研究者データベース

高木 力(タカギ ツトム)
水産科学研究院 海洋生物資源科学部門 水産工学分野
教授

基本情報

所属

  • 水産科学研究院 海洋生物資源科学部門 水産工学分野

職名

  • 教授

学位

  • 博士(水産学)(北海道大学)

J-Global ID

研究キーワード

  • バイオメカニクス   水産流体力学   水産工学   水産物理学   Fisheries Fluid Dynamics   Fisheries Engineering   

研究分野

  • ライフサイエンス / 水圏生産科学
  • ライフサイエンス / 生態学、環境学
  • フロンティア(航空・船舶) / 船舶海洋工学

職歴

  • 2014年09月 - 現在 北海道大学 大学院水産科学研究院 教授
  • 1999年04月 - 2014年08月 近畿大学 農学部水産学科 教授
  • 1997年 - 1999年 海洋科学技術センター 海洋生態・環境研究部 研究員
  • 1996年 - 1997年 科学技術進行事業団 特別研究員
  • 1995年 - 1996年 日本学術振興会 特別研究員
  • 1991年 - 1993年 神奈川県水産試験場 技師

学歴

  •         - 1996年   北海道大学   水産学研究科   漁業学
  •         - 1996年   北海道大学
  •         - 1991年   北海道大学   水産学部   漁業
  •         - 1991年   北海道大学

所属学協会

  • アクアバイオメカニズム研究会   日本水産学会   日本水産工学会   

研究活動情報

論文

  • Francois Poisson, Pierre Budan, Sylvain Coudray, Eric Gilman, Takahito Kojima, Michael Musyl, Tsutomu Takagi
    FISH AND FISHERIES 2021年12月 
    For many years, tremendous effort has been dedicated to developing new industrial tuna fisheries, while their adverse impacts on threatened marine species have received relatively little attention. In tuna fisheries, bycatch is the major anthropogenic threat to marine megafauna in general, particularly sharks. Research on the development of gear technology for bycatch reduction and potential mitigation measures helped tuna Regional Fisheries Management Organizations adopt bycatch reduction management measures. After reviewing past research on the development of mitigation measures for pelagic longline and tropical purse seine fisheries based on pelagic species' behaviours, we describe promising new approaches integrating recent technological breakthroughs. New innovations include autonomous underwater vehicles carrying cameras along with miniaturized sensors, aerial drones, computer simulation of fishing gear geometry, environmental DNA assays, computer visualizations and deep learning. The successful application of such tools and methods promises to improve our understanding of factors that influence capture, escape and stress of caught species. Moreover, results emerging from recent ethological research explaining the power of social connection and learning in the "fish world" such as social learning from congeners, habituation to deterrents, and how past fishery interactions affect responses to fishing gear should be taken into account when developing technical mitigation measures.
  • S. Abe, T. Takagi, S. Torisawa, K. Abe, H. Habe, N. Iguchi, K. Takehara, S. Masuma, H. Yagi, T. Yamaguchi, S. Asaumi
    Aquacultural Engineering 93 102146 - 102146 2021年05月
  • Keisuke Doi, Tsutomu Takagi, Yasushi Mitsunaga, Shinsuke Torisawa
    PLOS ONE 16 5 2021年05月 
    Fish form schools because of many possible reasons. However, the hydrodynamic mechanism whereby the energy efficiency of fish schools is improved still remains unclear. There are limited examples of fish models based on actual swimming movements using simulation, and the movements in existing models are simple. Therefore, in this study, we analyzed the swimming behavior of Biwa salmon (Oncorhynchus sp., a salmonid fish) using image analyses and formulated its swimming motion. Moreover, computational fluid dynamics analysis was carried out using the formulated swimming motion to determine the fluid force acting on the fish body model with real fish swimming motion. The swimming efficiency of the fish model under parallel swimming was obtained from the calculated surrounding fluid force and compared for different neighboring distances. The flow field around the fish model was also examined. The swimming efficiency of two fish models swimming parallelly was improved by approximately 10% when they were separated by a distance of 0.4L, where L is the total length of the model. In addition, the flow field behind the fish body was examined under both inphase and antiphase conditions and at inter-individual distances of 0.8L and 1.2L. The apparent flow speed in the distance range of 0.5-2.0L from the midpoint of the snouts of the two individuals was lower than the swimming speed. The pressure distribution on the fish model showed an elevated pressure at the caudal fin. Interestingly, we obtained an isopleth map similar to that of a caudal peduncle. To avoid a negative thrust, the aft part of the body must be thin, as shown in the isopleth map obtained in this study.
  • Shintaro Gomi, Tsutomu Takagi, Katsuya Suzuki, Rika Shiraki, Ichiya Ogino, Shigeru Asaumi
    APPLIED OCEAN RESEARCH 106 2021年01月 
    We propose a control method that changes the geometry of a fishing net into an arbitrary geometry. To control the net geometry, an automatic control system was constructed by integrating the data assimilation method into a fishing net dynamics simulation. This study focused on the function of the data assimilation method to estimate the unknown parameter needed to control the net geometry. By applying the parameter estimation, the length of the material and loading were set as unknown parameters and estimated to be an intended geometry of the fishing net. Further, geometry control experiments consisting of numerical simulations were conducted for validation. This was achieved by using a simplified plane net model and a trawl net model. An automatic control system using the extended Kalman filter was applied. In addition, we confirmed that the net geometry can be controlled in real space by the automatic control system. For validation, the results of experiments conducted in an experimental flume tank were compared with the numerical simulation results of the plane net geometry by using the automatic control system that integrated an ensemble Kalman filter. The numerical simulation results were found to be congruent with those of the flume tank experiments, confirming the validity of the proposed control system.
  • Y. Ina, T. Takagi, S. Miyashita, M. Kurata, T. Honryo, Y. Sawada, H. Fukuda, S. Torisawa
    Aquacultural Engineering 90 102099 - 102099 2020年08月
  • Tatsuya Tanaka, Kazuyoshi Komeyama, Shinsuke Torisawa, Takeharu Yamaguchi, Shigeru Asaumi, Tsutomu Takagi
    NIPPON SUISAN GAKKAISHI 85 3 314 - 320 2019年 
    In this study, we conducted three experiments to determine the performance of a multi-stereovision technique to enhance the accuracy of fish body measurement for aquaculture management. We compared the performance of the stereo cameras using two, three, and four stereo cameras in each experiment. First, we compared the performance of camera calibration. Next, we calculated the difference between the estimated three-dimensional positions of the interpolated or extrapolated control points and the true values. Further, we confirmed the relationship between the observational error of the stereo cameras and the distance from the centroid of the analytical space to measure the interpolated or extrapolated control points. Subsequently, we estimated the fork length of the fish in an aquaculture net-cage. We investigated the relationship between the observational error of the stereo cameras and the distance from the centroid of the analytical space to measure the fish positions. The result of each experiment suggests that the multi-stereovision using four cameras has higher performance than that using two or three cameras. The accuracy of stereovision using four cameras was improved more than the conventional stereo measurement using two cameras. As the error in the depth direction is reduced by the multi-stereovision using four cameras, the multi-stereo measurement may have a wider measurement space than the conventional one.
  • ステレオビジョンによるマサバの3次元遊泳行動計測:パーティクルフィルタを用いた自動計測
    坂本 誠, 米山和良, 田丸 修, 鳥澤眞介, 高木 力
    日本水産学会誌 84 5 787 - 795 2018年07月 [査読有り][通常論文]
  • 髙木 力, 米山 和良, 阿部 悟, 鳥澤 眞介, 竹原 幸生, 山口 武治, 浅海 茂
    水産工学 = Fisheries engineering 54 3 209 - 213 日本水産工学会 2018年02月 [査読無し][通常論文]
  • Makoto Sakamoto, Kazuyoshi Komeyama, Osamu Tamaru, Shinsuke Torisawa, Tsutomu Takagi
    NIPPON SUISAN GAKKAISHI 84 5 787 - 795 2018年 
    The behavior of fish in the vicinity of fishing gear and in an aquaculture tank should be analyzed to understand their responses to materials such as nets, tank walls, and other physical objects. To monitor the 3D trajectory of target fish in recorded videos automatically and thereby reduce the workload of scientists, we used a particle filter as a state-space model, which is an image processing technique, to analyze video. The behavior of a single chub mackerel of fork length of 0.34 m was monitored using stereo vision cameras in an experimental fish tank. The fish body in the recorded video was binarized using threshold and background subtraction methods of image processing. Then, a segmented image of the fish body including color information was generated by obtaining the product of the raw image and binarized image. The segmented fish body was automatically tracked in the video recorded by the stereo camera using a particle filter. The 3D trajectory of the fish was calculated using direct linear transformation methods based on the 2D trajectories in the stereo image. The trajectory was smoothed using the Kalman filter to minimize measurement error in estimated fish position. Thus, using the proposed method based on image processing, we automatically obtained the 3D trajectory of the target fish. Although the wave effect in field observation remains an issue in applying this method to fisheries research, it can be put to immediate use in tank experiments.
  • Kazuyoshi Komeyama, Tatsuya Tanaka, Takeharu Yamaguchi, Shigeru Asaumi, Shinsuke Torisawa, Tsutomu Takagi
    Journal of Robotics and Mechatronics 30 2 231 - 237 2018年 [査読有り][通常論文]
     
    For aquaculture management, aquaculture farmers require a new, inexpensive device that can obtain the size of a fish without touching them, replacing the conventional spoon-net sampling method. Conventional sampling involves the risks of physical injury and mental stress to the fish, which may affect their growth rate and mortality. Therefore, we developed methods for monitoring the size of fish, considering red sea bream (RSB) aquaculture, using commercially available cameras. This study evaluates the sample size using the estimated mean fork length value in a cage, and its value is approximately 20 samples with a 2% error rate for a fork length of greater than 30 cm. We measured the fish fork length under water in the cage using both stereo vision and net-sampling methods simultaneously. The examination demonstrated that for RSB aquaculture, the estimated values of fork length from the two methods have no statistical difference. This result implies that our stereo vision system can be effectively applied to monitor RSB growth.
  • Development and evaluation of real-time simulation system of purse seine gear dynamics
    N. Tanada, S. Gomi, T. Takagi, K. Komeyama, S. Torisawa, K. Suzuki, R. Shiraki, Y. Nishiyama, S. Asaumi
    Contributions on the Theory of Fishing Gears and Related Marine Systems 10 43 - 52 2017年10月 [査読有り][通常論文]
  • New technique to shape a fishing ne into arbitary geometry underwater
    S. Gomi, T. Takagi, N. Tanada, K. Komeyama, K. Suzuki, R. Shiraki, Y. Nishiyama, S. Asaumi
    Contributions on the Theory of Fishing Gears and Related Marine Systems 10 1 - 12 2017年10月 [査読有り][通常論文]
  • Tsutomu Takagi, Shigeru Asaumi, Shinsuke Torisawa, Masahiko Ariji
    NIPPON SUISAN GAKKAISHI 83 1 91 - 91 2017年 [査読有り][通常論文]
  • Tsutomu Takagi
    NIPPON SUISAN GAKKAISHI 83 1 92 - 92 2017年 [査読有り][通常論文]
  • S. Abe, T. Takagi, K. Takehara, N. Kimura, T. Hiraishi, K. Komeyama, S. Torisawa, S. Asaumi
    SELECTED PAPERS FROM THE 31ST INTERNATIONAL CONGRESS ON HIGH-SPEED IMAGING AND PHOTONICS 10328 2017年 [査読有り][通常論文]
     
    Because escape from a net cage and mortality are constant problems in fish farming, health control and management of facilities are important in aquaculture. In particular, the development of an accurate fish counting system has been strongly desired for the Pacific Bluefin tuna farming industry owing to the high market value of these fish. The current fish counting method, which involves human counting, results in poor accuracy; moreover, the method is cumbersome because the aquaculture net cage is so large that fish can only be counted when they move to another net cage. Therefore, we have developed an automated fish counting system by applying particle tracking velocimetry (PTV) analysis to a shoal of swimming fish inside a net cage. In essence, we treated the swimming fish as tracer particles and estimated the number of fish by analyzing the corresponding motion vectors. The proposed fish counting system comprises two main components: image processing and motion analysis, where the image-processing component abstracts the foreground and the motion analysis component traces the individual's motion. In this study, we developed a Region Extraction and Centroid Computation (RECC) method and a Kalman filter and Chi-square (KC) test for the two main components. To evaluate the efficiency of our method, we constructed a closed system, placed an underwater video camera with a spherical curved lens at the bottom of the tank, and recorded a 360 degrees view of a swimming school of Japanese rice fish (Oryzias latipes). Our study showed that almost all fish could be abstracted by the RECC method and the motion vectors could be calculated by the KC test. The recognition rate was approximately 90% when more than 180 individuals were observed within the frame of the video camera. These results suggest that the presented method has potential application as a fish counting system for industrial aquaculture.
  • Kazuyoshi Komeyama, Minoru Kadota, Hiroyuki Sueshige, Kazuhiko Anraku, Tsutomu Takagi
    Fisheries Engineering 53 1 1 - 13 日本水産工学会 2016年07月 [査読有り][通常論文]
     
    状態空間モデルであるカルマンフィルタの適用で,大型水槽(600 m3)における超音波テレメトリーで計測した魚の3 次元位置を推定した。超音波発信機を装着した3 個体のマダイ(63,75,84 kHz)を4 つのハイドロホンによって同時追跡した。4 つのハイドロホンに到達する送信信号の時間差に基づき計算される双曲面の交点によって標識魚の位置を推定した。この3 次元超音波テレメトリーシステムの性能テストでは,最も結果の良かった63 kHz の超音波発信機で,確度が0.69 m,精度が0.02‒0.04 m で推定できた。確度,精度の結果はともに水平成分よりも鉛直成分が低く,精度に関しては超音波発信機の発振周波数の増加とともに低くなった。これらの結果は,発振周波数に対する十分なサンプリングレートに改善することで精度の向上が見込まれる可能性を示した。双曲面交点より推定された値には誤差が含まれるため,実験個体の推定位置が水槽域外に出ることもあった。そこでカルマンフィルタによる状態空間モデルで推定位置を補正した。その結果,3 個体の遊泳軌跡の水平成分は水槽域内に入った。本研究では,誤差の補正が必要なことの多い超音波テレメトリーによる位置推定に状態空間モデルを適用することで,実際の遊泳軌跡に近似させることが可能であることを示した。
  • Holger Korte, Jan-Hendrik Wesuls, Sven Stuppe, Tsutomu Takagi
    IFAC PAPERSONLINE 49 23 440 - 445 2016年 [査読有り][通常論文]
     
    The interest of computer-aided investigations of structure motions in maritime applications has become more relevant during the last years. The present work deals with the 6DOF (six degrees of freedom) motion-simulation of a free floating vessel in a seaway. A comparison between the calculation of forces and moments in the body-fixed system using the Kirchhoff-Motion-Equations and the calculation within the inertial coordinate system is shown. For this purpose, the relevant equations are defined in the inertial reference frame. Special attention applies to the matrices of mass and moment of inertia. Due to hydrodynamic effects in maritime applications and the transformation from a moving body-fixed reference frame, these matrices are time varying in the inertial reference frame. Finally, a comparison of the registered ship motions in the body-fixed and the inertial reference frame is presented. (C) 2016, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
  • Tsutomu Takagi, Shizuka Ito, Shinsuke Torisawa, Yoshinobu Inada
    Journal of Aero Aqua Bio-mechanisms 4 1 78 - 82 Society of Aero Aqua Bio-mechanisms 2015年06月 [査読有り][通常論文]
     
    A constrained swimming test showed that at fastest flow speeds, the tail-beat frequencies (TBF) of followers in a school of Japanese chub mackerels were significantly lower than those of the leading fish. The gross cost of transport (GCOT) of schooling fish was 4.8-6.6 J·kg-1·m-1, whereas that of solitary swimming fish was significantly larger (9.2-11.5 J·kg-1·m-1). To examine the association between the configuration of individuals in the school and energy-saving, the three-dimensional positions of individuals in a school were measured in a large tank. Although the school was not arranged in the diamond pattern known to be most effective for energy conservation, the TBF of the followers remarkably decreased when within the range of 1.4 BL (Body Length) from the leading fish in the school. The energy gain of schooling fish was greater than that derived from the potential-theory basis, implying a potential hydrodynamic synergy effect.
  • Yoshiaki Ina, Wataru Sakamoto, Shigeru Miyashita, Hiromu Fukuda, Shinsuke Torisawa, Tsutomu Takagi
    FISHERIES SCIENCE 80 6 1293 - 1299 2014年11月 [査読有り][通常論文]
     
    It is necessary to understand the processes involved in sinking death in Pacific bluefin tuna Thunnus orientalis aquaculture in order to develop methods to prevent or minimize this problem. We observed the nighttime vertical distribution of Pacific bluefin tuna in the water column on 2-9 DAH and the morphological characteristics of the larvae, in order to clarify the processes involved in sinking death. A cuboid tank (height 300 cm) was used to measure vertical distribution. The number of larvae was counted in each of 4 regions in the observation tank: upper layer (water depth 0-100 cm), middle layer (100-200 cm), lower layer (200-300 cm), and bottom area. The distribution of larvae in these regions at 4 days after hatching was polarized to the upper layer and bottom area. Individuals with inflated swim bladders were observed in the upper layer 3 days after hatching. No larvae with inflated swim bladders were observed in the bottom area on any day after hatching. Total body length and caudal fin aspect ratio of larvae with both inflated and un-inflated swim bladders were greater in the upper layer than those of larvae in the bottom area. Larvae with un-inflated swim bladders that failed to develop sufficiently for swimming sank to the tank bottom and died. Swim bladder development and caudal fin swimming ability are strongly related to sinking death.
  • 高木 力, 宮田 俊輔, 伏島 一平, 大島 達樹, 上原 崇敬, 鈴木 勝也, 野村 芳徳, 金築 正道, 鳥澤 眞介
    水産工学 51 1 11 - 19 日本水産工学会 2014年07月 [査読有り][通常論文]
     
    大型まき網の操業時の水中形状を数値計算によってシミュレーションし,漁具形状の動的特性を評価した。身網の区画を上層,中層,下層の三区画に分割し,各区画の目合をオリジナルとその2倍および半分に変化させ,網地の沈下特性を比較した。網糸直径を一定にして目合を変化させた場合は,下層の網地の目合の違いが最も沈降速度と深度に影響を与えた。網糸の太さを変えずに,下層の網地の目合を大きくすることによって沈降速度が増加することになり,操業の効率化が期待できる。
  • Hiromu Fukuda, Shinsuke Torisawa, Tsutomu Takagi
    BULLETIN OF FISHERIES RESEARCH AGENCY 38 135 - 139 2014年03月 [査読有り][通常論文]
     
    Behavioral traits under light and dark conditions were evaluated in larval and juvenile stage Pacific bluefin tuna (PBF), Thunnus orientalis. Light/dark conditions affected behavior of PBF throughout the growth stages examined in the present study (from 20 to 55 days post hatching). PBF displayed schooling behavior under light conditions from 27 days post hatching, while they did not display well-coordinated schooling behavior under dark conditions at any point during the present study. Under dark conditions, PBF swam slower than they did under light conditions. From 20 to 29 days post hatching, PBF demonstrated particularly slower swimming behaviors under dark conditions. Results of the present study suggested that both larval and juvenile PBF swam actively under light conditions, and that they formed coordinated schools from 27 days post hatching when exposed to an environment with sufficient visibility.
  • 網漁具の形状・荷重シミュレータNaLA-Systemについて
    鈴木 勝也, 髙木 力
    ていち 125 10 - 19 2014年02月 [査読無し][通常論文]
  • Tsutomu Takagi, Yumiko Tamura, Daniel Weihs
    Journal of Theoretical Biology 336 158 - 172 2013年11月07日 [査読有り][通常論文]
     
    Weihs theoretically revealed that during the movement of fish with negative buoyancy, more kinetic energy is saved in the glide and upward (GAU) swimming mode than in the continuous horizontal swimming mode. Because kinetic energy saving depends on dynamic parameters such as the drag and lift of the body, the effects of variations in these parameters on energy saving for different species remain unknown. Here, the kinetic energy saving of Pacific bluefin tuna (PBT), Thunnus orientalis, exhibiting the GAU swimming mode was investigated. The dynamic properties of PBT were estimated by carrying out CFD analysis. The CFD model was produced by using a three-dimensional laser surface profiler, and the model was controlled such that it exhibited swimming motion similar to that of a live PBT swimming in a flume tank. The drag generated by tail beating, which significantly affects the kinetic energy during motion, was twice that generated in the glide mode. The faster the upward swimming speed, the lesser is the kinetic energy saving therefore, when the upward swimming speed is more than twice the glide speed, there is no gain in the GAU mode. However, when SMR (Standard Metabolic Rate) is considered, if the energy based on SMR is assumed to be 30% of the total energy spent during motion, the most efficient upward swimming speed is 1.4 times the glide speed. The GAU swimming mode of PBT leads to energy saving during motion, and the upward swimming speed and the lift force produced by the pectoral fins for the most efficient drive are unique for different species of different sizes. © 2013 Elsevier Ltd.
  • Potential of computer simulation for buoy-line type of purse seine fishing
    T TAKAGI, S MIYATA, I FUSEJIMA, T OSHIMA, T UEHARA, K SUZUKI, Y NOMURA, M Kanechiku, S TORISAWA
    Contributions on the Theory of Fishing Gears and Related Marine Systems 8 55 - 62 2013年10月 [査読有り][通常論文]
  • Tsutomu Takagi
    NIPPON SUISAN GAKKAISHI 79 5 778 - 781 2013年09月 [査読有り][通常論文]
  • Kazuyoshi Komeyama, Minoru Kadota, Shinsuke Torisawa, Tsutomu Takagi
    Aquaculture Environment Interactions 4 1 81 - 90 2013年06月 [査読有り][通常論文]
     
    Swimming trajectories of aquatic animals that are estimated using the dead-reckoning technique below the sea surface tend to have very large associated observational errors. Therefore, the aim of the present study was to develop a technique for removing accumulated errors from such trajectories for Pacific bluefin tuna Thunnus orientalis. Horizontal and vertical speeds and heading angle were measured in an aquaculture net cage using 2 types of data loggers, and current velocity was recorded at a depth of 12 m to measure the tidal current speed around the net cage. Fourier analysis indicated that the primary source of error in trajectory estimates was the effect of ocean currents, which resulted in drift, and further analysis revealed that the frequency contributing to drift was consistent with the low-frequency signal in a spectrum analysis of horizontal speed. Therefore, a high-pass filter was applied to horizontal speed data to remove any frequencies lower than the cut-off frequency (0.0015 Hz), following which these data were back-transformed into a time domain that no longer included the drift effect caused by the current. The reconstructed trajectories fit within the inner diameters of the net cage, indicating that they were realistic. To confirm the validity of the resultant swimming trajectories, a flume tank experiment was conducted, which demonstrated that the high-pass filter effectively removed current drift from the estimated trajectory. Furthermore, since the method was estimated to have a precision of approximately 0.20 m, it not only allows the 3-dimensional trajectories of circling tuna to be estimated but can also be applied to the behavior of fish in the wild.
  • Energy Saving Effect of Fish Schooling in the Japanese Mackerel, Scomber joponicus.
    Tsutomu Takagi, Shizuka Ito, Shinsuke Torisawa, Yoshinobu Inada
    Mathmatical and Physical Fisheries Science 10 2 - 13 2013年05月 [査読有り][通常論文]
  • Tsutomu Takagi
    Nippon Suisan Gakkaishi (Japanese Edition) 78 5 1018  2012年 [査読有り][通常論文]
  • Minoru Kadota, Shinsuke Torisawa, Takeshi Yamane, Tsutomu Takagi
    Fisheries Engineering 48 3 197 - 203 日本水産工学会 2012年 [査読有り][通常論文]
     
    海面魚類養殖業に使用される餌量は大部分が,海面漁業により生産されたもので構成されている。そのため,当該養殖生産量は海面漁業生産量とそこから養殖生産用餌量に転換される割合に強く支配されることが予想できる。本論文は,海面漁業生産量が海面養殖生産量に与える影響をシンプルな数理モデルを導入することによって評価する方法を提案するものである。海面食料生産量の増減をできるだけ簡易に評価する方法を提示し,得られた結果から,現況の海面養殖生産量の限界が評価できる可能性を示した。
  • Shinsuke Torisawa, Minoru Kadota, Kazuyoshi Komeyama, Tsutomu Takagi
    Fisheries Engineering 49 1 13 - 20 日本水産工学会 2012年 [査読有り][通常論文]
     
    デジタルステレオカメラを用いて,生簀内を自由遊泳する養成クロマグロの3次元計測を実施した。生簀内の養成個体の尾叉長と体長組成の推定は,DLT法を用いることで行った。養成魚管理を行ううえで必要とされるこれらの情報をステレオ撮影画像から取得することができた。本研究では,これまでは特殊な方法となっていたステレオ画像解析を,DLT法を用いた簡便な養殖時の養成魚モニタリング手法として構築することを試みた。さらに,同一個体の繰り返し計測から,推定値の妥当性を評価した結果,ステレオカメラシステムからの距離が9.2m以内で撮影された対象魚は,誤差率が養殖業者に望まれる値となる5%以内で,尾叉長を推定できることが確認できた。これらの結果から,今回提案する簡便なステレオ解析手法は,養成魚に負荷を与えることなく,養成魚管理に非常に役立つ情報を提供できることが明らかとなった。
  • Minoru Kadota, Eric J. White, Shinsuke Torisawa, Kazuyoshi Komeyama, Tsutomu Takagi
    PLoS ONE 6 12 e28241  2011年12月02日 [査読有り][通常論文]
     
    In order to make quantitative statements regarding behavior patterns in animals, it is important to establish whether new observations are statistically consistent with the animal's equilibrium behavior. For example, traumatic stress from the presence of a telemetry transmitter may modify the baseline behavior of an animal, which in turn can lead to a bias in results. From the perspective of information theory such a bias can be interpreted as the amount of information gained from a new measurement, relative to an existing equilibrium distribution. One important concept in information theory is the relative entropy, from which we develop a framework for quantifying time-dependent differences between new observations and equilibrium. We demonstrate the utility of the relative entropy by analyzing observed speed distributions of Pacific bluefin tuna, recorded within a 48-hour time span after capture and release. When the observed and equilibrium distributions are Gaussian, we show that the tuna's behavior is modified by traumatic stress, and that the resulting modification is dominated by the difference in central tendencies of the two distributions. Within a 95% confidence level, we find that the tuna's behavior is significantly altered for approximately 5 hours after release. Our analysis reveals a periodic fluctuation in speed corresponding to the moment just before sunrise on each day, a phenomenon related to the tuna's daily diving pattern that occurs in response to changes in ambient light. © 2011 Kadota et al.
  • Minoru Kadota, Shinsuke Torisawa, Tsutomu Takagi, Kazuyoshi Komeyama
    Fisheries Science 77 6 993 - 998 2011年11月 [査読有り][通常論文]
     
    We explore how a stochastic model provides the most promising avenue towards predicting fish movement. To construct a stochastic model describing fish movement, trajectories of ten juveniles in a water tank were analyzed from a stochastic point of view. The heading angle was defined as a random variable. Our analysis found that the most probable forward heading angle was between 0° and 22.5° (probability ~78%), followed by angles between 22.5° and 45° (probability ~10%). We also found that the choice of future heading angle depends on the current heading angle. Therefore, we treated heading angle state as a first-order Markov process and constructed a correlated random walk model describing juvenile movement in a water tank. Our stochastic model simulated a trajectory similar to observed trajectories. We used the model as a tool for estimating the probability distribution of potential fish path outcomes. We derived the distribution of potential outcomes from a large number of simulations (N = 1000) and investigated these trajectories. We collected a set of juvenile trajectories that collided with the tank and estimated the probability of juvenile collisions with the tank. © 2011 The Japanese Society of Fisheries Science.
  • S. Torisawa, H. Fukuda, K. Suzuki, T. Takagi
    Journal of Fish Biology 79 5 1291 - 1303 2011年11月 [査読有り][通常論文]
     
    The effects of vision development and light intensity on schooling behaviour during growth in juvenile Pacific bluefin tuna Thunnus orientalis were investigated using both behavioural and histological approaches. The schooling behaviour of three age groups [25, 40 and 55 days post hatching (dph)] of juvenile T. orinetalis were examined under various light intensities. Subsequently, schooling variables, such as the nearest neighbour distance (D NN) and the separation swimming index (I SS), were also measured under different light intensities. Furthermore, retinal indices of light adaptation in juvenile fish at each experimental light intensity and visual acuities in six stages (25-55 dph) of juveniles were examined histologically. During growth, the light intensity thresholds of I SS decreased from 5 to 0·05 lx, and D NN under light conditions (> 300 lx) also decreased from 9·2 times the standard length (L S) to 1·2 times L S. The thresholds of light intensities for the light adaptation of retinas in juveniles (25-55 dph) similarly decreased from 5 to 0·05 lx with growth. In addition, the visual acuities of juveniles developed from 0·04 to 0·17 with decreasing D NN. These data clearly indicate that the characteristics of schooling behaviour strongly correspond to the degree of vision development. Juvenile T. orinetalis also appear to be more dependent on cone rather than rod cells under low light intensity conditions, resulting in a relatively high light intensity threshold for schooling. These results suggest that juveniles can adapt to darker conditions during growth by developing improved visual capabilities. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.
  • Yoshio Kunimune, Yasushi Mitsunaga, Kazuyoshi Komeyama, Masanari Matsuda, Toru Kobayashi, Tsutomu Takagi, Takeshi Yamane
    Fisheries Science 77 4 521 - 532 2011年07月 [査読有り][通常論文]
     
    Seasonal habitat use by nigorobuna Carassius auratus grandoculis Temminck et Schlegel and gengoroubuna Carassius cuvieri (Temminck et Schlegel) in Lake Biwa was investigated using acoustic telemetry. Twenty- three nigorobuna and 11 gengoroubuna specimens caught using set-nets in the lake's south basin were surgically fitted with acoustic transmitters and then released. Signals from the fishes were recorded by 23 receivers installed around the lake. Between April and June 2007, the first spawning season after release, signals were received from all tagged fishes. Thereafter, until the second spawning season, signals were collected from 26 and 45% of released nigorobuna and gengoroubuna individuals, respectively. Seasonal habitat preferences for these species were studied by distance-based analysis. The analysis revealed that nigorobuna tended to stay near their spawning area in the south basin of the lake throughout the year, whilst gengoroubuna tended to show a seasonal migration pattern between the north and south basins. After the spawning season, the latter species migrated to the north basin where it remained until the next spawning season, when it returned to the south basin. This is the first report of seasonal migration of nigorobuna and gengoroubuna in Lake Biwa. © 2011 The Japanese Society of Fisheries Science.
  • Hiromu Fukuda, Yoshifumi Sawada, Tsutomu Takagi
    AQUATIC LIVING RESOURCES 24 2 113 - 119 2011年04月 [査読有り][通常論文]
     
    To reveal the kinematical aspects of schooling development in the Pacific bluefin tuna Thunnus orientalis, changes in its schooling behaviour traits, local behaviour transmission among school members and morphological traits were investigated as fish developed from the larval to the juvenile stage. Schooling was first observed at around 24 days post-hatching (27 mm body length) in T. orientalis. Behaviour transmission among individuals took much longer among 24 d post-hatching individuals than among older fish. The compactness and polarity of the school progressively improved as the time required for behaviour transmission decreased. One cause of the reduction in the time required for behaviour transmission was the development of manoeuvrability, which resulted from further morphological development of the caudal fin and other organs related to swimming.
  • Shinsuke Torisawa, Minoru Kadota, Kazuyoshi Komeyama, Katsuya Suzuki, Tsutomu Takagi
    Aquatic Living Resources 24 2 107 - 112 2011年04月 [査読有り][通常論文]
     
    We used a digital stereo-video camera system for three-dimensional monitoring of cultured Pacific bluefin tuna, Thunnus orientalis, swimming freely in a net cage. We estimated the fork length and length frequency distribution of individual fish using the direct linear transformation (DLT) method. Information obtained from stereo images is useful for managing the growth of tuna during rearing. Our aim was to develop a simple method involving a combination of DLT and commercial image-processing software to enable aquaculturists to obtain three-dimensional measurements of fish. In this study, we used a stereo-video camera system to evaluate the precision and validity of fish size estimates determined from repeated measurements. Of the total assessed individuals swimming within a distance of < 5.5 m from the camera system, estimates for 99% (106/107) were found to be valid, with an error ratio (standard error/mean) of < 5%. Therefore, we believe that our proposed simple method for monitoring free-swimming fish could be very useful for aquaculture management. © EDP Sciences, IFREMER, IRD 2011.
  • Kazuyoshi Komeyama, Minoru Kadota, Shinsuke Torisawa, Katsuya Suzuki, Yuichi Tsuda, Tsutomu Takagi
    Aquatic Living Resources 24 2 99 - 105 2011年04月 [査読有り][通常論文]
     
    The swimming path of a reared Pacific bluefin tuna, Thunnus orientalis, was measured in a submerged aquaculture net cage to understand how reared fish use the space in such a cage. A bluefin tuna (fork length, FL, 0.51 m) was captured by angling in the cage, and two micro data loggers (PD3GT, Little Leonardo DST Comp-Tilt, Star-Oddi) were attached to its body. The fish was then released back into the net cage. The PD3GT measured its swimming speed and depth at 1-s intervals and recorded these in flash memory. The DST Comp-Tilt measured the magnetic field strength at 1-s intervals and recorded the heading estimated from the magnetic field strength in flash memory. The fish moved through the water in the cage at speeds of 0.7-0.8 m s -1 and attained a maximum speed of 3.6 m s -1. Burst swims exceeding 2 m s -1 were confirmed only after dark and a significant difference was found between the daytime and night-time swimming speeds (p < 0.001). The fish moved at depths between 2 and 22 m, swimming near the bottom during the day and at 10-15 m at night, with a significant difference in swimming depth between day and night (p < 0.001). The swimming path reconstructed by dead reckoning was visualised using night-time data. For this period, the absolute speed was corrected from 0.75 ± 0.09 m s -1 to 0.71 ± 0.15 m s -1 by removing the accumulated error from the reconstruction vector. This study allowed us to examine the behaviour of a tagged tuna in three dimensions and is the first to monitor the behaviour of a bluefin tuna in a submerged net cage. Although only one fish was analysed, this study provides useful information on the space use of reared fish in aquaculture net cages. Future studies must obtain sufficient data to understand the underlying generalities of tuna behaviour. © EDP Sciences, IFREMER, IRD 2011.
  • Hiromu Fukuda, Shinsuke Torisawa, Takeshi Yamane, Tsutomu Takagi
    Fisheries Engineering 48 2 117 - 124 日本水産工学会 2011年 [査読有り][通常論文]
     
    湖産アユの群行動と走流性の特徴を精査した。400lxの照度環境下で,アユは個体間距離が短く極性の低い群れを形成したが,低照度環境下(0.01lx)では,群れを形成しなかった。また,3.3cm s^<-1>以上の流速に対して,アユは正の走流性を示し,特に5.2cm s^<-1>以上の流速では水槽底面に対して魚体を定位させる頻度が高まった。しかし3.3cm s^<-1>未満の流速に対しては,アユは顕著な反応行動を示さなかった。この結果は,比較的弱い流れが本種の走流性の誘因にならないことを示している。これらの結果から,流動環境が本種の遊泳方向や移動距離に影響を与える因子であることが示された。また,比較的に極性が低い魚群を形成する湖産アユのような種では,流動環境が行動や移動に与える影響は特に強くなることが示唆された。
  • Hiromu Fukuda, Shinsuke Torisawa, Yoshifumi Sawada, Tsutomu Takagi
    AQUACULTURE 305 1-4 73 - 78 2010年07月 [査読有り][通常論文]
     
    Schooling behavior traits during the process of retinomotor response from scotopic to photopic vision were examined in cultivated juvenile Pacific bluefin tuna (PBT) at 3 different ages. After a sudden change in illumination from darkness to 300 lx, retinal adaptations changed from scotopic to photopic vision. Retinomotor and schooling indices showed strong agreement, with juvenile PBTs forming polarized schools upon complete retinal adaptation to photopic vision. The behavioral and retinal adaptation to sudden illumination took 20, 15, and 10 min after illumination in PBT 25, 40, and 55 days after hatching (dah). At 40 dah, PBT took a longer time to adapt than fish aged 55 dab and showed the highest swimming speed, including momentary bursts of swimming immediately after illumination. This suggested that these fish were swimming at high speed under poor visibility conditions. In contrast, PBT at 55 dah showed a gradual increase in swimming speed that correlated with their retinal adaptation. Therefore, behavioral and retinal adaptation traits changed during growth, suggesting that the high mortality in PBT around 40 dah, due to collisions with the tank and net walls at dawn, may be because these adapt more slowly than fish at 55 dah and were swimming at a relatively high speed under conditions of poor visibility. (C) 2010 Elsevier B.V. All rights reserved.
  • H. Fukuda, S. Torisawa, Y. Sawada, T. Takagi
    JOURNAL OF FISH BIOLOGY 76 7 1841 - 1847 2010年05月 [査読有り][通常論文]
     
    Schooling was first observed at 25-27 days after hatching (26.2-33.8 mm, total length) in the Pacific bluefin tuna Thunnus orientalis. At this time, the mode of swimming changed from intermittent sprinting to continuous cruising, and this allowed the fish to adjust to an inertial hydrodynamic environment. (C) 2010 The Authors Journal compilation (C) 2010 The Fisheries Society of the British Isles
  • Tsutomu Takagi, Ryo Kawabe, Hiroyuki Yoshino, Yasuhiko Naito
    AQUATIC BIOLOGY 9 2 149 - 153 2010年 [査読有り][通常論文]
     
    Although technologies such as archival tags have been developed to monitor the behaviour of free-swimming fish, more advanced techniques are required in order to understand the basis of their behaviour. To assess the glide behaviour of the negatively buoyant Japanese flounder Paralichthys olivaceus, we adopted a new approach to examine the importance of the physical aspects of its swimming performance by integrating in situ bio-logging data from free-swimming fish with corresponding computational fluid dynamics (CFD) analyses. Field data from the data loggers revealed that flounder commenced powerless glides after swimming upwards. A theoretical simulation of this glide using CFD analysis revealed that the body angle producing the maximum lift/drag ratio was in agreement with the field data and that, during a glide, the moment equilibrium body angle of the flounder resulted in the longest glide distance. This suggests that the morphology of the flounder confers stability on its glide, making this mode of movement more energetically efficient.
  • Yumiko Tamura, Tsutomu Takagi
    FISHERIES SCIENCE 75 3 567 - 575 2009年05月 [査読有り][通常論文]
     
    Morphological features of Pacific bluefin tuna Thunnus orientalis have important functions for its fast swimming. Morphological features of tuna change with growth; therefore, morphological functions may develop during this process. In this study, we precisely quantified the morphology of bluefin tuna with growth from juvenile to young adult using a three-dimensional laser profiler and evaluated the fluid dynamic characteristics of tuna using computational fluid dynamics (CFD) and an accurate model based on measured data. As results of measurement of morphological features, the aspect ratio and sweepback angle, which are indices of hydrodynamic characteristics for a hydrofoil, suggested that the lift force of caudal fin was increased as the tuna grows. The results of CFD analysis showed that the coefficient of drag force gradually decreased with growth. Pectoral fins generated lift force, and the ratio of lift force to submerged weight (FL/SW) increased as the tuna grew to 0.2 m total length (TL). After the tuna exceeded 0.2 m TL, FL/SW changed to a wider range in angle of attack as the tuna grew. These results suggest that the morphological function of bluefin tuna develops to enhance its swimming ability as it grows from juvenile to young adult.
  • 音響標識個体の出現と定置網の漁獲量に影響を与える環境要因の評価―2個体分散遺伝的アルゴリズムを用いた解析
    髙木 力, 山根 猛, 光永 靖, 鈴木勝也, 米山和良, 松田征也
    日本水産学会講演要旨集 166  日本水産学会大会春季大会 2009年03月 [査読無し][通常論文]
  • 幼魚期の成長に伴うクロマグロ魚群の個体間相互作用の変化
    髙木 力, 石橋 泰典, 福田漠生, 倉田道雄, 澤田
    日本水産学会講演要旨集 166  2009年03月 [査読無し][通常論文]
  • 遊泳するクロマグロ幼魚の推進力と抗力の推定
    髙木 力, 田村優美子
    日本水産学会講演要旨集 166  2009年03月 [査読無し][通常論文]
  • 超音波テレメトリーによる琵琶湖におけるニゴロブナ、ゲンゴロウブナの空間分布の季節推移
    髙木 力, 山根 猛, 光永 靖, 國宗義雄, 米山和良, 松田征也
    日本水産学会講演要旨集 51  2009年03月 [査読無し][通常論文]
  • クロマグロ沖合養殖施設の研究開発-Ⅲ NaLAを用いた波浪・流動環境における生簀網形状の数値解析
    髙木 力, 鈴木勝也, 鳥澤眞介
    日本水産学会講演要旨集 13  日本水産学会大会春季大会 2009年03月 [査読無し][通常論文]
  • クロマグロ沖合養殖施設の研究開発-Ⅱ 実海域における大型養殖施設の動態計測
    髙木 力, 鳥澤眞介, 鈴木勝也, 鉛 進, 沼口隆之, 小林次彦
    日本水産学会講演要旨集 13  2009年03月 [査読無し][通常論文]
  • クロマグロ沖合養殖施設の研究開発-Ⅰ 最適な設計技術の構築を目指して
    髙木 力, 鈴木勝也, 鳥澤眞介, 鉛 進, 沼田隆之, 小林次彦
    日本水産学会講演要旨集 13  日本水産学会大会春季大会 2009年03月 [査読無し][通常論文]
  • Morphological features and functions of bluefin tuna change with growth
    髙木 力, 田村優美子
    Fisheries Science 42 275 - 295 2009年 [査読有り][通常論文]
     
    クロマグロの形態の力学的機能性について研究した
  • Ryo Kawabe, Nagayasu Yoshiura, Katsuaki Nashimoto, Yuichi Tsuda, Takahito Kojima, Tsutomu Takagi, Tohya Yasuda, Akiko Kato, Katsufumi Sato, Yasuhiko Naito
    MARINE AND FRESHWATER BEHAVIOUR AND PHYSIOLOGY 42 4 275 - 295 2009年 [査読有り][通常論文]
     
    Analysis of high-frequency depth-recording data of adult Japanese flounder Paralichthys olivaceus (Temminck & Schlegel) with depth/temperature logging tags, released in the Tsugaru Strait of northern Japan, has yielded new insights into behavioural differences on vertical movement. Here, we document diel differences in fine-temporal-scale swimming behaviour observed from six flounder released during the no-spawning season. While the flounder remained on the seabed for the majority of the recording period, fish occasionally left the seabed, swam into the water column and then swam back to the seabed. The mean swimming duration per tagged fish ranged from 44 +/- 49 to 94 +/- 164 s, with a maximum observed swimming duration of 44.5 min. Vertical movements included one or more clear ascent and descent phases highlighted by a distinct peak. Our results reveal that in the no-spawning season nocturnal swimming is more active and frequent than during the day. Our results provide important information about diel differences in swimming behaviour with respect to vertical movement and also show the vulnerability of Japanese flounder to capture by bottom-fishing gear (e. g. trawling) during the day.
  • K. KOMEYAMA, Katsuya SUZUKI, T. TORISAWA, T. TAKAGI
    Mathematical and Physical Fisheries Science 7 97 - 104 数理水産科学会 2009年 [査読無し][通常論文]
  • Katsuya Suzuki, Shinsuke Torisawa, Tsutomu Takagi
    Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE 4 1513 - 1520 2009年 [査読有り][通常論文]
     
    Large offshore net cages have been rather successful in reducing coastal contamination and developing aquacultural technology for raising large body-size species such as bluefin tuna. Deformation and shrinkage of net cages due to severe current and waves is one of the main causes of mortality of cultivated fish, and is thus of great concern for marine cage aquaculture. Even mough the cage depth can be determined by pressure sensors at several locations on the cage, this is generally insufficient to measure the deformation and shrinkage. In this study, the dynamic shape and volume of a net cage under the influence of current and waves was analyzed using a numerical net geometry simulator previously validated by tank tests. The dynamic behavior of finite mass points distributed on the net cage under various wave and current conditions was simulated in detail, and reduction coefficients of the volume were calculated by the positions of these mass points on the cage. A drastic reduction of the cage volume occurred for a current velocity of 0.28-0.39 m/s. As the current velocity increased, the deepest point of the cage changed position, moving toward the downstream direction. The effective reduction of cage volume for a wave height of 3 m and a current velocity of 0.26 m/s was the same as that for a wave height of 5 m without any current. These results suggest that the volume deformation must be based on the actual measured depth of each part of the net cage, that the combination of wave levels and current velocities may have synergistic effects on the reduction of cage volume, and that our computational method is valid for estimating the volume reduction of a net cage under the influence of a concurrent wave and current field. Copyright © 2009 by ASME.
  • K. Komeyama, K. Suzuki, T. Takagi, Y. Mitsunaga, T. Yamane, T. Hiraishi
    FISHERIES MANAGEMENT AND ECOLOGY 15 5-6 347 - 355 2008年10月 [査読有り][通常論文]
     
    The occurrence of common carp, Cyprinus carpio L., and the environmental conditions near a set-net were monitored using acoustic telemetry and a data logger to elucidate the conditions under which carp approached the net. The occurrence of one-tagged fish was analysed using a genetic algorithm (GA); GAs are based on genetic mechanisms and use the natural selection of genotypes to model various explanatory variables to provide a solution. The conditions near the set-net were simulated, including the current profile, wind system, water temperature and rainfall, and the pattern of factors that influenced the occurrence of the tagged fish were assessed using the GA. The occurrence of the tagged carp was related to lower water temperatures. The GA approach selected a significant portion of the truly important factors. Many factors can influence fish behaviour and GAs are an effective method for the analysis of complex biological phenomena.
  • クロマグロ幼魚の推進エネルギーと移動コスト視覚特性が群行動に与える影響
    髙木 力, 石橋 泰典, 山根 猛, 福田漠生, 鈴木勝也, 山根猛, 澤田好史, 岡
    日本水産学会講演要旨集 173  日本水産学会大会春季大会 2008年03月 [査読無し][通常論文]
  • Numerical analysis of dynamic behavior of Danish seining and sea trial verification,
    髙木 力, Suzuki Katsuya
    Mathematical and Physical Fisheries Science 6 11 - 22 2008年 [査読無し][通常論文]
  • GAを用いた琵琶湖におけるコイの集散に関わる環境要因の評価
    米山 和良, 鈴木 勝也, 髙木 力, 光永 靖, 山根 猛, 平石 智徳
    数理水産科学 5 16 - 26 2008年 [査読無し][通常論文]
  • Katsuya Suzuki, Tsutomu Takagi
    Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE 3 865 - 870 2008年 [査読有り][通常論文]
     
    Boat seine fishing is used to catch mainly demersal species it has many benefits such as reduced energy and labor costs, and low damage to the sea bottom if it is controlled. This fishing technique has complex motion between the seine boat and the supple net over large operating areas therefore, the dynamics of its operating processes during fishing are unknown. To investigate the dynamics of boat seine fishing in detail, we calculated its dynamics during a fishing operation using a net geometry simulation system that we developed. Two experimental surveys were carried out in January 2007 at Hokkaido, Japan. Latitude, longitude, and depth were measured in 10 places, from casting the anchor buoy to picking up the seine net. Depth sensors were installed at the top and bottom of the seine net mouth to record a time series of net shape during fishing. Using our net geometry simulator, we simulated net shape and the dynamics of boat seine fishing based on ship position and net depth. Very close agreement was observed between the experimental and simulated depths of the top and bottom of the net mouth during fishing. Three-dimensional visualization of the simulation results showed the capture processes of this fishing technique in a large scale operation. This study shows that our method is valid for modeling fishing operations to better implement smart fishing. Copyright © 2008 by ASME.
  • Tsutomu Takagi, Takashi Shimizu, Holger Korte
    ICES JOURNAL OF MARINE SCIENCE 64 8 1517 - 1524 2007年11月 [査読有り][通常論文]
     
    We developed a net shape and load analysis system (NaLA) that can estimate the three-dimensional shape of fishing gear underwater computationally. This paper introduces the latest version of the numerical model of the NaLA. Previously, NaLA was used to estimate the net geometries and internal forces of some fishing gear, demonstrating its general versatility. However, the ultimate goal of our study has been to learn about the impact of fishing and the capture process from a physical perspective, not simply to develop elemental technologies for gear design. Accurate, quantitative evaluation of fishing gear performance from a physical perspective can be used to estimate the potentialities of the ghost fishing to gillnet gears. Although the applications are not limited to geometries and internal forces, the paper describes how computer-aided simulations of fishing gear should be applied to investigations of the impact of ghost fishing caused by lost drift and bottom gillnets. The computational results showed that a driftnet with homogenous net panels was deformed slightly and bent only at the two ends of the net. Accumulation of periphyton on a bottom gillnet after 25 d of immersion caused it to settle to the sea bottom.
  • Evaluating developmental changes in schooling behavior in cultivated Pacific bluefin tuna Thunnus orientalis using a mathematical model
    H FUKUDA, S TORISAWA, K SUZUKI, Y ISHIBASHI, M KURATA, Y SAWADA, T TAKAGI, T YAMANE
    Contributions on the Theory of Fishing Gears and Related Marine Systems 5 297 - 305 2007年11月 [査読有り][通常論文]
  • Shinsuke Torisawa, Tsutomu Takagi, Yasunori Ishibashi, Yoshifumi Sawada, Takeshi Yamane
    FISHERIES SCIENCE 73 5 1202 - 1204 2007年10月 [査読有り][通常論文]
  • S. Torisawa, T. Takagi, H. Fukuda, Y. Ishibashi, Y. Sawada, T. Okada, S. Miyashit, K. Suzuki, T. Yamane
    JOURNAL OF FISH BIOLOGY 71 2 411 - 420 2007年08月 [査読有り][通常論文]
     
    Schooling behaviour and histological retinal light adaptation in juvenile Pacific bluefin tuna Thunnus orientalis were examined under various light intensities to determine the effect of light intensity on behaviour. After monitoring the schooling behaviour of juveniles 35-36 and 45-46 days post hatching, schooling variables such as nearest neighbour distance and separation swimming index were measured under different light intensities. Furthermore, retinal indices of light adaptation were investigated histologically for each experimental light intensity. Under intensities >5 lx, schooling variables in the two juvenile growth stages were nearly constant, allowing schooling. In contrast, the schooling variables indicated that the fish gradually swam more widely and randomly with decreasing light intensities <5 lx. The retinal indices also showed a shift from light adaptation to dark adaptation at light levels <5 lx. From 5 to 0-01 lx, retinal adaptation and fish schooling behaviour changed with light intensity. These data suggest that the schooling behaviour of juvenile Pacific bluefin tuna is greatly affected by retinal adaptation. (c) 2007 The Authors Journal compilation (c) 2007 The Fisheries Society of the British Isles.
  • Takashi Shimizu, Tsutomu Takagi, Holger Korte, Tomonori Hiraishi, Katsutaro Yamamoto
    FISHERIES SCIENCE 73 3 489 - 499 2007年06月 [査読有り][通常論文]
     
    The net-shape and loading analysis system (NaLA) was developed to determine fishing net configuration and load in a previous study. The system has since been applied to general gill nets and aquaculture nets, and its validity has been proven through model experiments in tanks. In this study, the system was applied to estimate the dynamic behavior of a bottom gill net for walleye pollock, to test the system's applicability of the system to gear operations in the field. To obtain in situ data, four bottom gill net operations were performed in February 2004 off the coast of Sawara, Hokkaido, Japan. During operations, vertical displacements of the bottom gill net's float and sinker lines were measured as representative values of gear behavior, and ocean current direction, and speed at the gear position were observed simultaneously. Then, bottom gill net behavior was simulated using NaLA, incorporating observed environmental conditions and gear specifications. The resulting calculated behavior was compared to measured behavior in terms of the relationship between net height and environmental or setting conditions. Agreement between the calculated and measured net behavior was found. Thus, it is believe that our NaLA calculation model has the potential to simulate the dynamic behavior of bottom gill nets in situ.
  • Tsutomu Takagi, Takashi Shimizu, Holger Korte, Katsuya Suzuki
    Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE 5 45 - 52 2007年 [査読有り][通常論文]
     
    As fishing gear consists mainly of netting and rope, and lacks a definite geometry of its own, external forces acting on the netting and other rigging determine its geometry. The underwater geometries and loads of most fishing gear cannot be grasped in detail. However, the versatile simulation technique that we have developed for fishing gear allows us to understand the physical properties of dynamic fishing gear underwater. This will allow companies to design optimal fishing gear, based on scientific research and avoiding empirical procedures. In addition, it will allow fishermen to evaluate and improve their standard operating techniques, and to develop optimal techniques. The calculation model assumes that the net consists of lumped point masses that are interconnected by mass-less springs. The equations of motion of these point masses can be expressed in a local coordinate system, which simplifies the treatment of the hydrodynamic forces acting on each mass using the inertia transformation algorithm. The computer simulation not only estimates the overall shape of fishing gear but also its mesh geometry, the tension on the netting, and the impact force on the sea bed. This will allow the development of smart gear and smart fishing. Users will be able to develop and operate fishing and aquaculture gear based on a sound understanding of the physical parameters, and design gear that is economical, efficient to operate, and less harmful to the ecosystem. In this paper, we introduce the net geometry simulation system (NaLA) and discuss how to apply the system to developing smart gear and smart fishing. Copyright © 2007 by ASME.
  • Katsuya Suzuki, Shinsuke Torisawa, Tsutomu Takagi
    Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE 5 69 - 75 2007年 [査読有り][通常論文]
     
    Population density and space limitation have proven important considerations for both fisheries management and aquaculture, resulting in intense interest in the development of new techniques and technologies for management and hatchery applications. To investigate the effects of space limitation and population density on the schooling behavior of fish, we examined the schooling behavior of captive juvenile chub mackerel. Three groups of fish were collected collections were made at 18, 42, and 73 days post-hatch (dph) at which mean body lengths were 2.28, 8.83, and 11.4 cm, respectively. The two-dimensional movement of individuals during 200-s observation periods was digitized and processed. A mathematical model based on Newton's second law of motion was used to quantify the forces dominating schooling behavior. The forces of swimming motion were quantified for each fish in a school as the propulsive force due to the swimming ability of each fish, the interactive force used to keep the proper distance and maintain similar velocity with neighboring fish, and the repulsive force used to keep a proper distance from the wall. The magnitude of the repulsive force was minimized in the 18-dph school, maximized in the 42-dph school, and decreased in the 73-dph school. The magnitudes of the propulsive and interactive forces increased with growth. Thus, the interactive force, which was critical for school formation and maintenance appears to reduce the importance of the repulsive force and causes the decline in the repulsive force between 18 and 73 dph. Copyright © 2007 by ASME.
  • Quantitative analysis of schooling behaviour and retinomotor response in juvenile Pacific bluefin tuna under different light intensities
    髙木 力, Torisawa Shinsuke, Fukuda Hiromu, Ishibashi Yasunori, Suzuki Katsuya, Yamane Takeshi, Sawada Yoshifumi, Okada Tokihiko, Miyashita Shigeru
    Mathematical and Physical Fisheries Science 4 2 - 6 2006年 [査読無し][通常論文]
  • 鈴木 勝也, 髙木 力, 宮下 和士
    数理水産科学 4 23 - 28 数理水産科学研究会 2006年 [査読無し][通常論文]
  • Video analysis of the schooling behavior of juvenile chum salmon under light and dark conditions using a mathematical model
    Katsuya SUZUKI, Tsutomu TAKAGI, Kazushi MIYASHITA
    NPAFC Technical Report 7 131 - 132 2006年 [査読無し][通常論文]
  • 髙木 力, Shimizu Takashi, Holger Korte, Hiraishi Tomonori, Yamamoto Katsutaro
    Fisheries Research 76 1 67 - 80 2005年10月 [査読有り][通常論文]
     
    We have developed a system called net shape and loading analysis system (NaLA) for determining fishing net configuration and load analysis, and have used it to estimate the dynamic behaviour of actual fishing gear, such as gill nets and aquaculture fish farm nets. In this study, we have refined the NaLA calculation model for application to drift gill nets by introducing additional gear components besides netting and by considering environmental factors, such as waves. The primary objective of this paper was to evaluate the utility of the refined system and examine how accurately it simulates the actual behaviour of a drift gill net by comparing the predictions with measured data. Ten observations to obtain in situ data were recorded between May and June 2003 while assessing salmonid and other pelagic fish stocks in the northwest Pacific. During these operations, the horizontal and vertical displacements of the net were measured using mobile GPS and depth sensors over 10 h soak times. Then, the simulated results of the shape and motion of the gear were compared with the measured horizontal and vertical displacements. There was close agreement between the simulated and measured behaviour of the gear, and we proved that the refined NaLA method can simulate the shape and motion of an actual drift gill net with good accuracy, if the field conditions are accurately input to the calculation. (c) 2005 Elsevier B.V. All rights reserved.
  • Application of Net shape simulator “NaLA” to gill net
    T SHIMIZU, T TAKAGI, K SUZUKI, T HIRAISHI, K YAMAMOTO
    Contributions on the Theory of Fishing Gears and Related Marine Systems 4 29 - 36 2005年10月 [査読有り][通常論文]
  • Possibilities of integrative analysis using net shape simulator “NaLA” and CFD for estimation of flow characteristics near fishing net,
    T TAKAGI, H YOSHINO, T SHIMIZU, K SUZUKI
    Contributions on the Theory of Fishing Gears and Related Marine Systems 3 245 - 250 2005年10月 [査読有り][通常論文]
  • バイオロギングとバイオメカニクスの総合研究によるヒラメのtailbeat-and-glide行動の解析
    髙木 力, 河邊玲
    第36回北洋シンポジュウム 2  2005年02月 [査読無し][通常論文]
     
    海洋生態系における高次捕食者の行動研究のための新技術
  • 鈴木 勝也, 髙木 力, 鳥澤 眞介, 福田 漠生, 村田 修, 山本 眞司, 宮下 和士
    数理水産科学 3 15 - 20 数理水産科学研究会 2005年 [査読無し][通常論文]
  • 鈴木 勝也, 高木 力, 宮下 和士
    日本水産工学会学術講演会講演論文集 16 195 - 196 2004年 [査読無し][通常論文]
  • 異なる光環境下における魚群の行動特性について
    鈴木 勝也, 高木 力, 鳥澤 眞介, 宮下 和士
    数理水産科学 2 37 - 42 2004年 [査読無し][通常論文]
  • K Suzuki, T Takagi, T Shimizu, T Hiraishi, K Yamamoto, K Nashimoto
    FISHERIES SCIENCE 69 4 695 - 705 2003年08月 [査読有り][通常論文]
     
    The aim of the present study was to develop a numerical calculation method to simulate the three-dimensional dynamic behavior of fishing nets. In a previous study, we presented a formulation to calculate net configurations. In this method, fishing nets were modeled as a group of lumped mass points interconnected with springs that have no mass. To verify the validity of calculation results using a computational model, we performed the flume tank experiments with a rectangular net and compared results with those of the numerical simulation of experiments. Using our method, numerical calculations for a rectangular net in a steady flow can provide accurate results. The calculated load and tension force distribution of the flat net were generally in accordance with the results of the flume tank experiments. This study shows that our method is valid for the simulation of fishing nets; furthermore, we have resolved earlier problems that were associated with this model.
  • 漁具性能の科学的性能(漁具工学の数値シミュレーション技術とその可能性について
    髙木 力
    日本水産工学会講演論文集 247 - 248 2003年05月 [査読無し][通常論文]
  • 髙木 力, Shimizu Takashi, Suzuki Katsuya, Hiraishi Tomonori, Matsushita Yoshiki, Watanabe Toshihiro
    水産工学 40 2 125 - 134 日本水産工学会 2003年 [査読無し][通常論文]
     
    著者らは水中での網地形状と荷重をコンピュータによって推定できる汎用性の高いシステム"NaLA"(Net shape configuration and Loading Analysis system)の実用化を目指してその開発に取り組んでいる。網地形状と荷重は数値計算により算定されパーソナルコンピュータ上に3次元的に視覚化される。本論文ではNaLAによって得られた推定結果を水槽実験とトロール網形状推定ソフトウェアDynamiTと比較し、その性能を評価した。計算モデル内の抗力係数をレイノルズ数の関数とすることで網地の形状とそれに作用する荷重は水槽実験の結果とよく一致することが確認された。NaLAとDynamiTとの性能を比較したところ、NaLAでは早い段階で平衡状態の網形状を得ることができたが、DynamiTでは網地の脚や曳航索が折れ曲がり、網形状が不安定な状態になることが確認され不合理な結果が得られた。これらの結果からNaLAの計算モデルで得られる推定結果は精度、汎用性や実用性の面でより適切なものであることが確
  • 閉鎖空間内における魚群行動の確率モデル
    鈴木 勝也, 高木 力, 守冨 裕, 鳥澤 眞介, 宮下 和士
    数理水産科学 1 15 - 20 2003年 [査読無し][通常論文]
  • T Takagi, K Suzuki, T Hiraishi
    NIPPON SUISAN GAKKAISHI 68 3 320 - 326 2002年05月 [査読有り][通常論文]
     
    Our objective is to develop a numerical calculation method for simulating the three-dimensional dynamic behavior of fishing nets. For the numerical calculation, the fishing nets are modeled as a group of lumped point masses interconnected with springs without mass. Point masses are arranged at each knot or at the center of each mesh bar. Equations of motion for all point masses are derived, and then a net shape can be estimated at each time step by numerically solving these equations. The numerical calculation of the dynamic behavior of a rectangular net in steady flow can provide good results by using the presented formulation. The magnitude of tension force applied to the mesh bars can be observed as the change in the colors of the mesh bars. As a calculated net shape can be viewed as a three-dimensional image from an arbitrary visual point and also the net shape image can be enlarged, the net shape and the tension force distribution can be investigated in more detail.
  • Tsutomu Takagi, Katsuya Suzuki, Tomonori Hiraishi
    Fisheries Science 68 sup2 1857 - 1860 2002年 [査読有り][通常論文]
     
    For the numerical calculation, the fishing net is modeled as a group of lumped point masses interconnected with springs without mass. The numerical calculation of the dynamic behavior of a net in steady flow can provide good results when using the formula presented. The magnitude of applied tension force to the mesh bars can be observed as the change in the colors of the mesh bars. To observe the net shape qualitatively, it is sufficient to set the number of calculation points equal to the number of knots of fishing net. However, when the tension forces of the mesh bars are estimated, it is necessary to carefully obtain the appropriate coefficients of fluid dynamic force and also to set point masses over the net. © 2002, The Japanese Society of Fisheries Science. All rights reserved.
  • Calculation and visualization method of dynamic fishing net shape
    Tsutomu TAKAGI, Katsuya SUZUKI, Tomonori HIRAISHI
    Contributions on the Theory of Fishing Gears and Related Marine Systems 2 159 - 172 2001年11月 [査読有り][通常論文]
  • 鈴木 勝也, 守冨 裕, 高木 力, 山根 猛, 村田 修
    日本水産工学会学術講演会講演論文集 13 177 - 178 2001年 [査読無し][通常論文]
  • 高木 力, Tsutomu Takagi, Faculty of Agriculture Kinki University
    日本水産学会誌 = Bulletin of the Japanese Society of Scientific Fisheries 66 5 901 - 902 The Japanese Society of Fisheries Science 2000年09月15日
  • 円柱構造物に対する魚群の遊泳行動
    鈴木 勝也, 高木 力, 山根 猛
    日本水産工学会学術講演会講演論文集 221 - 222 2000年 [査読無し][通常論文]
  • 高木 力, Tsutomu Takagi, Faculty of Agriculture Kinki University
    日本水産学会誌 = Bulletin of the Japanese Society of Scientific Fisheries 65 5 925 - 926 The Japanese Society of Fisheries Science 1999年09月15日
  • K NASHIMOTO, K SUZUKI, T TAKAGI, K MOTOMATSU, T HIRAISHI
    NIPPON SUISAN GAKKAISHI 61 4 525 - 530 1995年07月 [査読有り][通常論文]
     
    Fishing of whelks Neptunea arthritica in Shiriuchi, Hokkaido is carried out using three types of trap. However, the size selectivity of these traps is not known. Size selectivity significantly depends on the mesh size and hanging ratio of the bottom net of the trap. In this study the size selectivity curve of traps for whelks was estimated by calculating the probability of retention (P-n) that entrapped whelks can not pass through the bottom net of a trap. P-n is expressed as a function of mesh bar length l, hanging ratio alpha and shell length L'. The results of an examination of 48 individuals with alpha values of either 0.50 or 0.29 indicate that P-n can be expressed as a partial sigmoid curve. The regression curve can be expressed approximately as: When alpha=0.05, P-n=2/1+e(2.7-6.40(L'/2l) -1, When alpha=0.29, P-n=2/1+e(3.78-7.50(L'/2l) -1. where L' is the measured shell length. The slope of the latter is greater than that of the former and the values of the selection span (the difference of L'/2l between 25% and 75%) are 0.22 when alpha = 0.50 and 0.19 when alpha = 0.29. The resultant selection factors are 0.60 for the former and 0.65 for the latter.
  • T HIRAISHI, K NASHIMOTO, T TAKAGI, K SUZUKI, K MOTOMATU
    NIPPON SUISAN GAKKAISHI 61 3 363 - 368 1995年05月 [査読有り][通常論文]
     
    To estimate and control the water current velocity at the bottom of a net cage for aquaculture of benthic fishes, it is necessary to know the stationary-holding ability of the fish in the net. In this experiment, bastard halibut Paralichthys olivaceus and dead longsnout flounder Limanda punctatissima were used. A net was laid horizontally inside a small flume tank. Then the fish was carefully placed inside in such a way that its body axis was parallel to the stream line and its head was at the upper stream side. For bastard halibut, each fish was allowed to stay approximately 5 minutes in the tank. A slow water current was applied and increased gradually. The current velocity at the time when the fish slipped and could not hold the same position inside, was recorded and termed as the slipping speed. The coefficient of static friction between the fish body and the net plane was calculated by the angle of the slope. The relationship between total length l and slipping speed u(s) was expressed by the function u(s) = k3square-root(l) in both two species. The value of proportional constant k3 was 3.2 (cm/s2)1/2 in bastard halibut, 3.3 (cm/s2)1/2 longsnout flounder. For bastard halibut of 1.0 kgf weight and 45 cm total length, the average slipping speed was 21 cm/s.
  • K NASHIMOTO, K MATSUYAMA, T HIRAISHI, T TAKAGI
    NIPPON SUISAN GAKKAISHI 60 1 79 - 83 1994年01月 [査読有り][通常論文]
     
    Hydraulic jet dredges have been used recently for catching Japanese surf clam in Hokkaido. The catching efficiency of this kind of fishery needs to be clarified. An attempt was made to estimate the catch efficiency of the Japanese surf clam hydraulic jet dredge which is being used in Tomakomai sea area. The dredge survey was carried out four times using two dredges towed simultaneously in the same fishing ground. One dredge was towed behind the other at an interval of 270 cm. The number of shells caught by the dredge was counted and their shell length was measured. Under the condition of the dredging survey, the catching efficiency in a shell length class is considered to be a function of the ratio of clams caught by the front dredge to the number of shells caught by the rear dredge. In this way, the fishing efficiency for hydraulic jet dredge was evaluated. However, the average catch efficiency of hydraulic dredge for Japanese surf clam may be slightly influenced by towing speed. In our survey, at a towing speed ranging between 2.90 m/min-4.78 m/min, the average catch efficiency obtained was 0.63.
  • T TAKAGI, K NASHIMOTO, K YAMAMOTO, T HIRAISHI
    NIPPON SUISAN GAKKAISHI 59 8 1279 - 1287 1993年08月 [査読有り][通常論文]
     
    This paper describes the influence of water tank shape and size on the schooling behavior of fish. In this experiment, we used two dimensional water tanks of two different shapes, i.e. circular and square, of various diameters and side lengths between 50 and 125cm. Fish schooling behavior was expressed mathematically in terms of the Sannomiya and Matuda model which comprises of seven linear forces influencing fish behavior. The results showed that all forces except the propulsive force were independent of tank size and that schooling and attractive forces against the walls were strongest in the circular tanks. The random force was greatest in magnitude, accounting for approximately 60-75% of the total, followed by the repulsive force to the walls and the schooling force which affected fish schooling behavior. Fish schooling in square tanks tended to behave irregularly and remain in the tank corners.

書籍

  • Contributions on the theory of fishing gears and related, Marine systems
    2002年
  • 漁具物理学
    成山堂書店 2001年
  • Fishing Gear Phisics
    2001年
  • Contributions on the Theory of Fishing Gears and Related Marine Systems
    NEUER HOCHSCHULSCHRIF TENVIRLAG 2000年

その他活動・業績

  • 阿部悟, 高木力, 米山和良, 鳥澤眞介, 波部斉, 阿部孝司, 井口信和, 竹原幸生, 升間主計, 八木洋樹, 中井彰治, 山口武治, 浅海茂 日本水産学会大会講演要旨集 2019 11 2019年03月26日 [査読無し][通常論文]
  • 土井慧祐, 青木勇樹, 鳥澤眞介, 光永靖, 高木力 日本水産学会大会講演要旨集 2018 5 2018年09月15日 [査読無し][通常論文]
  • 中村暢佑, 米山和良, 刀祢和樹, 高木力, CHIANG Wei‐Chuan, YEH Hsin‐Ming, LU Ching‐Ping, WANG Sheng‐Ping, 阪倉良孝, 中村乙水, 河邊玲 日本水産学会大会講演要旨集 2018 40 2018年03月26日 [査読無し][通常論文]
  • 高木力, 米山和良, 阿部悟, 鳥澤眞介, 竹原幸生, 山口武治, 浅海茂 日本水産工学会学術講演会講演論文集 2017 247‐248 2017年05月27日 [査読無し][通常論文]
  • 阿部悟, 高木力, 竹原幸生, 木村暢夫, 平石智徳, 米山和良, 鳥澤眞介, 山口武治, 浅海茂 日本水産学会大会講演要旨集 2017 155 2017年03月26日 [査読無し][通常論文]
  • 阿部悟, 高木力, 竹原幸生, 木村暢夫, 平石智徳, 米山和良, 鳥澤眞介, 浅海茂 日本水産学会大会講演要旨集 2016 10 2016年03月26日 [査読無し][通常論文]
  • 不破 茂, 胡 夫祥, 高木 力, 山根 猛 日本水産學會誌 = Bulletin of the Japanese Society of Scientific Fisheries 78 (5) 1013 -1013 2012年09月15日
  • Minoru Kadota, Shinsuke Torisawa, Tsutomu Takagi, Kazuyoshi Komeyama, Hiromu Fukuda FISHERIES SCIENCE 78 (1) 207 -207 2012年01月 [査読無し][通常論文]
  • Tsutomu TAKAGI, Katsuya SUZUKI, Shinsuke TORISAWA, Kazuyoshi KOMEYAMA, Minoru KADOTA, Shigeru ASAUMI Contributions on the Theory of Fishing Gears and Related Marine Systems 7 261 -272 2011年 [査読無し][通常論文]
  • There-Dimensional Monitoring of Pacific Bluefin Tuna cultured in an Off Shore Net Cage using a Digital Stereo Camera System.
    Shinsuke TORISAWA, Minoru KADOTA, Kazuyoshi KOMEYAMA, Tsutomu TAKAGI, Takeshi YAMANE Contributions on the Theory of Fishing Gears and Related Marine Systems 7 25 -34 2011年 [査読無し][通常論文]
  • 永松 公明, 高木 力, 山根 猛, 井上 悟, 浅海 茂, 沼口 隆之, 小林 次彦 日本水産工学会学術講演会講演論文集 22 113 -114 2010年05月22日
  • There-dimensional monitoring for free-swimming Pacific bluefin tuna cultured in a net cage using a digital stereo-video camera system.
    Shinsuke TORISAWA, Minoru KADOTA, Kazuyoshi KOMEYAMA, Katsuya SUZUKI, Tsutomu TAKAGI Proceedings of IFREMER International symposium 2010 115 -118 2010年 [査読無し][通常論文]
  • 米山和良, 鈴木勝也, 高木力, 山根猛, 光永靖, 平石智徳 日本水産学会大会講演要旨集 2008 174 2008年03月27日 [査読無し][通常論文]
  • 米山和良, 鈴木勝也, 高木力, 山根猛, 光永靖, 平石智徳 日本水産学会大会講演要旨集 2007 3 2007年03月28日 [査読無し][通常論文]
  • 福田 漠生, 鳥澤 眞介, 高木 力, 松田 征也, 山根 猛 日本水産工学会学術講演会講演論文集 18 315 -316 2006年06月10日
  • 河邊 玲, 高木 力 水産海洋研究 70 (2) 132 -249 2006年05月 [査読無し][通常論文]
  • 田村 優美子, 高木 力 近畿大学農学部紀要 39 75 -77 2006年03月31日 
    The morphology of bluefin tuna (Thunnus orientalis) contributes greatly to high-speed swimming with oscillating the fin at high frequency so called thunniform mode. The form of the body, fusiform, result in small resistance force because the pressure drag is less than that of a bluff body shape. The main propulsion and the lift force are produced by the caudal fin and the pectoral fins, respectively. However the fluid dynamic characteristics of bluefin tuna are not clarified accurately. In this study, the fluid dynamics of bluefin tuna such as drag and lift force and velocity fields around the body were evaluated by using CFD (computational fluid dynamics) analysis.The drag and lift force are 79.2% (.0.076 N) and 129% (0.124 N) of the submerged weight, respectively and the momentum to the gravity centre is 0, if the flow speed amounts 2.6BL/s (0.75m/s) with a 0 degree angle of attack. We show pressure on body surface on a figure. There is no vortex and turbulent flow around the body because of its fusiform.記事区分:原著
  • クロマグロ(Thunnus orientalis)幼魚の魚群行動に与える照度の影響
    福田 漠生, 鳥澤 眞介, 石橋 泰典, 倉田 道雄, 澤田 好史, 鈴木 勝也, 高木 力 近畿大学農学部紀要 39 88 -92 2006年 [査読無し][通常論文]
  • 畑山 純, 光永 靖, 高木 力, 山根 猛, 住田 祐里, 松谷 茂 日本水産工学会学術講演会講演論文集 17 3 -4 2005年05月28日
  • 清水 孝士, 高木 力, 鉛 進, 青木 仁, 桐山 智, 舘 昌廣, 伏島 一平, 稲田 博史, 平石 智徳, 山本 勝太郎 日本水産工学会学術講演会講演論文集 17 111 -112 2005年05月28日
  • 清水 孝士, 高木 力, 平石 智徳 数理水産科学 3 86 -91 2005年
  • The Development of Visual Acuity in Pacific bluefin Tuna
    Shinsuke Torisawa, Tsutomu Takagi, Yasunori Ishibashi, Yoshifumi Sawada, Takeshi Yamane Memoirs of the faculty of agriculture of Kinki University 38 182 -186 2005年 [査読無し][通常論文]
  • T Takagi, Y Moritomi, J Iwata, H Nakamine, N Sannomiya ICES JOURNAL OF MARINE SCIENCE 61 (7) 1214 -1223 2004年10月 [査読無し][通常論文]
     
    We investigated the validity of a mathematical model to describe fish schooling behaviour towards a simple set-net model. We apply a model considered to be "an autonomous decentralized system" and based on Newton's equation of motion. It includes the parameter M, which indicates "the quantity of information exchange" (i.e. the number of neighbours that affect an individual's behaviour) and strongly affects fish school size and schooling behaviour in an enclosed space. To evaluate the model, simulations of fish schooling behaviour in a set-net model consisting of a leading fence and a box-shaped trap similar to a primitive type of set-net were compared with experimentally observed behaviour of bitterling and mackerel, with a focus on M. A small M induces improper behaviour because there is low cooperation among fish in a school. On the other hand, if M is too large, improper simulation results of individuals in deadlock states in the trap are obtained as a result of excessive information exchange among the fish. The results suggest that the mathematical model can describe the behaviour in a set-net model adequately when M is greater than 2 and less than 10. (C) 2004 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
  • T Shimizu, T Takagi, K Suzuki, T Hiraishi, K Yamamoto FISHERIES SCIENCE 70 (3) 401 -411 2004年06月 [査読無し][通常論文]
     
    The purpose of the present paper was to describe the dynamic behavior of gill nets using the computer-aided simulation NaLA (net shape and loading analysis), a system that was developed for determining net shape and load. The general calculation model of the system was refined after considering gill net construction and the environment during operation, such as wave motion and the boundary conditions of the water surface and bottom. This method models a gill net as a group of lumped masses interconnected by springs without mass, which are arranged as knots, mesh bars, netting lines, and other rigging components. Equations of motion are then derived for each lumped mass point. Net shape, mesh opening angle, and tension distribution are estimated at each time-step by using a PC to solve the system of equations. To examine the applicability of the refined calculation model of NaLA to gill nets, experiments were conducted with a gill net in a water channel. The experimental and calculated net shape, loading, and mesh opening angles were compared. The results agreed well, confirming that the refined calculation model of NaLA for gill nets is applicable to estimate the dynamic behavior of gill nets.
  • 清水 孝士, 高木 力, 阿部 友彦, 山下 成治, 平石 智徳, 山本 勝太郎 日本水産工学会学術講演会講演論文集 16 153 -154 2004年05月29日
  • 高木 力, 藤田 直子, 山根 猛 日本水産工学会学術講演会講演論文集 16 143 -144 2004年05月29日
  • 高木 力, 田村 優美子, 河邊 玲 数理水産科学 2 43 -50 2004年
  • 衝突多発期におけるクロマグロ幼魚の群行動特性
    鳥澤 眞介, 高木 力, 福田 漠生, 鈴木 勝也 数理水産科学 2 128 -129 2004年 [査読無し][通常論文]
  • Tsutomu Takagi, Takashi Shimizu, Katsuya Suzuki, Tomonori Hiraishi, Katsutaro Yamamoto Fisheries Research 66 (2-3) 235 -243 2004年 [査読無し][通常論文]
     
    in press
  • 高木 力, 清水 孝士, 鈴木 勝也 日本水産工学会誌 41(1),53-58 (1) 53 -59 2004年 [査読無し][通常論文]
     
    In order to estimate fishing net configuration and load numerically and visualize them dynamically in 3-D images using a PC, we have developed "NaLA", which is a system for determining net shape configuration and load. The numerical simulation system can provide useful information to fishermen, fishing gear manufactures and researcher for evaluating fish stocks, since, in general, it is not easy to fully understand shapes of fishing nets underwater and the influence of the dynamic behavior of a fishing net gear on capture processes. In this report, numerical simulation methods about fishing net configuration, which have been developed by other research institutes, are reviewed, the outline of NaLA and examples of computational results by NaLA are introduced and we consider the role and potentiality for the numerical simulation technique to estimate fishing net configuration and load.
  • K Suzuki, T Takagi, T Shimizu, T Hiraishi, K Yamamoto, K Nashimoto FISHERIES SCIENCE 69 (5) 1084 -1084 2003年10月 [査読無し][通常論文]
  • 高木 力, 吉野 博之, 河邊 玲 数理水産科学 1 77 -80 2003年
  • K Suzuki, T Takagi, T Hiraishi FISHERIES RESEARCH 60 (1) 3 -10 2003年01月 [査読無し][通常論文]
     
    The schooling behavior of the fish Parapristipom trilineatum (chicken grunt) was examined for a range of school sizes in a water tank containing a central columnar structure using a mathematical model of fish schooling behavior that was modified from that of Sannomiya and Matuda. The two-dimensional motion of individuals was captured on digital video over about 10 min, and these time-series data were used to tune the model to the experimental conditions. The model parameters were then used to evaluate schooling behavior quantitatively. Comparing force magnitudes between experimental conditions revealed that propulsive force was less in a tank without the central structure than in a tank with the central structure, under all conditions tested. These results indicate that the school was less active under unobstructed conditions. Propulsive force also decreased with increasing school size. Attractive and repulsive forces of the walls were dominant for smaller school sizes; the attractive and repulsive forces of the structure were significant only for the largest school tested (25 individuals). Thus, changes in behavioral patterns caused by the number of individuals or the presence of structures can be expressed using the mathematical model. (C) 2002 Elsevier Science B.V. rights reserved.
  • 高木 力, 清水 孝士, 鈴木 勝也, 平石 智徳, 山本 勝太郎, 梨本 勝昭 日本水産工学会学術講演会講演論文集 14 133 -134 2002年05月24日
  • Tsutomu Takagi, Katsuya Suzuki, Tomonori Hiraishi 日本水産学会誌 68 (3) 320 -326 2002年 [査読無し][通常論文]
     
    Our objective is to develop a numerical calculation method for simulating the three-dimensional dynamic behavior of fishing nets. For the numerical calculation, the fishing nets are modeled as a group of lumped point masses interconnected with springs without mass. Point masses are arranged at each knot or at the center of each mesh bar. Equations of motion for all point masses are derived, and then a net shape can be estimated at each time step by numerically solving these equations. The numerical calculation of the dynamic behavior of a rectangular net in steady flow can provide good results by using the presented formulation. The magnitude of tension force applied to the mesh bars can be observed as the change in the colors of the mesh bars. As a calculated net shape can be viewed as a three-dimensional image from an arbitrary visual point and also the net shape image can be enlarged, the net shape and the tension force distribution can be investigated in more detail.
  • Contributions on the theory of fishing gears and related, Marine systems
    2 2002年 [査読無し][通常論文]
  • 高木 力, 鈴木 勝也 日本水産工学会学術講演会講演論文集 13 161 -162 2001年05月31日
  • 光永靖, 鈴木勝也, 高木力, 山根猛 日本水産学会大会講演要旨集 2001 39 2001年04月01日 [査読無し][通常論文]
  • 高木 力 水産工学 37 (2) 99 -105 2000年12月01日
  • 水産工学会誌 36 (1) 71 -74 1999年 [査読無し][通常論文]
  • Theoretically Prediction of the Wave Exciting Force and Hydrodynamic Coefficients on a Raft for an Aquacutural Net Cage
    日本水産工学会誌 Vol.35 1999年 [査読無し][通常論文]
  • Theoretically Prediction of the Wave Exciting Force and Hydrodynamic Coefficients on a Raft for an Aquacutural Net Cage.
    Fisheries Engineering 35 (3) 271 -281 1999年 [査読無し][通常論文]
  • 水産工学会誌 35 (2) 153 -158 1998年 [査読無し][通常論文]
  • 高木 力, 平石 智徳, 山本 勝太郎, 梨本 勝昭 水産工学 34 (1) 23 -32 1997年 [査読無し][通常論文]
     
    蓄養殖施設を設置するための静穏域を造成する波浪制御構造物として没水平板構造物に注目し、その波浪制御機能の有効性について検討を加えた。対象とする平板の形状は短形とし、その大きさ、設置条件、入射波条件を変化させた。構造物周辺の波浪変形をハイブリッド法を適用して3次元線形ディフラクション問題を解くことによって算出し、比較検討した。計算の結果、平板の背後に帯状の波高域が形成された。平板の幅および没水深を水深のそれぞれ2倍以上、30%以浅、また平板傾斜角を30℃以上とることによってH/Hi≦0.6(H:計算点での波高、Hi:入射波高)の領域が増大することが示唆された。
  • 平石 智徳, 梨本 勝昭, 高木 力, 鈴木 健吾, 本松 敬一郎 日本水産学会誌 61 (3) 363 -368 1995年 [査読無し][通常論文]
     
    To estimate and control the water current velocity at the bottom of a net cage for aquaculture of benthic fishes, it is necessary to know the stationary-holding ability of the fish in the net. In this experiment, bastard halibut Paralichthys olivaceus and dead longsnout flounder Limanda punctatissima were used. A net was laid horizontally inside a small flume tank. Then the fish was carefully placed inside in such a way that its body axis was parallel to the stream line and its head was at the upper stream side. For bastard halibut, each fish was allowed to stay appoximately 5 minutes in the tank. A slow water current was applied and increased gradually. The current velocity at the time when the fish slipped and could not hold the same position inside, was recorded and termed as the slipping speed. The coefficient of static friction between the fish body and the net plane was calculated by the angle of the slope. The relationship between total length l and slipping speed uswas expressed by the function us= k3in both two species. The value of proportional constant k3was 3.2 (cm/s2)1/2 in bastard halibut, 3.3 (cm/s2)1/2 longsnout flounder. For bastard halibut of 1.0 kgf weight and 45 cm total length, the average slipping speed was 21 cm/s. © 1995, The Japanese Society of Fisheries Science. All rights reserved.
  • 梨本 勝昭, 鈴木 健吾, 高木 力, 本松 敬一郎, 平石 智徳 日本水産学会誌 61 (4) 525 -530 1995年 [査読無し][通常論文]
     
    Fishing of whelks Neptunea arthritica in Shiriuchi, Hokkaido is carried out using three types of trap. However, the size selectivity of these traps is not known. Size selectivity significantly depends on the mesh size and hanging ratio of the bottom net of the trap. In this study the size selectivity curve of traps for whelks was estimated by calculating the probability of retention (P„) that entrapped whelks can not pass through the bottom net of a trap. P„ is expressed as a function of mesh bar length l, hanging ratio a and shell length L’. The results of an examination of 48 individuals with a values of either 0.50 or 0.29 indicate that Pncan be expressed as a partial sigmoid curve. The regression curve can be expressed approximately as: where L’ is the measured shell length. The slope of the latter is greater than that of the former and the values of the selection span (the difference of L’/2l between 25% and 75%) are 0.22 when α = 0.50 and 0.19 when α = 0.29. The resultant selection factors are 0.60 for the former and 0.65 for the latter. © 1995, The Japanese Society of Fisheries Science. All rights reserved.
  • 水産工学会誌 32 (1) 39 -43 1995年 [査読無し][通常論文]
  • 水産工学会誌 32 (2) 127 -135 1995年 [査読無し][通常論文]
  • 梨本 勝昭, 松山 恵二, 平石 智徳, 高木 力 日本水産学会 60 (1) 79 -83 1994年 [査読無し][通常論文]
     
    Hydraulic jet dredges have been used recently for catching Japanese surf clam in Hokkaido. The catching efficiency of this kind of fishery needs to be clarified. An attempt was made to estimate the catch efficiency of the Japanese surf clam hydraulic jet dredge which is being used in Tomakomai sea area. The dredge survey was carried out four times using two dredges towed simultaneously in the same fishing ground. One dredge was towed behind the other at an interval of 270 cm. The number of shells caught by the dredge was counted and their shell length was measured. Under the condition of the dredging survey, the catching efficiency in a shell length class is considered to be a function of the ratio of clams caught by the front dredge to the number of shells caught by the rear dredge. In this way, the fishing efficiency for hydraulic jet dredge was evaluated. However, the average catch efficiency of hydraulic dredge for Japanese surf clam may be slightly influenced by towing speed. In our survey, at a towing speed ranging between 2.90 m/min~4.78 m/min, the average catch efficiency obtained was 0.63. © 1994, The Japanese Society of Fisheries Science. All rights reserved.
  • 養殖網生簀の係留技術に関する模型実験による検討
    北大水産彙報 45 (1) 9 -18 1994年 [査読無し][通常論文]
  • 相模湾におけるマアジの標識放流について
    南西外海の資源・海洋研究 (8) 29 -37 1992年 [査読無し][通常論文]
  • 高木 力, 梨本 勝昭, 山本 勝太郎, 平石 智徳 日本水産学会誌 59 (8) 1279 -1287 1992年 [査読無し][通常論文]

特許

  • 特許3870359:網地形状シミュレーションプログラム,漁網シミュレーションプログラム, 漁撈シミュレーションプログラム並びに漁撈コントロールシステム 特許第3870359号  
    髙木 力

受賞

  • 2015年03月 日本水産学会 水産学技術賞
     
    受賞者: 髙木 力
  • 2006年 the Third International Symposium on Aero Aqua Bio-Mechanisms ベストプレゼンテーションアワード
     Functional morphology of swimming bluefin tuna based on CFD analysis:I. Effects of morphology on hydrodynamic characteristics 
    受賞者: 田村優美子;髙木 力;山根 猛
  • 2004年 PICESベストポスタープレゼンテーション賞(共著)
  • 2000年 水産工学奨励賞(日本水産工学会)

共同研究・競争的資金等の研究課題

  • 魚群行動の流体力学的機能性の解明
    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 : 2020年04月 -2023年03月 
    代表者 : 鳥澤 眞介, 竹原 幸生, 高木 力
  • 情報科学と画像解析を応用した新技術展開による養殖魚成育生産管理システムの開発
    日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2018年04月 -2022年03月 
    代表者 : 高木 力, 竹原 幸生, 鳥澤 眞介, 阿部 孝司, 米山 和良, 井口 信和
     
    魚類養殖産業では生産物が水面下にあるため日常的に求められる生産管理や成育状態の把握が困難となっている。こうした背景からICT導入による効率化が検討されている。 本研究では,魚類養殖の成育・生産を効率化するシステムの構築を目指して,非接触で養殖魚の収容数や生育状態を計測する基盤技術開発に取り組む。 【個体数計数システムの開発】本システムは取得された画像情報から個体画像を抽出する過程とその個体画像を連続画像上で追跡し,各個体の移動ベクトルを推定する二つの解析パートで構成されている。H30年度は,生簀内を遊泳する養殖魚を撮影した画像情報から個体画像を抽出するアルゴリズムの基盤部分の構築を行った。深層学習による個体画像識別の有効性を確認した。検出対象を塗り分けた画像と元画像をペアとした教師データを用いて検出対象を画像的に識別するSegNetとよばれる深層学習法を適用することにより,養殖魚の個体画像を関心領域として抽出することを行った。その結果,実験水槽レベルでは学習画像データ100枚を用いて,2層構造SegNetを適用することで個体画像抽出が可能となった。この成果を実海域に応用することによりクロマグロ養殖場での養殖魚個体の画像抽出を行い,最適なSegNetの学習パラメータを探索する。 【非接触型個体サイズ推定システムの開発】DLT法を用いて複数のカメラから三次元位置座標を推定し,養殖魚の尾叉長等の成長状態を把握するシステムの開発を行った。直方体状キャリブレーションフレームを用いてカメラシステムを較正し計測誤差を抑制した。これにより養殖魚の体サイズは直接生簀から捕獲せずに,非接触で体サイズを定量化することができる。直接計測したものと本方法から算定された結果を比較したところ,直接計測との有意差は認められず本方法の有効性を確認することができた。
  • 日本学術振興会:科学研究費助成事業 挑戦的萌芽研究
    研究期間 : 2015年04月 -2017年03月 
    代表者 : 木村 暢夫, 米山 和良, 鳥澤 眞介, 平石 智徳, 高木 力, 竹原 幸生
     
    養殖生簀内の飼育個体数を簡便に計数可能な基盤技術を開発する目的で,流体工学分野で適用されている流場の可視化技術であるPTV(Particle Tracking Velocimetry)解析技術を適用し,画像内の魚群の構成尾数を計数する基盤アルゴリズムを構築した。動画像内の一定の輝度と面積以上の領域を魚の個体として領域抽出したのち,当該領域の移動ベクトルをカルマンフィルタのアルゴリズムを適用することにより算定した。ベクトルの本数から空間内の個体数を推定したところ,水槽内に200尾を投入したとき,個体数推定結果の実数に対する平均誤差は5.9%となり,その有効性が確認できた。
  • 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 : 2014年04月 -2017年03月 
    代表者 : 高木 力, 鳥澤 眞介, 光永 靖, 河邊 玲, 門田 実, 米山 和良
     
    旋網漁具の動態を数値シミュレーション技術を用いて解析するとともに,対象魚類の三次元行動軌跡を構築することにより,カツオ・マグロ類を対象とした旋網漁業の漁獲メカニズムを評価した。メバチ3個体の操業中の行動軌跡を取得した。投網後,個体が旋網に取り巻かれてからは個体の移動ベクトルの方向は鉛直・水平方向に短時間で大きく変動した。漁具の動態解析結果から網裾の最大到達深度は200mに達する一方で個体は100m以浅を遊泳し,網を締め巻き始めてからは遊泳速度は30%減少した。投網後1500秒経過すると,網地目合が縦方向に伸長されるため,メバチの若齢魚は身網の半分以上で通過不可能となることが示唆された。
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2011年04月 -2014年03月 
    代表者 : 稲田 喜信, 高信 英明, 高木 力
     
    小型の飛翔体や地上移動型ロボットを用いた情報収集をより高機能にすることを目的として多数の機体を連携させる群制御の研究を行った。自然界における鳥や魚の群運動を参考にして、接近、反発、平行移動の3つの制御を組み合わせた群制御モデルを作成し、これを用いて地上移動型ロボットや各種飛翔体を用いた群制御を試みた。その結果、これらのハードウェア上で3つの制御の全て、あるいは一部が正しく機能することを確認し、飛行船と地上移動ロボットという異種の機体間での連携制御にも成功した。また、魚群行動を分析して個体の成長段階に応じた群形成パラメータの変化を確認し、群移動時のエネルギ消費を低減できる個体配置を明らかにした。
  • 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 : 2010年 -2012年 
    代表者 : 高木 力, 米山 和良, 鳥澤 眞介, 鈴木 勝也, 河邊 玲, 門田 実
     
    本研究はクロマグロ用沖合型養殖施設を力学的なだけでなく,養成魚の行動特性も考慮して最適設計するための知見を得ようとするものである。施設の力学的解析を行うために施設形状と作用荷重を推定する数値シミュレーション手法を開発した。これにより,1ktの潮流により生簀内容積がおよそ50%減少することがわかった。また,強い潮流により生簀網が吹け上がり養成魚と接触する危険性が高まることが行動観測により示唆されたほか,これに伴う冷水塊の進入が養成魚の行動に強い制限を加えることがわかった。
  • 日本学術振興会:科学研究費助成事業 研究活動スタート支援
    研究期間 : 2009年 -2010年 
    代表者 : 米山 和良, 高木 力, 鳥澤 眞介, 鈴木 勝也, 門田 実
     
    本研究では、浮沈式沖合養殖施設内においてクロマグロの養成に必要な情報となる行動記録の計測を実施し、養成環境の変化に対するクロマグロの反応行動を分析した。本研究では、冷水塊の差し込みによる養魚の顕著な遊泳深度の変化をとらえた。また、養魚の3次元遊泳経路の計測に成功し、浮沈操作による養成空間の強制的な変化、潮流による生簀容積の減少がクロマグロの遊泳行動にどのような影響をもたらすのかを本研究で具体的に評価できるようになった。
  • クロマグロの遊泳能力の解明-バイオメカニクスとバイオテレメトリの統合研究-
    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 : 2006年 -2007年 
    代表者 : 高木 力, 河邊 玲, 光永 靖, 上野 公彦
     
    本研究ではバイオメカニクス(生体力学)研究を通して,クロマグロの遊泳能力と遊泳メカニズムそして本種の遊泳に対する形態機能を解明することを目的としている。3次元形態計測から本種のデジタル形態モデルを作製し,これを用いたCFD(数値流体力学)解析から本種の遊泳時流体力学的特性を明らかにした。成長に伴って魚体の抵抗係数は減少する傾向を示した。本種の遊泳時抵抗はおもに尾鰭の振動振幅の大きさに依存し,振動周波数はほとんど影響しないことがわかった。水平遊泳時の重心回りのモーメント推定から本種は低速遊泳時ではわずかに頭上げの姿勢で遊泳する必要があること,また,エネルギー効率を優先した遊泳では深い角度でグライドし,浅い角度で上昇する遊泳式が有利であることを理論で導いた。この推定結果は遊泳姿勢と尾鰭振動を記録する小型記録計で実海域計測されたフィールドデータによって裏付けられた。負の浮力である本種は自重を支持するために,胸鰭は揚力発生の重要な機能を果たしていると考えられていたが,CFD解析結果からも大きな揚力を発生できる器官であることが確認された。実際の個体で確認するため,磁力を用いて胸鰭の開度を記録する小型記録計を開発し,実海域実験を実施した。低速で遊泳するときには頻繁に胸鰭を大きく拡げ,揚力を獲得していることが明らかとなった。本種幼魚の遊泳時に計測される代謝エネルギーから遊泳時のエネルギー変換効率を見積もるため回流水槽を用いた生体実験を実施した。その結果,本種単位重量当たりの移動エネルギーコストに換算すると平均15000J/kg/kmであった。これに対し,CFDに基づいて,算出された遊泳に必要な仕事(エネルギー)は移動エネルギーコストの2-4%程度でしかなく,幼魚期では代謝エネルギーのほとんどが体温維持に使用されていることが示唆された。
  • クロマグロの遊泳能力と群行動メカニズムに関する研究
    研究期間 : 2003年 -2007年
  • 旋網漁具の網形状数値シミュレーションと最適操業システムの構築
    委託研究
    研究期間 : 2004年 -2006年
  • クロマグロ等魚類養殖施設の最適構造の検討
    研究期間 : 2003年 -2004年
  • 網漁具の形状と運動に関する数値シミュレーション手法の開発
    日本学術振興会:科学研究費助成事業 奨励研究(A)
    研究期間 : 2001年 -2002年 
    代表者 : 高木 力
     
    昨年度,網地の形状と運動を推定する数値計算用モデルを開発し試計算を行った。その結果,網形状は実測値と計算値で非常によく一致した。本年度は以下にあげる成果を得ることができた。 ■計算モデルに内在する問題点を把握するため,水槽実験により複数箇所の網糸に作用する荷重を測定し,計算値と比較した。その結果計算値はいずれの条件でも実測値よりも過小に推定された。この原因は網地に作用する抗力係数を一定として取り扱っていたことに起因していた。水槽実験時の網糸に対するレイノルズ数範囲ではCd値は流速の違いによって大きく変化する遷移域であった。そこでCd値をレイノルズ数の関数として与え,試計算したところ実測値と計算値は非常によく一致し,計算モデルの精度向上をはかることができた。 ■計算モデルは網地の結節部と脚部を質点としてこれらの運動方程式を連立して解いている。そのため大規模な網地では計算時間の増加は避けられない。そこで効率的な計算を行うため複数の目合をグループ化して計算質点数を減少させることを試みた。その結果10000質点の網地について4目をグループ化した場合,計算精度にほとんど影響を与えることはなく,計算時間は約1/8に減少させることができた。 ■算定結果の視覚化についてはグラフィックライブラリOpenGLを利用してより詳細かつ効率的に3次元表示が可能となった。これによって市販のグラフィクスアプリケーションソフトに依存することはなくなり,解析システムの開発がより柔軟に行えるようになった。 本研究で,網漁具形状をコンピュータによって推定する計算モデルを開発することができた。このモデルは定式化も容易なため応用性が高い。一連の研究成果から汎用性のある網地の形状・荷重を推定するシステムが実用化できる可能性は極めて高くなったといえる。今後は実際の網漁具に応用できるように最終的なシステムの完成を目指す。
  • 魚類遊泳時のアクアバイオメカニズムに関する研究
    研究期間 : 2002年
  • ヒラメ・カレイ類の遊泳滑空行動に関する流体力学的メカニズムの解明
    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 : 2000年 -2001年 
    代表者 : 梨本 勝昭, 高木 力, 平石 智徳, 内藤 靖彦
     
    本研究では津軽海峡沿岸域に生息するヒラメ成魚を対象に、活動の日周性と離底行動の機能および遊泳滑空の仕組みを明らかにした。 2000年10〜11月に10個体について加速度センサー搭載型データロガーをヒラメ成魚に装着して北海道知内町沖合に放流した。2個体の回収に成功して33.9時間、142.2時間にわたり遊泳速度、水深、水温、2軸の加速度の貴重な連続行動データを得ることができた。記録された加速度波形の明瞭な違いからヒラメの移動様式には次の2つのパターンがあることが明らかになった。 (1)Only-beat方式:離底開始から終了まで、遊泳に伴う加速度波形が連続的に記録される移動パターン。このパターンでは離底の高さは1mを超えることはまれであり、離底時間は3分間を超えることはない。 (2)Beat-glide方式:離底開始から終了までの時間、体の振動を継続させるパターン。このパターンでは上昇と下降を連続的に繰り返し、上昇時にのみ体を振動させて、下降時には滑空をする。離底の高さは1m以下になることはまれで、離底持続時間は最長で約24分間に及んだ。 二つの移動様式の間で解析した各パラメータについて比較したところ、遊泳持続時間には二つのパターン間に有意差が認められなかった。また水平移動距離はBeat-glide方式の方が有意に距離は長く、ヒラメは移動距離の長短に応じて移動方式を変えていることが示唆された。さらに、水平移動距離と魚体の振動数との間には、両パターンともに有意な正の相関が認められ、同じ距離を移動する場合にはBeat-glide方式ではOnly-beat方式に比べると振動回数を約22.3%節約でき、さらに酸素消費率で両者を比較すると62%の移動コスト軽減になることが試算され、ヒラメは移動離に応じて移動方式を選択していることが明らかとなった
  • 定置網内の魚群行動モデル
    研究期間 : 2001年
  • Numerical model of fish schooling behavior in a set net
  • Study on hydrodynamic characteristics of local water around oceanic life from the viewpoint of marine production
  • Study on net-avoidance of microplankton with quantitative sampling gear
  • Study on calculation of dynamic response of reticulate structure and evaluating its dynamics characteristics

教育活動情報

主要な担当授業

  • 水産工学特論Ⅰ
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 水産科学院
    キーワード : Fisheries engineering, Fishing technology, Applied math, Physics
  • 大学院共通授業科目(一般科目):自然科学・応用科学
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : Fisheries engineering, Fishing technology, Applied math, Physics
  • 環境と人間
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 食のバリューチェーン、Society 5.0、エネルギー、異分野融合、持続可能性、フィールド、ロバストネス(強靱性)
  • 海洋資源科学実験Ⅲ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 行動生態計測、衛星データ解析-マイクロ波リモートセンシング、海洋観測データ解析、魚類遊泳力学,魚類行動計測、水産海洋工学、数値流体解析
  • 水産科学英語Ⅰ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 科学英語論文,英文読解
  • 応用物理学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : ニュートン力学,常微分方程式の解法,流体の力学,流れの解析,数値計算法
  • 水産物理学入門
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 漁具?学,流体?学,材料?学,船舶?学,漁具漁法学

大学運営

委員歴

  • 2014年04月 - 現在   日本水産学会   シンポジウム企画委員会委員長
  • 2013年04月 - 現在   日本水産学会   編集委員
  • 2009年04月 - 現在   日本水産工学会   編集委員
  • 2007年04月 - 現在   エアロ・アクアバイオメカニズム学会   幹事
  • 2002年 - 現在   日本水産工学会   評議員
  • 2012年04月 - 2014年03月   日本水産学会   近畿支部幹事
  • 2012年04月 - 2013年10月   日本水産学会   水産教育推進委員
  • 2012年04月 - 2013年03月   日本水産学会   漁業懇話会委員長


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