2015年05月 [査読有り][通常論文]
     
    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.
  • 甲本亮太, 高津哲也
    秋田県水産振興センター研究報告書 1 1 1 - 8 2015年03月 [査読無し][通常論文]
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  • Hideharu Tsukagoshi, Keishi Takeda, Tomoko Kariya, Takuma Ozaki, Tetsuya Takatsu, Syuiti Abe
    BIOCHEMICAL SYSTEMATICS AND ECOLOGY 58 274 - 280 2015年02月 [査読有り][通常論文]
     
    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.
  • 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 90 1 11 - 16 海洋気象学会 2014年08月31日 [査読有り][通常論文]
  • Yuta Inagaki, Tetsuya Takatsu, Masafumi Kimura, Yota Kano, Toyomi Takahashi, Yoshihiko Kamei, Naoto Kobayashi, Tatsuaki Maeda
    FISHERIES SCIENCE 80 4 725 - 734 2014年07月 [査読有り][通常論文]
     
    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.
  • Yuko Hiraoka, Tetsuya Takatsu, Yasuhiro Ando
    MARINE BIOLOGY 161 7 1615 - 1625 2014年07月 [査読有り][通常論文]
     
    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.
  • 小林直人, 磯田 豊, 高津哲也, 木村 修, 亀井佳彦
    海と空 88 3 57 - 63 海洋気象学会 2013年03月22日 [査読有り][通常論文]
  • Mikimasa Joh, Mitsuhiro Nakaya, Naoto Yoshida, Tetsuya Takatsu
    MARINE ECOLOGY PROGRESS SERIES 494 267 - 279 2013年 [査読有り][通常論文]
     
    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.
  • 岩川浩大, 高橋豊美, 髙津哲也, 稲垣祐太, 中谷敏邦, 前田辰昭
    日本水産学会誌 79 1 10 - 19 2013年01月 [査読有り][通常論文]
     
    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.
  • 小林直人, 磯田 豊, 高津哲也, 木村 修, 亀井佳彦
    海と空 88 2 43 - 48 海洋気象学会 2012年11月30日 [査読有り][通常論文]
  • 敷島 良也, 高津 哲也, 高橋 豊美, 二宮 正光, 坂井 伸司, 一ノ瀬 寛之, 森岡 泰三, 佐々木 正義
    日本水産学会誌 = Nippon Suisan Gakkaishi 78 6 1170 - 1175 日本水産學會 2012年11月 [査読有り][通常論文]
     
    えりも岬以東海域で刺網と定置網，桁網で採集したマツカワの成長特性を明らかにした。無眼側耳石の外縁は，4～7 月には不透明帯を持つ個体の割合が増加し，8～12 月には減少していた。透明帯外縁を指標として年齢群に分けたところ，夏季に全長が著しく増加したが，11～5 月にはほとんど成長しないことが判った。4 月 1 日を年齢起算日とし，全長を von Bertalanffy 式に当てはめた。えりも岬以西海域に比べて本海域の方が成長が速い要因として，夏季に成長に適した 20℃ 以下の水温に保たれることが考えられた。<br>
  • 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, アナ・ルイザ・ロザ
    海と空 88 1 9 - 20 海洋気象学会 2012年07月 [査読有り][通常論文]
  • Yuta Inagaki, Tetsuya Takatsu, Yuki Ashida, Toyomi Takahashi
    FISHERIES SCIENCE 78 3 647 - 659 2012年05月 [査読有り][通常論文]
     
    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.
  • 工藤充弘, 髙津哲也, 福井翔太郎, 甲本亮太
    魚類学雑誌 59 1 21 - 35 日本魚學振興會 2012年04月25日 [査読有り][通常論文]
     
    陸奥湾にはハタハタ成魚は分布しないにもかかわらず稚魚が生息する年があることを示し,その孵化日組成や耳石輪紋幅を明らかにすることで,稚魚の起源と陸奥湾への輸送過程,成長履歴を検討し,本種の生活史特性を解明することを目的とした。
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  • 甲本亮太, 工藤裕紀, 高津哲也
    水産増殖 59 4 615 - 630 2011年12月 [査読有り][通常論文]
  • 橋本雄太郎, 前田晃子, 大野雄介, 鹿野陽太, 高津哲也
    日本プランクトン学会報 58 2 165 - 177 日本プランクトン学会 2011年08月 [査読有り][通常論文]
  • 米田典子, 高橋豊美, 高津哲也
    水産増殖 58 1 1 - 16 水産増殖談話会 2010年03月 [査読有り][通常論文]
     
    ヒレグロの資源維持および増強を目的に，2006年4月～2007年3月に北海道噴火湾から採集した個体の耳石による年齢査定を行い，漁獲時の年齢－体長データに基づいて成長解析を行った。耳石の不透明帯外縁は主に8～9月に形成される年周輪であり，この時期は孵化盛期とほぼ一致した。t（歳）時の体長をSLt（mm）とすると，成長式は雌でSLt = 393.1 [1－exp {－0.145 (t+0.081)}]，雄でSLt = 393.1 [1－exp {－0.134 (t+0.088)}]と表された。噴火湾のヒレグロは山陰沖に比べて1歳時以降の成長速度が速く，この地域差には餌利用可能度が関与している可能性が考えられた。
  • 平岡優子, 高津哲也, 大野雄介, 奥村裕弥, 高橋英昭, 高橋豊美
    水産海洋研究 73 2 90 - 101 2009年08月 [査読有り][通常論文]
  • Mikimasa Joh, Tetsuya Takatsu, Mitsuhiro Nakaya, Naoto Yoshida, Masayasu Nakagami
    FISHERIES SCIENCE 75 3 619 - 628 2009年05月 [査読有り][通常論文]
     
    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.
  • 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
    北大水産彙報 58 3 29 - 41 北海道大学大学院水産科学研究院 = Research Faculty of Fisheries Sciences, Hokkaido University 2009年02月 [査読無し][通常論文]
     
    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).
  • Mikimasa JOH, Takashi JOH, Teppei MATSU-URA, Tetsuya TAKATSU
    Aquaculture Science 56 2 157 - 166 水産増殖談話会 2008年06月 [査読有り][通常論文]
     
    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。
  • 山内務巨, 濱津友紀, 大村敏昭, 高津哲也, 高橋豊美
    北大水産彙報 58 1/2 11 - 19 北海道大学大学院水産科学研究院 = RESEARCH FACULTY OF FISHERIES SCIENCES, HOKKAIDO UNIVERSITY 2008年05月 [査読無し][通常論文]
     
    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.
  • Yasuhiro Ando, Yusuke Haba, Kazutaka Soma, Yuko Hiraoka, Tetsuya Takatsu
    LIPIDS 42 10 955 - 960 2007年10月 [査読有り][通常論文]
     
    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.
  • Tomomi Higashitani, Tetsuya Takatsu, Mitsuhiro Nakaya, Mikimasa Joh, Toyomi Takahashi
    JOURNAL OF SEA RESEARCH 58 1 78 - 89 2007年07月 [査読有り][通常論文]
     
    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.
  • Mitsuhiro Nakaya, Tetsuya Takatsu, Mikimasa Joh, Masayasu Nakagami, Toyomi Takahashi
    FISHERIES SCIENCE 73 1 112 - 122 2007年02月 [査読有り][通常論文]
     
    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.
  • Tetsuya Takatsu, Yuusuke Suzuki, Akiko Shimizu, Kazuo Imura, Yuko Hiraoka, Naonobu Shiga
    FISHERIES SCIENCE 73 1 142 - 155 2007年02月 [査読有り][通常論文]
     
    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.
  • Tetsuya TAKATSU
    NIPPON SUISAN GAKKAISHI 2006年
  • 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 69 3 145 - 155 水産海洋学会 2005年08月 [査読有り][通常論文]
  • M Joh, T Takatsu, M Nakaya, T Higashitani, T Takahashi
    MARINE BIOLOGY 147 1 59 - 69 2005年05月 [査読有り][通常論文]
     
    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.
  • 吉田直人, 高津哲也, 中屋光裕, 城幹昌, 木村修, 清水晋
    日本水産学会誌 71 2 172 - 177 2005年03月 [査読有り][通常論文]
     
    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.
  • Yuko Hiraoka, Tetsuya Takatsu, Akiko Kurifuji, Kazuo Imura, Toyomi Takahashi
    Bull. Jpn. Soc. Fish. Oceanogr. 69 3 156 - 164 水産海洋学会 = Japanese Society of Fisheries Oceanography 2005年 [査読有り][通常論文]
     
    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。
  • Tetsuya TAKATSU
    NIPPON SUISAN GAKKAISHI 2005年
  • M.M. Shafieipour, T. Takahashi, K. Ishino, Y. Konno, H. Nakao, M. Sano, O. Tominaga, T. Takatsu
    Aquaculture Science 52 2 351 - 358 水産増殖談話会 2004年12月 [査読有り][通常論文]
     
    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。
  • 小林直人, 磯田豊, 高津哲也, 山口秀一, 木村修
    北大水産彙報 55 2 97 - 103 北海道大学 2004年10月 [査読無し][通常論文]
  • 高津 哲也
    月刊海洋 36 10 761 - 765 海洋出版 2004年10月 [査読無し][通常論文]
  • M Kimura, T Takahashi, T Takatsu, T Nakatani, T Maeda
    FISHERIES SCIENCE 70 4 537 - 545 2004年08月 [査読有り][通常論文]
     
    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.
  • Mitsuhiro Nakaya, Tetsuya Takatsu, Masayasu Nakagami, Mikimasa Joh, Toyomi Takahashi
    Fisheries Science 70 3 445 - 455 2004年06月 [査読有り][通常論文]
     
    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.
  • 伊村一雄, 高津哲也, 南條暢聡, 木村修, 高橋豊美
    日本水産学会誌 70 1 39 - 47 2004年01月 [査読有り][通常論文]
     
    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.
  • NAKAYA Mitsuhiro, TAKATSU Tetsuya, NAKAGAMI Masayasu, JOH Mikimasa, TAKAHASHI Toyomi
    Aquaculture Science 52 2 121 - 128 日本水産増殖学会 2004年 [査読有り][通常論文]
     
    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>.
  • 長谷川藍, 高津哲也, 伊村一雄, 南条暢聡, 高橋豊美
    日本水産学会誌 69 6 940 - 947 The Japanese Society of Fisheries Science 2003年11月 [査読有り][通常論文]
     
    99年と2001年の5-6月にプランクトンネットで採集されたヒラメ仔魚は,摂餌関始期には主に有鐘繊毛虫類とかいあし類ノープリウス(主にparacalanus属),尾虫類を摂餌し,大型仔魚は尾虫類とコペポダイトを摂餌した。摂餌開始仔魚のノープリウス摂餌率は1999年(16%)よりも2001年(55%)に高かった。環境中のParacalanus属ノープリウスの体積豊度は1999年よりも2001年の方が1.2-2.0倍高く,仔魚も相対的に入っていた。摂餌関始期のヒラメ仔魚の摂餌強度や栄養状態は,環境中のノープリウス豊度の変動に影響を受けやすい。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.
  • 城 幹昌, 高津 哲也, 中屋 光裕, ほか
    水産増殖 51 2 227 - 228 水産増殖談話会 2003年06月 [査読有り][通常論文]
     
    ホルムアルデヒド、エタノール、カレイ類、保存、体長、収縮。
  • T Sekigawa, T Takahashi, T Takatsu, S Nishiuchi, M Sasaki, F Shiokawa
    FISHERIES SCIENCE 69 3 575 - 580 2003年06月 [査読有り][通常論文]
     
    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.
  • 関河武史, 高橋豊美, 高津哲也, 桜井泰憲
    日本水産学会誌 69 3 380 - 386 2003年05月 [査読有り][通常論文]
     
    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.
  • 中谷 敏邦, 杉本 晃一, 高津 哲也, 高橋 豊美
    水産海洋研究 67 1 23 - 28 水産海洋学会 2003年02月 [査読有り][通常論文]
     
    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。
  • 関河武史, 高橋豊美, 高津哲也
    Aquacult. Sci. 50 4 395 - 400 水産増殖談話会 2002年12月 [査読有り][通常論文]
     
    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。
  • T. Nakatani, T. Maeda, K. Sugimoto, T. Takatsu, T. Takahashi
    Bull. Jpn. Soc. Fish. Oceanogr. 66 4 216 - 223 2002年12月 [査読有り][通常論文]
  • K Kooka, D Yanagida, Y Suzuki, S Ohsaki, T Takatsu
    FISHERIES SCIENCE 68 4 951 - 953 2002年08月 [査読有り][通常論文]
  • T Takatsu, T Nakatani, T Miyamoto, K Kooka, T Takahashi
    FISHERIES OCEANOGRAPHY 11 2 90 - 101 2002年03月 [査読有り][通常論文]
     
    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.
  • 中神正康, 高津哲也, 中屋光裕, 高橋豊美
    水産海洋研究 65 3 85 - 93 2001年08月 [査読有り][通常論文]
  • J.-S. Ho, K. Nagasawa, T. Takatsu
    Bull. Fish. Sci. Hokkaido Univ. 52 1 1 - 3 北海道大学 2001年03月 [査読無し][通常論文]
  • T. Takatsu, Y. Yoshida, K. Kooka, K. Sugimoto, T. Takahashi
    Bull. Jpn. Soc. Fish. Oceanogr. 65 1 6 - 14 水産海洋学会 = Japanese Society of Fisheries Oceanography 2001年02月 [査読有り][通常論文]
     
    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．
  • Tetsuya TAKATSU
    Bull. Fac. Fish. Hokkaido Univ. 51 2 51 - 56 2000年09月 [査読無し][通常論文]
  • 中神正康, 高津哲也, 松田泰平, 高橋豊美
    日本水産学会誌 66 5 818 - 824 The Japanese Society of Fisheries Science 2000年09月 [査読有り][通常論文]
     
    マコガレイ稚魚の主要餌生物の変化とハルパクチクス目の雄成体に偏った捕食を検討した。1996年5-7月, 1997年5月の岩部漁港ではハルパクチクス目のHarpacticus sp.が多く捕食されていた, 1997年5月の七重浜沖ではHalectinosoma sp.が主に捕食されていた。1996年8月以降体長30mmを超えると主要餌生物は, 小型底生甲殻類や多毛類に変化した。ハルパクチクス目の雄成体に偏った捕食は, サイズ選択ではなく繁殖期に雄の行動が活発化し, 捕食され易くなった結果と考えられた。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 (&le;30mm in SL) fed on harpacticoid copepods, mainly Harpacticus sp. Off Nanaehama Beach in May 1997,juveniles preyed on harpacticoids, mainly Halectinosoma sp. In August, the main food organisms of juveniles (>30mm in SL) changed from harpacticoids to small benthic crustaceans and polychaetes. In 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. In 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.
  • T. Takatsu, S. Takagi, S. Yokoyama, T. Takahashi
    Bull. Fac. Fish. Hokkaido Univ. 50 3 155 - 169 1999年09月 [査読無し][通常論文]
  • 高津哲也, 小岡孝治
    東北底魚研究 19 92 - 95 1999年07月 [査読無し][通常論文]
  • 亀井佳彦, 高津哲也, 高木省吾, 中谷敏邦, 高橋豊美, 前田辰昭
    日本水産学会誌 65 2 223 - 229 1999年03月 [査読有り][通常論文]
     
    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.
  • M. M. Shafieipour, T. Takahashi, K. Ishino, T. Takatsu, T. Nakatani
    Iranian J. Fisheries Sci. 1 1 5 - 21 1999年 [査読有り][通常論文]
  • K Kooka, T Takatsu, Y Kamei, T Nakatani, T Takahashi
    FISHERIES SCIENCE 64 5 686 - 693 1998年10月 [査読有り][通常論文]
     
    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.
  • 小岡孝治, 高津哲也, 亀井佳彦, 中谷敏邦, 高橋豊美
    日本水産学会誌 63 4 537 - 541 1997年07月 [査読有り][通常論文]
     
    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.
  • 井口謙, 中谷敏邦, 高津哲也, 高橋豊美
    日本水産学会誌 63 1 50 - 55 1997年01月 [査読有り][通常論文]
     
    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.
  • 高木省吾, 前田辰昭, 亀井佳彦, 中谷敏邦, 高津哲也, 高橋豊美
    日本水産学会誌 62 2 205 - 212 1996年03月 [査読有り][通常論文]
     
    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.
  • T Takahashi, Y Hayakawa, T Kamiharako, T Nakatani, T Takatsu
    FISHERIES SCIENCE 61 6 893 - 897 1995年12月 [査読有り][通常論文]
     
    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.
  • 筒井 浩之, 中谷 敏邦, 高津 哲也, 高橋 豊美
    日本水産学会誌 61 5 707 - 712 日本水産學會 1995年09月 [査読有り][通常論文]
     
    Gonadal maturation of female ribbon prickleback, <i>Lumpenus sagitta</i>, 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 <i>L. sagitta</i> 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, 91.6% 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 Novemver, many oocytes at the migratory nucleus stage were observed. These observations, indicate that <i>L. sagitta</i> spawn from December to January in Funka Bay.
  • T TAKATSU, T NAKATANI, T MUTOH, T TAKAHASHI
    FISHERIES SCIENCE 61 3 415 - 422 1995年06月 [査読有り][通常論文]
     
    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.
  • 宮本孝則, 高津哲也, 中谷敏邦, 前田辰昭, 高橋豊美
    水産海洋研究 57 1 1 - 14 水産海洋学会 = Japanese Society of Fisheries Oceanography 1993年02月 [査読有り][通常論文]
     
    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.
  • 高津 哲也, 高橋 豊美, 中谷 敏邦, 前田 辰昭, 大越 金蔵
    日本水産学会誌 58 12 2235 - 2243 日本水産學會 1992年12月 [査読有り][通常論文]
     
    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°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 tem-perature at the surface rose to 10.9-12.7°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.
  • 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 56 4 426 - 432 水産海洋学会 = Japanese Society of Fisheries Oceanography 1992年12月 [査読有り][通常論文]
     
    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

書籍等出版物

  • 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 (範囲: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年10月 (ISBN: 9784303800116) 97p
  • 髙津, 哲也 (担当:単著)
    海文堂出版 2022年03月 (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 (担当:共著範囲:魚類・ベントス測定)
    海文堂出版 2019年07月
  • 公益財団法人北水協会移行記念誌
    高津 哲也 (担当:分担執筆範囲:北水協会の教育貢献)
    公益財団法人北水協会 2011年
  • 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年

講演・口頭発表等

所属学協会

  • 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   

共同研究・競争的資金等の研究課題

  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2024年04月 -2028年03月 
    代表者 : 高津 哲也
  • 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
    研究期間 : 2011年04月 -2025年03月 
    代表者 : 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
  • 日本学術振興会：科学研究費助成事業 基盤研究(C)
    研究期間 : 2021年04月 -2024年03月 
    代表者 : 高津 哲也, 中屋 光裕
     
    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。
  • 日本学術振興会：科学研究費助成事業 基盤研究(C)
    研究期間 : 2016年04月 -2019年03月 
    代表者 : 高津 哲也, 中屋 光裕
     
    スケトウダラの初期生残過程を解明するために、母親効果と卵仔稚魚の栄養状態を検証した。2016-2018年級群の仔魚のふ化輪紋径には差が小さかったことから、雌親魚の年齢に由来するふ化サイズ依存的生残の年変動は検出できなかった。2月下旬から3月上旬の仔魚の体長は、低水温年ほど小型だった。6月中旬の着底稚魚の75-77%には耳石に着底輪が認められ、平均着底尾叉長は67.2-69.0mmと推定された。津軽暖流が流入して水温が上昇した8-10月には、稚魚の摂餌強度と栄養状態が低下し、その後水温低下とともに回復した。湾内で越冬する稚魚は、栄養状態と成長速度に年変動があり、加入量に影響を及ぼすと考えられた。
  • 文部科学省：科学研究費補助金(基盤研究(C))
    研究期間 : 2013年 -2015年 
    代表者 : 高津 哲也
     
    噴火湾においてアカガレイ仔稚魚の輸送・着底過程を検証した。2013年5月のFMTネットでは、浮遊期後半の仔魚が室蘭周辺海域で採集されたが、2014-2015年には採集されなかった。2013年級群はその後強勢年級群となったため、北西の季節風によって発達し、大型浮遊仔魚の取り込んだ室蘭沖の時計回りの渦の消長が加入量変動を生じさせていることが考えられた。一方、2013-2015年8-11月の着底トロールネットでは、着底稚魚は採集できず、着底場所は特定できなかった。
  • 文部科学省：科学研究費補助金(基盤研究(C))
    研究期間 : 2008年 -2011年 
    代表者 : 高津 哲也, 磯田 豊, 小林 直人
     
    アカガレイ仔魚は,孵化直後から継続的に成長の速い個体ほど生残しやすい傾向を示し,2007-2011年級群のうち,2007年級群は高水温を経験し成長率が高かった。しかし最も成長率が低かった2008年級群がその後卓越年級群となった。成長率は全体として乱流強度の指標となる風速が増すとわずかに高くなっていたが,餌であるかいあし類ノープリウスの密度や水温,全天日射量とは明瞭な関係はみられなかった。卓越年級群の発生は,摂餌開始期の摂餌の成否や成長率よりもむしろ,浮遊期以後の生残過程によって強く影響を受けているのかもしれない。
  • 文部科学省：科学研究費補助金(若手研究(B))
    研究期間 : 2003年 -2005年 
    代表者 : 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。
  • 文部科学省：科学研究費補助金(基盤研究(C))
    研究期間 : 2003年 -2004年 
    代表者 : 安藤 靖浩, 高津 哲也
     
    海産仔稚魚に含まれる必須脂肪酸成分(DHA,EPA)を1個体ごとに高感度かつ簡便に分析する手法を確立し,これを天然仔稚魚の分析に適用して脂肪酸成分の個体差の特徴を捉えた。1.高安定蛍光検出器を導入して高速液体クロマトグラフィー(HPLC)による脂肪酸分析の微量化を行った。この高感度分析により,体長が数mmの仔稚魚1個体の体幹部,眼部(1個)の脂肪酸分析が可能となった。2.脂質の抽出,反応,回収の過程を極力簡略化して分析の迅速化を行った。脂質抽出以後の過程は一本の使い捨てガラスバイアル中で実施可能となった。ひとつの分析に要する時間はHPLCを含めて約3.5時間,多検体を同時に分析する場合は1日当たり約10検体の処理が可能であった。3.噴火湾および陸奥湾で採集した18魚種326個体の仔稚魚の体幹部(消化管・卵嚢を除く)の脂肪酸分析を実施した。仔稚魚の主要脂肪酸はすべての個体に共通してDHA(18-32%),パルミチン酸(18-27%),EPA(4-19%),オクタデセン酸(7-12%),ステアリン酸(4-23%)の5種類であることが明らかとなった。4.上記の仔稚魚のDHA含有量(μg/個体)を算出し,仔稚魚を体長に応じて9個体ずつ分級した場合の変動係数(CV)を比較した。その結果,高い変動係数が2.4-3.1mmおよび4.4-5.2mmのマガレイ(CV0.6-1.0),4.8-6.0mmのカタクチイワシ(CV0.7-0.9)で認められた。また,イカナゴでは5.1mmのクラスを除いて全体的に低い値(CV0.2-0.5)であった。天然仔稚魚のDHA含有量は個体差が常に一定であるわけではなく,その差の大きくなる特定の発育段階があることが明らかとなった。
  • 文部科学省：科学研究費補助金(萌芽研究)
    研究期間 : 2003年 -2004年 
    代表者 : 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。
  • 文部科学省：科学研究費補助金(基盤研究(C))
    研究期間 : 1999年 -2001年 
    代表者 : 高橋 豊美, 高津 哲也, 中谷 敏邦
     
    マコガレイPleuronectes yokohamaeの生息北限にあたる北海道津軽海峡沿岸域において,仔稚魚の分布,餌生物環境,摂餌戦略,成長様式,被食を明らかにし,初期生残戦略の概要を解明した。1.浮遊仔魚は,函館湾湾口部の産卵場から沿岸の成育場に,季節風によって生じる吹送流の底層補償流によって輸送される。眼球移動仔魚は水深3-15mの海底に着底し,稚魚は水深5m前後まで接岸する。2.仔魚は主に有鐘繊毛虫類とワムシ類を,その後発育に伴ってかいあし類ノープリウスを捕食した。仔魚の捕食の成否は,餌密度よりも低水温による影響のほうが大きく,7.5℃は本種の再生産の北限を規定する水温と推定した。海底付近に分布する眼球移動仔魚は枝角目から底生性かいあし類ハルパクチクス目へと転換した。眼球移動中には,急速な形態変化に伴って捕食能力が低下した。3.稚魚は,交尾のために活発に動き回り目立ちやすいハルパクチクス目の雄を偏食した。標準体長30mmを超える稚魚は,ヨコエビ亜目,クーマ目,タナイス目などの小型底生性甲殻類や,多毛類を捕食した。4.仔稚魚は着底直後にエビジャコCrangon uritaiによって被食され,水温によって駆動される両者の時空間分布の重複が生残率の年変動に関与しているものと考えられる。5.エビジャコは主に夜間に稚魚を捕食し,稚魚よりも餌料価値の高いアミ目の密度によって,稚魚に対する捕食圧が大きく変化することが予想された。6.仔稚魚の扁平石と礫石の輪紋が日周輪であることを確認した。比較的流速の速い当海域で,マコガレイの生物量が高い理由は,沈性粘着卵,小型での変態の完了,津軽暖流による高水温にあると結論付けた。マコガレイの初期減耗要因は多様であり、いずれの要因が強く働くのか、今後とも継続して検討する必要がある。
  • その他の研究制度
    研究期間 : 1992年
  • Ecologies of marine-demersal fish eggs, larvae, and juveniles; Mechanisms of occurrences of dominant year classes of fishes.
    The Other Research Programs
    研究期間 : 1992年

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