Researcher Profile and Settings

Master

Affiliation (Master)

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

Affiliation (Master)

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

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Profile and Settings

Degree

• (BLANK)

Profile and Settings

• Name (Japanese)

  Takagi

• Name (Kana)

  Tsutomu

• Name

  200901073848104430

Achievement

Research Interests

• 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   

Research Areas

• Life sciences / Aquaculture
• Life sciences / Ecology and environmental science
• Aerospace, marine, and maritime Engineering / Marine and maritime engineering

Research Experience

• 2014/09 - Today Hokkaido University Faculty of Fisheries Sciences Prof.
• 1999/04 - 2014/08 Kinki University Faculty of Agriculture, Dapartment of Fish. Prof.
• 1997 - 1999 Marine Ecology and Environment Research Division, JAMSTEC
• 1996 - 1997 Special Researcher, Science and Technology Development Foundation
• 1995 - 1996 Posdoc researcher, Japan Society for the Promotion and Sciences
• 1991 - 1993 神奈川県水産試験場 技師

Education

•        - 1996  Hokkaido University
•        - 1996  Hokkaido University  Graduate School, Division of Fisheries
•        - 1991  Hokkaido University  School of Fisheries Sciences
•        - 1991  Hokkaido University  Faculty of Fisheries

Committee Memberships

• 2022/04 - Today   Society of Aero Aqua Bio-mechanisms   chairperson

Awards

• 2015/03 日本水産学会 水産学技術賞
   

  受賞者: 髙木 力
• 2006 the Third International Symposium on Aero Aqua Bio-Mechanisms Best Presentation Award
   Functional morphology of swimming bluefin tuna based on CFD analysis:I. Effects of morphology on hydrodynamic characteristics 

  受賞者: Yumiko Tamura;TAKAGI Tsutomu;Takeshi Yamane
• 2004 PICESベストポスタープレゼンテーション賞（共著）
  
• 2000 水産工学奨励賞(日本水産工学会)
  

Published Papers

• Estimating the Purse Seine Net Geometry during a Hauling Operation Using a Data Assimilation Method

  Shintaro Gomi, Tsutomu Takagi, Katsuya Suzuki, Tatsuki Oshima, Shoko Wada, Rika Shiraki, Yoshihiro Nishiyama, andIchiya Ogino

  Fishes 9 (10) 392  2024/09 [Refereed][Not invited]
  
• Adjustment of Parameters for Numerical Simulation of Fishing Net Dynamics Using a Data Assimilation Method

  Shintaro Gomi, Tsutomu Takagi, Katsuya Suzuki, Tatsuki Oshima, Shoko Wada, Rika Shiraki, Ichiya Ogino, Shigeru Asaumi

  International Journal of Offshore and Polar Engineering 34 (3) 299 - 305 1053-5381 2024/09/01
• Drafting behaviors in fish induced by a local pressure drop around a hydrofoil model

  Go Eguchi, Tsutomu Takagi, Shinsuke Torisawa, Kohsei Takehara

  Journal of Theoretical Biology 588 111821 - 111821 0022-5193 2024/07
• Fish balances flow resistance and high pressure in stagnation area (in press)

  Go Eguchi, Shinsuke Torisawa, Kohsei Takehara, Tsutomu Takagi

  Journal of Aero Aqua Bio-mechanisms 2023/06 [Refereed][Not invited]
  
• Hydrodynamics of the sea cucumber <i>Apostichopus japonicus</i> in flow and acceleration fields

  Yuto Tanaka, Yuichi Sakai, Go Eguchi, Tsutomu Takagi

  Journal of Aero Aqua Bio-mechanisms 10 (1) 24 - 32 2023
• New technologies to improve bycatch mitigation in industrial tuna fisheries

  Francois Poisson, Pierre Budan, Sylvain Coudray, Eric Gilman, Takahito Kojima, Michael Musyl, Tsutomu Takagi

  FISH AND FISHERIES 1467-2960 2021/12 [Refereed]
   

  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.
• Development of fish spatio-temporal identifying technology using SegNet in aquaculture net cages

  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 0144-8609 2021/05 [Refereed]
  
• Hydrodynamical effect of parallelly swimming fish using computational fluid dynamics method

  Keisuke Doi, Tsutomu Takagi, Yasushi Mitsunaga, Shinsuke Torisawa

  PLOS ONE 16 (5) 1932-6203 2021/05 [Refereed]
   

  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.
• Controlling a Fishing Net Geometry Underwater Using a Data Assimilation Method

  Shintaro Gomi, Tsutomu Takagi, Katsuya Suzuki, Rika Shiraki, Ichiya Ogino, Shigeru Asaumi

  APPLIED OCEAN RESEARCH 106 0141-1187 2021/01 [Refereed]
   

  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.
• Analysis of sinking death using video images of the swimming performance of Pacific Bluefin tuna (Thunnus orientalis) larvae

  Y. Ina, T. Takagi, S. Miyashita, M. Kurata, T. Honryo, Y. Sawada, H. Fukuda, S. Torisawa

  Aquacultural Engineering 90 102099 - 102099 0144-8609 2020/08 [Refereed]
  
• Mechanical efficiency of fish thrust induced by tail beating: comparison between kinetic energy and metabolic energy

  Eguchi Go, Aoki Yuki, Torisawa Shinsuke, Takehara Kohsei, Takagi Tsutomu

  Journal of Aero Aqua Bio-mechanisms 8 (1) 54 - 62 2019 [Not refereed]
   

  There are few studies that compare thrust power P_T induced by tail beating with net metabolic power P_net obtained from oxygen consumption and mechanical efficiency η (= P_T P_net ^-1) of fish thrust. In this study, P_T and P_net were obtained using two species of chub mackerel and Japanese dace, and η was calculated by comparing kinetic energy and metabolic energy. P_T was calculated by multiplying swimming speed V_swim and thrust force T obtained using two calculation methods, the Milne-Thomson principle and Kutta-Joukowski theorem. Comparing each value, η showed a certain ratio irrespective of fish species and swimming speed. Linear approximation resulted in P_T = 0.21 P_net for Milne-Thomson and P_T = 0.44 P_net for Kutta-Joukowski.
• Performance of a multi-stereovision technique to enhance the accuracy of fish body measurement for aquaculture management

  Tatsuya Tanaka, Kazuyoshi Komeyama, Shinsuke Torisawa, Takeharu Yamaguchi, Shigeru Asaumi, Tsutomu Takagi

  NIPPON SUISAN GAKKAISHI 85 (3) 314 - 320 0021-5392 2019 [Refereed]
   

  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 2018/07 [Refereed][Not invited]
  
• Development of Non-contact Measure Ring System for Aquaculture Using Image Analysis

  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 日本水産工学会 54 (3) 209 - 213 0916-7617 2018/02 [Not refereed][Invited]
  
• Particle filter for automated measurement of chub mackerel trajectory using stereo vision

  Makoto Sakamoto, Kazuyoshi Komeyama, Osamu Tamaru, Shinsuke Torisawa, Tsutomu Takagi

  NIPPON SUISAN GAKKAISHI 84 (5) 787 - 795 0021-5392 2018 [Refereed]
   

  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.
• Body Measurement of Reared Red Sea Bream Using Stereo Vision.

  Kazuyoshi Komeyama, Tatsuya Tanaka, Takeharu Yamaguchi, Shigeru Asaumi, Shinsuke Torisawa, Tsutomu Takagi

  Journal of Robotics and Mechatronics 30 (2) 231 - 237 0915-3942 2018 [Refereed][Not invited]
   

  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 2017/10 [Refereed][Not invited]
  
• 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 2017/10 [Refereed][Not invited]
  
• Current situation and future issues of implementation of ICT in fisheries industry

  Tsutomu Takagi, Shigeru Asaumi, Shinsuke Torisawa, Masahiko Ariji

  NIPPON SUISAN GAKKAISHI 83 (1) 91 - 91 0021-5392 2017 [Not refereed][Not invited]
  
• Development of support systems for fishing technology: introduction of ICT in purse seine fishing

  Tsutomu Takagi

  NIPPON SUISAN GAKKAISHI 83 (1) 92 - 92 0021-5392 2017 [Refereed][Not invited]
  
• How Many Fish in a Tank? Constructing an Automated Fish Counting System by Using PTV Analysis

  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 0277-786X 2017 [Refereed][Not invited]
   

  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.
• State-space model for estimating three-dimensional fish trajectories based on acoustic telemetry in large tank

  Kazuyoshi Komeyama, Minoru Kadota, Hiroyuki Sueshige, Kazuhiko Anraku, Tsutomu Takagi

  Fisheries Engineering 日本水産工学会 53 (1) 1 - 13 0916-7617 2016/07 [Refereed][Not invited]
   

  Three-dimensional fish trajectories were analysed based on acoustic telemetry collected using a large experimental tank （600 m3）and refined with a state-space model to which the Kalman filter was applied. The movements of three red sea bream fitted with acoustic transmitters （at 63, 75, and 84 kHz）were monitored simultaneously using four hydrophones. On the basis of the differences in the times at which the transmitted sound signals arrived at each hydrophone, the positions of the fish were determined as the intersections of hyperboloid functions. A performance test of this system showed that it can be used to detect transmitter positions in a three-dimensional coordinate system with mean accuracy and precision of 0.69 m and 0.02‒0.04 m, respectively, with the 63 kHz transmitter, which generated the best results. The accuracy and precision were better for horizontal measurements than for vertical measurements, and the precision degraded with increasing transmitter frequency. These results indicate that it is possible to improve the precision of the system by employing a sampling rate that is sufficientin relation to the transmitter frequency. Because of the significant error in the measurements, the swimming trajectories were refined using estimates obtained from a state-space model and the Kalman filter. For three of the fish, the estimated horizontal trajectories remained within the boundaries representing the walls of the tank. This study demonstrates that applying a state-space model to acoustic telemetry with large error can produce results that closely approximate the actual swimming trajectories of fish.
• Towards an Approach to 6 DOF Inertial Kinematics

  Holger Korte, Jan-Hendrik Wesuls, Sven Stuppe, Tsutomu Takagi

  IFAC PAPERSONLINE 49 (23) 440 - 445 2405-8963 2016 [Refereed][Not invited]
   

  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.
• Energy-Saving in Schooling Japanese Mackerel Scomber joponicus and the effect of induced velocity of wake vortices.

  Tsutomu Takagi, Shizuka Ito, Shinsuke Torisawa, Yoshinobu Inada

  Journal of Aero Aqua Bio-mechanisms Society of Aero Aqua Bio-mechanisms 4 (1) 78 - 82 2185-1522 2015/06 [Refereed][Not invited]
   

  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.
• A method for measuring the swimming behaviour of pacific bluefin tuna

  Kazuyoshi Komeyama, Tsutomu Takagi

  Biology and Ecology of Bluefin Tuna 400 - 417 2015/01/01 

  Knowledge about the underwater behaviour of fish remains limited because technology sensitive enough to elucidate detailed behaviour (and behavioural transitions) through indirect observation has yet to be developed. Although techniques that can be used to track fish positions underwater have been introduced, deficiencies remain that require improvement.
• Schooling behavior of Pacific bluefin tuna

  Hiromu Fukuda, Shinsuke Torisawa, Tsutomu Takagi

  Biology and Ecology of Bluefin Tuna 292 - 308 2015/01/01 

  “The tunny proper, the pelamys, and the bonito penetrate into the Euxine in summer and pass the summer there as do also the greater part of such fish as swim in shoals with the currents, or congregate in shoals together. And most fish congregate in shoals, and shoal-fishes in all cases have leaders”.
• Visual physiology

  Shinsuke Torisawa, Hiromu Fukuda, Tsutomu Takagi

  Biology and Ecology of Bluefin Tuna 309 - 324 2015/01/01 

  Vision is an important sensory system for most fish species. Fish eyes are similar to the eyes of terrestrial vertebrates such as birds and mammals, except that they have highly spherical lens. The retinas generally have both rod and cone cells (for scotopic and photopic vision, respectively), and most species have colour vision. Unlike humans, fish normally adjust their focus by moving the lens closer to, or further from, the retina.
• Ontogeny of swim bladder inflation and caudal fin aspect ratio with reference to vertical distribution in Pacific bluefin tuna Thunnus orientalis larvae

  Yoshiaki Ina, Wataru Sakamoto, Shigeru Miyashita, Hiromu Fukuda, Shinsuke Torisawa, Tsutomu Takagi

  FISHERIES SCIENCE 80 (6) 1293 - 1299 0919-9268 2014/11 [Refereed][Not invited]
   

  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.
• Effect of mesh size on sinking characteristics of purse seine net: a parametric study by numerical simulation.

  TAKAGI Tsutomu

  Fisheries Engineering 日本水産工学会 51 (1) 11 - 19 0916-7617 2014/07 [Refereed][Not invited]
   

  We numerically modeled the geometry of a purse seine net and evaluated the model's dynamic behavior during operation. The vessel position, wire payout and roll-up lengths, and current flow speed and direction in situ were collected as the dataset for computation. The mesh sizes of the upper, middle, and lower sections of the main net were changed to double and half their respective sizes, and the sinking speed and depth were compared among nets of different mesh sizes. The net with doubled mesh size in the lower section and constant mesh bar diameter strongly affected the sinking speed and depth. This implies that a large mesh size in the lower part of the main net, which eliminates the need for providing a thicker mesh bar, should be used for enhancing the efficiency of fishing operations.
• Ontogenetic changes in schooling behavior and visual sensitivity during larval and juvenile stages in Pacific bluefin tuna, Thunnus orientalis

  Hiromu Fukuda, Shinsuke Torisawa, Tsutomu Takagi

  BULLETIN OF FISHERIES RESEARCH AGENCY (38) 135 - 139 1346-9894 2014/03 [Refereed][Not invited]
   

  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 2014/02 [Not refereed][Not invited]
  
• Hydrodynamics and energy-saving swimming techniques of Pacific bluefin tuna

  Tsutomu Takagi, Yumiko Tamura, Daniel Weihs

  Journal of Theoretical Biology 336 158 - 172 0022-5193 2013/11/07 [Refereed][Not invited]
   

  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 2013/10 [Refereed][Not invited]
  
• Dynamic modeling for fishing gear and its numerical simulation

  Tsutomu Takagi

  NIPPON SUISAN GAKKAISHI 79 (5) 778 - 781 0021-5392 2013/09 [Not refereed][Not invited]
  
• Three-dimensional trajectories of cultivated Pacific bluefin tuna Thunnus orientalis in an aquaculture net cage.

  Kazuyoshi Komeyama, Minoru Kadota, Shinsuke Torisawa, Tsutomu Takagi

  Aquaculture Environment Interactions 4 (1) 81 - 90 1869-215X 2013/06 [Refereed][Not invited]
   

  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 2013/05 [Refereed][Not invited]
  
• アーカイバルタグを用いた幼魚期における養殖クロマグロの異常行動検出の試み

  米山 和良, 近藤 了太郎, 藤岡 紘, 門田 実, 安樂 和彦, 鳥澤 眞介, 高木 力

  日本水産工学会 学術講演会 学術講演論文集 日本水産工学会 2013 59 - 62 0917-3943 2013
• II-1. Computational modeling of fishing net

  Tsutomu Takagi

  Nippon Suisan Gakkaishi (Japanese Edition) 78 (5) 1018  1349-998X 2012 [Not refereed][Not invited]
  
• Constructing a mathematical model of fishery system, and estimating ideal aquaculture and catch-fishery products.

  Minoru Kadota, Shinsuke Torisawa, Takeshi Yamane, Tsutomu Takagi

  Fisheries Engineering 日本水産工学会 48 (3) 197 - 203 0916-7617 2012 [Refereed][Not invited]
   

  The balance between capture fishery and aquaculture production is extremely important for maintaining and developing the fishery industry. In this study, we addressed the problem of optimizing aquaculture and capture fisheries production from the viewpoint of effectively using finite aquatic resources. Our goal was to maximize total fishery production by controlling the ratio of aquaculture to capture fishery production. A simple mathematical model was constructed to describe total fishery production as the sum of capture fishery production and aquaculture production. This model did not consider any economic aspects, but simply focused on the production flow. Aquaculture and capture fishery production interacted in the model via the parameter α, which was defined as the ratio of capture fishery production that turned into aquaculture bait. It was assumed that there was a bounded exponential curve relationship between the amount of bait used in aquaculture and aquaculture production. It was also assumed that aquaculture production was not used for bait in aquaculture or capture fishery. Within this framework, total production was critically dependent on the parameter α. We also analyzed the FAO data (nonfood uses, aquaculture, and capture production data were used). The results indicated that total fishery production was maximized if the amount of the bait used in aquaculture is limited to about 15% of capture fishery production. Sensitivity analysis also indicated that the upper bound of α should be maintained at less than 18.9% to maximize total fishery production.
• A method of three-dimensional monitoring of free-swimming Pacific bluefin tuna, Thunnus orientalis, cultured in a net cage using a digital stereo-video camera system.

  Shinsuke Torisawa, Minoru Kadota, Kazuyoshi Komeyama, Tsutomu Takagi

  Fisheries Engineering 日本水産工学会 49 (1) 13 - 20 0916-7617 2012 [Refereed][Not invited]
   

  A digital stereo-camera system was used for 3-dimensional monitoring of cultured Pacific blufin tuna Thunnus orientalis individuals, which were free-swimming in a net cage. The fork lengths and the length frequency distribution of tuna individuals in a net cage were estimated using the Direct Linear Transformation (DLT) method. Information obtained from stereo-images is useful for managing the growth of tuna during rearing. In this research, we are trying to develop the simple method involving a combination of DLT and a commercial image processing software to enable aquaculturists to obtain three-dimensional measurements of fish. Then, we used a digital 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 <9.2m from the camera system, estimates for 100% (37/37) were found to be valid, with an error ratio (standard error/mean) of 5%. Therefore, we believed that our proposed simple non-destructive method for monitoring free-swimming fish could be very useful for aquaculture management.
• Employing relative entropy techniques for assessing modifications in animal behavior

  Minoru Kadota, Eric J. White, Shinsuke Torisawa, Kazuyoshi Komeyama, Tsutomu Takagi

  PLoS ONE 6 (12) e28241  1932-6203 2011/12/02 [Refereed][Not invited]
   

  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.
• Analysis of juvenile tuna movements as correlated random walk

  Minoru Kadota, Shinsuke Torisawa, Tsutomu Takagi, Kazuyoshi Komeyama

  Fisheries Science 77 (6) 993 - 998 0919-9268 2011/11 [Refereed][Not invited]
   

  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.
• Schooling behaviour of juvenile Pacific bluefin tuna Thunnus orientalis depends on their vision development

  S. Torisawa, H. Fukuda, K. Suzuki, T. Takagi

  Journal of Fish Biology 79 (5) 1291 - 1303 0022-1112 2011/11 [Refereed][Not invited]
   

  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.
• Seasonal distribution of adult crucian carp nigorobuna Carassius auratus grandoculis and gengoroubuna Carassius cuvieri in Lake Biwa, Japan

  Yoshio Kunimune, Yasushi Mitsunaga, Kazuyoshi Komeyama, Masanari Matsuda, Toru Kobayashi, Tsutomu Takagi, Takeshi Yamane

  Fisheries Science 77 (4) 521 - 532 0919-9268 2011/07 [Refereed][Not invited]
   

  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.
• Ontogenetic changes in behaviour transmission among individuals in the schooling of Pacific bluefin tuna Thunnus orientalis

  Hiromu Fukuda, Yoshifumi Sawada, Tsutomu Takagi

  AQUATIC LIVING RESOURCES 24 (2) 113 - 119 0990-7440 2011/04 [Refereed][Not invited]
   

  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.
• A digital stereo-video camera system for three-dimensional monitoring of free-swimming Pacific bluefin tuna, Thunnus orientalis, cultured in a net cage

  Shinsuke Torisawa, Minoru Kadota, Kazuyoshi Komeyama, Katsuya Suzuki, Tsutomu Takagi

  Aquatic Living Resources 24 (2) 107 - 112 0990-7440 2011/04 [Refereed][Not invited]
   

  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.
• Measuring the swimming behaviour of a reared Pacific bluefin tuna in a submerged aquaculture net cage

  Kazuyoshi Komeyama, Minoru Kadota, Shinsuke Torisawa, Katsuya Suzuki, Yuichi Tsuda, Tsutomu Takagi

  Aquatic Living Resources 24 (2) 99 - 105 0990-7440 2011/04 [Refereed][Not invited]
   

  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.
• Concernment of rheotactic reaction and schooling behaviour traits of the dwarf sweetfish, Plecoglossus altivelis on a capture process of the set-net “eri”.

  FUKUDA Hiromu, TORISAWA Shinsuke, YAMANE Takeshi, TAKAGI Tsutomu

  Fisheries Engineering 日本水産工学会 48 (2) 117 - 124 0916-7617 2011 [Refereed][Not invited]
   

  We investigated schooling behaviour and the rheotactic reaction in the dwarf sweetfish Plecoglossus altivelis. Under 400lx illumination, the fish formed schools with low polarity; these aggregations were highly compact. There was no schooling behaviour in darkness (0.01lx). A positive rheotactic reaction occurred at current velocities >3.3cm s^<-1>. At current speeds ≥5.2cm s^<-1>, fish ground speeds declined to zero. There was no clear rheotaxis at current speeds <3.3cm s^<-1>. These results suggested that the stimuli by these slow currents might be too weak to increase the rheotaxis of P. altivelis. Current speed was thus an important factor affecting swimming effort and direction in P. altivelis. Current effects may be particularly strong in dwarf sweetfish because the schools have low polarity.
• Developmental changes in behavioral and retinomotor responses of Pacific bluefin tuna on exposure to sudden changes in illumination

  Hiromu Fukuda, Shinsuke Torisawa, Yoshifumi Sawada, Tsutomu Takagi

  AQUACULTURE 305 (1-4) 73 - 78 0044-8486 2010/07 [Refereed][Not invited]
   

  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.
• Ontogenetic changes in schooling behaviour during larval and early juvenile stages of Pacific bluefin tuna Thunnus orientalis

  H. Fukuda, S. Torisawa, Y. Sawada, T. Takagi

  JOURNAL OF FISH BIOLOGY 76 (7) 1841 - 1847 0022-1112 2010/05 [Refereed][Not invited]
   

  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
• Functional morphology of the flounder allows stable and efficient gliding: an integrated analysis of swimming behaviour

  Tsutomu Takagi, Ryo Kawabe, Hiroyuki Yoshino, Yasuhiko Naito

  AQUATIC BIOLOGY 9 (2) 149 - 153 1864-7790 2010 [Refereed][Not invited]
   

  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.
• Morphological features and functions of bluefin tuna change with growth

  Yumiko Tamura, Tsutomu Takagi

  FISHERIES SCIENCE 75 (3) 567 - 575 0919-9268 2009/05 [Refereed][Not invited]
   

  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.
• 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  2009/03 [Not refereed][Not invited]
  
• 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  2009/03 [Not refereed][Not invited]
  
• 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 日本水産学会大会春季大会 13  2009/03 [Not refereed][Not invited]
  
• 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  2009/03 [Not refereed][Not invited]
  
• 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 日本水産学会大会春季大会 13  2009/03 [Not refereed][Not invited]
  
• High-frequency depth recording reveals the vertical movement of flounder in the Tsugaru Strait of northern Japan

  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 1023-6244 2009 [Refereed][Not invited]
   

  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.
• Numerical analysis of net cage dynamic behavior due to concurrent waves and current

  Katsuya Suzuki, Shinsuke Torisawa, Tsutomu Takagi

  Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE 4 1513 - 1520 2009 [Refereed][Not invited]
   

  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.
• Analysis of fish movement using a genetic algorithm: factors influencing the occurrence of fish near a set-net

  K. Komeyama, K. Suzuki, T. Takagi, Y. Mitsunaga, T. Yamane, T. Hiraishi

  FISHERIES MANAGEMENT AND ECOLOGY 15 (5-6) 347 - 355 0969-997X 2008/10 [Refereed][Not invited]
   

  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 日本水産学会大会春季大会 173  2008/03 [Not refereed][Not invited]
  
• Numerical analysis of dynamic behavior of Danish seining and sea trial verification,

  SUZUKI K.

  Mathematical and Physical Fisheries Science 6 (6) 11 - 22 2008 [Not refereed][Not invited]
  
• Dynamics of boat seine fishing using a net geometry simulator

  Katsuya Suzuki, Tsutomu Takagi

  Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE 3 865 - 870 2008 [Refereed][Not invited]
   

  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.
• Evaluating the impact of gillnet ghost fishing using a computational analysis of the geometry of fishing gear

  Tsutomu Takagi, Takashi Shimizu, Holger Korte

  ICES JOURNAL OF MARINE SCIENCE 64 (8) 1517 - 1524 1054-3139 2007/11 [Refereed][Not invited]
   

  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 2007/11 [Refereed][Not invited]
  
• Changes in the retinal cone density distribution and the retinal resolution during growth of juvenile Pacific bluefin tuna Thunnus orientalis

  Shinsuke Torisawa, Tsutomu Takagi, Yasunori Ishibashi, Yoshifumi Sawada, Takeshi Yamane

  FISHERIES SCIENCE 73 (5) 1202 - 1204 0919-9268 2007/10 [Refereed][Not invited]
  
• Schooling behaviour and retinomotor response of juvenile Pacific bluefin tuna Thunnus otientalis under different light intensities

  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 0022-1112 2007/08 [Refereed][Not invited]
   

  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.
• Application of NaLA, a fishing net configuration and loading analysis system, to bottom gill nets

  Takashi Shimizu, Tsutomu Takagi, Holger Korte, Tomonori Hiraishi, Katsutaro Yamamoto

  FISHERIES SCIENCE 73 (3) 489 - 499 0919-9268 2007/06 [Refereed][Not invited]
   

  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.
• Using a netting geometry simulator to develop smart fishing and smart gear

  Tsutomu Takagi, Takashi Shimizu, Holger Korte, Katsuya Suzuki

  Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE 5 45 - 52 2007 [Refereed][Not invited]
   

  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.
• Mathematical and experimental analysis of schooling behavior during growth in juvenile chub mackerel: Considerations of population density and space limitation

  Katsuya Suzuki, Shinsuke Torisawa, Tsutomu Takagi

  Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE 5 69 - 75 2007 [Refereed][Not invited]
   

  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 [Not refereed][Not invited]
  
• 数値シミュレーションを用いた障害物に対する魚群の回避行動の定量的評価

  鈴木 勝也, 髙木 力, 宮下 和士

  数理水産科学 数理水産科学研究会 4 23 - 28 1348-6802 2006 [Not refereed][Not invited]
  
• 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 [Not refereed][Not invited]
  
• Application of NaLA, a fishing net configuration and loading analysis system, to drift gill nets

  T. Takagi, Shimizu Takashi, Holger Korte, Hiraishi Tomonori, Yamamoto Katsutaro

  FISHERIES RESEARCH 76 (1) 67 - 80 0165-7836 2005/10 [Refereed][Not invited]
   

  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 2005/10 [Refereed][Not invited]
  
• 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 2005/10 [Refereed][Not invited]
  
• ﾊﾞｲｵﾛｷﾞﾝｸﾞ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  2005/02 [Not refereed][Not invited]
   

  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
• 魚群行動における視覚と側線感覚機能の数理モデルによる評価

  鈴木 勝也, 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 数理水産科学研究会 3 15 - 20 1348-6802 2005 [Not refereed][Not invited]
  
• 明暗によるチカ Hypomesus japonicus 魚群の遊泳行動の変化

  鈴木 勝也, 高木 力, 宮下 和士

  日本水産工学会学術講演会講演論文集 16 195 - 196 0917-3943 2004 [Not refereed][Not invited]
  
• 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 [Not refereed][Not invited]
  
• Validity and visualization of a numerical model used to determine dynamic configurations of fishing nets

  K Suzuki, T Takagi, T Shimizu, T Hiraishi, K Yamamoto, K Nashimoto

  FISHERIES SCIENCE 69 (4) 695 - 705 0919-9268 2003/08 [Refereed][Not invited]
   

  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 2003/05 [Not refereed][Not invited]
  
• Performance of “NaLA”: a fishing net shape simulator

  TAKAGI T

  Fisheries engineering 日本水産工学会 40 (2) 125 - 134 0916-7617 2003 [Refereed][Not invited]
   

  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 [Not refereed][Not invited]
  
• Development of the numerical simulation method of dynamic fishing net shape

  T Takagi, K Suzuki, T Hiraishi

  NIPPON SUISAN GAKKAISHI 68 (3) 320 - 326 0021-5392 2002/05 [Refereed][Not invited]
   

  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.
• Modeling of net for calculation method of dynamic fishing net shape

  Tsutomu Takagi, Katsuya Suzuki, Tomonori Hiraishi

  Fisheries Science 68 (sup2) 1857 - 1860 1444-2906 2002 [Refereed][Not invited]
   

  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 2001/11 [Refereed][Not invited]
  
• 成長ステージと個体数の違いによるマサバ魚群の遊泳行動の変化

  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 0917-3943 2001 [Not refereed][Not invited]
  
• Computer Simulation for Netting Gear Design (Hydrodynamic Aspects of Fishing Gears : II. Practical Researches)

  TAKAGI Tsutomu, Tsutomu Takagi, Faculty of Agriculture Kinki University

  NSUGAF The Japanese Society of Fisheries Science 66 (5) 901 - 902 0021-5392 2000/09/15
• 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 [Not refereed][Not invited]
  
• Wave Loads and Responses of Fishing Gears (Hydrodynamic Aspects of Fishing Gears : I Basic Researches)

  TAKAGI Tsutomu, Tsutomu Takagi, Faculty of Agriculture Kinki University

  NSUGAF The Japanese Society of Fisheries Science 65 (5) 925 - 926 0021-5392 1999/09/15
• SELECTIVITY OF TRAPS FOR WHELKS NEPTUNEA-ARTHRITICA

  K NASHIMOTO, K SUZUKI, T TAKAGI, K MOTOMATSU, T HIRAISHI

  NIPPON SUISAN GAKKAISHI 61 (4) 525 - 530 0021-5392 1995/07 [Refereed][Not invited]
   

  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.
• FISH SCHOOLING BEHAVIOR IN WATER TANKS OF DIFFERENT SHAPES AND SIZES

  T TAKAGI, K NASHIMOTO, K YAMAMOTO, T HIRAISHI

  NIPPON SUISAN GAKKAISHI 59 (8) 1279 - 1287 0021-5392 1993/08 [Refereed][Not invited]
   

  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.

MISC

• Exploiting High-Speed Imaging to Understand Fish Swimming Mechanisms

  高木力, 江口剛, 田中優斗, 竹原幸生, 鳥澤眞介  高速度イメージングとフォトニクスに関する総合シンポジウム講演論文集(CD-ROM)  2023-  2023
• 魚群を構成する個体の計数技術の開発―個体画像抽出手法の検討―

  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  2019/03/26  [Not refereed][Not invited]
  
• 魚類の遊泳時波状運動による体側面圧力分布と推進効率

  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  2018/09/15  [Not refereed][Not invited]
  
• 東シナ海及び台湾周辺海域におけるカンパチの回遊生態 I 台湾周辺海域における水平および鉛直遊泳行動

  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  2018/03/26  [Not refereed][Not invited]
  
• 画像解析を用いた非接触型養殖魚計測システムの開発

  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  2017/05/27  [Not refereed][Not invited]
  
• 遊泳する魚群の個体数計測システムの開発―個体画像抽出手法の違いが計数精度に与える影響―

  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  2017/03/26  [Not refereed][Not invited]
  
• 遊泳する魚群の個体数計測システムの開発―PTV解析技術を用いた新たな試み―

  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  2016/03/26  [Not refereed][Not invited]
  
• クロマグロ沖合養殖施設の研究開発’12-II 情報量を用いた養殖クロマグロの行動評価

  米山和良, 門田実, 鳥澤眞介, 森本真人, 高木力, 藤岡紘, 近藤了太郎, 安樂和彦, 浅海茂, 小林次彦  日本水産学会大会講演要旨集  2013-  2013
• Aiming at Smart Fishery in the 21^ century

  FUWA SHIGERU, HU FUXIANG, TAKAGI TSUTOMU, YAMANE TAKESHI  日本水産學會誌 = Bulletin of the Japanese Society of Scientific Fisheries  78-  (5)  1013  -1013  2012/09/15
• 養殖クロマグロ幼魚の特異行動の検出

  米山和良, 門田実, 藤岡紘, 安樂和彦, 近藤了太郎, 田中一成, 谷和博, 鳥澤眞介, 高木力  日本水産学会大会講演要旨集  2012-  2012
• Analysis of juvenile tuna movements as correlated random walk (vol 77, pg 993, 2011)

  Minoru Kadota, Shinsuke Torisawa, Tsutomu Takagi, Kazuyoshi Komeyama, Hiromu Fukuda  FISHERIES SCIENCE  78-  (1)  207  -207  2012/01  [Not refereed][Not invited]
  
• Application of NaLA: From Study to Practical Use.

  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  [Not refereed][Not invited]
  
• 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  [Not refereed][Not invited]
  
• 模型実験による浮沈式生簀の挙動解析 : 余剰浮力のアンバランスによる生簀の姿勢変化

  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  2010/05/22
• 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  [Not refereed][Not invited]
  
• 遺伝的アルゴリズムを用いたコイの行動に影響を与える環境要因の解析

  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  2008/03/27  [Not refereed][Not invited]
  
• 遺伝的アルゴリズムを用いた定置網漁場への魚の来遊に影響を与える環境要因の推定

  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  2007/03/28  [Not refereed][Not invited]
  
• アユの流れに対する応答特性

  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  2006/06/10
• バイオロギングとバイオメカニクスの統合研究によるヒラメのtailbeat-and-glide行動の解析

  Kawabe R, Takagi T  Bulletin of the Japanese Society of Fisheries Oceanography  70-  (2)  132  -249  2006/05  [Not refereed][Not invited]
  
• CFD Analysis for Fluid Dynamics of Bluefin Tuna

  Tamura Yumiko, Takagi Tsutomu  Memoirs of the Faculty of Agriculture of Kinki University  39-  75  -77  2006/03/31  

  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 forces 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.
• Quantitative analysis of schooling behaviour and retinal adaptation in juvenile pacific bluefin tuna under different light intensities (第6回数理水産科学研究交流会特集号)

  鳥澤 眞介, Takagi Tsutomu, Fukuda Hiromu  数理水産科学  4-  2  -10  2006
• 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  [Not refereed][Not invited]
  
• CFDによる人工魚礁周りの流れ解析

  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  2005/05/28
• 網地形状シミュレータNaLAのまき網への適用

  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  2005/05/28
• 刺網における漁獲プロセスの物理モデル (第5回数理水産科学研究交流会特集号)

  清水 孝士, 高木 力, 平石 智徳  数理水産科学  3-  86  -91  2005
• Application of NaLA, a Fishing Net Configuration and Loading Analysis System, to tuna net-cage (Special Issue: Proceedings of the 21st Century COE International Symposium on Stock Enhancement and Aquaculture Technology) -- (Poster session)

  Shimizu Takashi, Takagi Tsutomu, Korte Holger  Memoirs of the Faculty of Agriculture of Kinki University  (38)  173  -177  2005
• 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  [Not refereed][Not invited]
  
• Mathematical model of fish schooling behaviour in a set-net

  T Takagi, Y Moritomi, J Iwata, H Nakamine, N Sannomiya  ICES JOURNAL OF MARINE SCIENCE  61-  (7)  1214  -1223  2004/10  [Not refereed][Not invited]
   

  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.
• Refined calculation model for NaLA, a fishing net shape simulator, applicable to gill nets

  T Shimizu, T Takagi, K Suzuki, T Hiraishi, K Yamamoto  FISHERIES SCIENCE  70-  (3)  401  -411  2004/06  [Not refereed][Not invited]
   

  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.
• 網地形状シミュレータNaLAを用いた垂下式ホタテ養殖籠の運動推定

  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  2004/05/29
• 定置網周辺の流動環境と漁獲との関係 : CFDによる流れ構造解析

  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  2004/05/29
• 負の浮力の魚の遊泳移動に関する力学的解析 (第4回数理水産科学研究交流会特集号)

  高木 力, 田村 優美子, 河邊 玲  数理水産科学  2-  43  -50  2004
• 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  [Not refereed][Not invited]
  
• Validity and layout of "NaLA": A net configuration and loading analysis system

  Tsutomu Takagi, Takashi Shimizu, Katsuya Suzuki, Tomonori Hiraishi, Katsutaro Yamamoto  Fisheries Research  66-  (2-3)  235  -243  2004  [Not refereed][Not invited]
   

  We have developed a system for determining fishing net configuration and for loading analysis, called NaLA, which uses 3D dynamic visualization it is available for general and practical use with computer-aided design systems. This paper examines the validity of the numerical model employed in NaLA by using flume tank tests, and the model is then refined by modifying the drag parameters to improve the accuracy of estimates. There is close agreement between experimental and theoretical values for net shape configuration, and experimental values for tension loads agree well with calculated results when the drag coefficients are treated as a function of the Reynolds number. Our numerical method, in which four adjacent meshes are grouped into one large mesh, is effective in reducing computational effort. © 2003 Elsevier B.V. All rights reserved.
• Numerical Simulation Technology for Fishing Gear Engineering and its Potentiality

  TAKAGI Tsutomu, SHIMIZU Takashi, SUZUKI Katsuya  Journal of Fisheries Engineering  41(1),53-58-  (1)  53  -59  2004  [Not refereed][Not invited]
   

  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.
• Validity and visualization of a numerical model used to determine dynamic configurations of fishing nets (vol 69, pg 695, 2003)

  K Suzuki, T Takagi, T Shimizu, T Hiraishi, K Yamamoto, K Nashimoto  FISHERIES SCIENCE  69-  (5)  1084  -1084  2003/10  [Not refereed][Not invited]
  
• 水産学におけるCFD解析の応用 (第3回数理水産科学研究交流会特集号)

  高木 力, 吉野 博之, 河邊 玲  数理水産科学  1-  77  -80  2003
• 網地形状シミュレータ"NaLA"刺網モデルの確立--現状と今後の発展 (第3回数理水産科学研究交流会特集号)

  清水 孝士, 高木 力, 鈴木 勝也  数理水産科学  1-  121  -125  2003
• Video analysis of fish schooling behavior in finite space using a mathematical model

  K Suzuki, T Takagi, T Hiraishi  FISHERIES RESEARCH  60-  (1)  3  -10  2003/01  [Not refereed][Not invited]
   

  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.
• 網地形状シミュレータNaLAの計算モデル最適化

  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  2002/05/24
• Contributions on the theory of fishing gears and related, Marine systems

  2-  2002  [Not refereed][Not invited]
  
• 数値計算による網地形状の推定と最適なモデル化の検討

  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  2001/05/31
• デジタルビデオカメラによるオオクチバスの遊泳行動解析

  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  2001/04/01  [Not refereed][Not invited]
  
• Studies on Three-Dimensional Wave Deformations around Wave Control Structure for Developing Fishing Grounds

  TAKAGI Tsutomu  Fisheries engineering  37-  (2)  99  -105  2000/12/01
• 波動場中に並列に設置した柱状浮体の流体力学的特性

  木下 智夫, 高木 力  日本水産工学会学術講演会講演論文集  12-  151  -152  2000/06/08
• ウニの逃避防止用のエアポケットフェンスの効果について

  水産工学会誌  36-  (1)  71  -74  1999  [Not refereed][Not invited]
  
• Theoretically Prediction of the Wave Exciting Force and Hydrodynamic Coefficients on a Raft for an Aquacutural Net Cage

  TAKAGI Tsutomu  Fisheries Engineering  Vol.35-  (3)  271  -281  1999  [Not refereed][Not invited]
  
• 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  [Not refereed][Not invited]
  
• 水中マイクロスコープの試作とその操作試験結果

  水産工学会誌  35-  (2)  153  -158  1998  [Not refereed][Not invited]
  
• Calculation of Wave Deformations around Submerged Plates in Finite Water Depths by Solving Linearized Three-Dimensional Wave Diffraction Problems Using the Hybrid Method

  TAKAGI Tsutomu, HIRAISHI Tomonori, YAMAMOTO Katsutaro, NASHIMOTO Katsuaki  Fisheries engineering  Vol.34-  (1)  23  -32  1997  [Not refereed][Not invited]
   

  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。
• Calculation of Wave Deformations around Submerged Plates in Finite Water Depths by Solving Linearized Three-Dimensional Wave Diffraction Problems Using Hybrid Methods.

  TAKAGI Tsutomu, HIRAISHI Tomonori, YAMAMOTO Katsutaro, NASHIMOTO Katsuaki  Fisheries Engineering  34-  (1)  23  -32  1997  [Not refereed][Not invited]
   

  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。
• Stationary Ability of Bastard Halibut Paralichthys olivaceus and Longsnout Flounder Limanda punctatissima to Water Current at the Bottom of a Net Cage

  Tomonori Hiraishi, Katsuaki Nashimoto, Tsutomu Takagi, Kengo Suzuki, Keiichiro Motomatu*  NIPPON SUISAN GAKKAISHI  61-  (3)  363  -368  1995  [Not refereed][Not invited]
   

  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.
• Selectivity of Traps for Whelks Neptunea arthritica

  Katsuaki Nashimoto, Kengo Suzuki, Tsutomu Takagi, Keiichiro Motomatsu, Tomonori Hiraishi  NIPPON SUISAN GAKKAISHI  61-  (4)  525  -530  1995  [Not refereed][Not invited]
   

  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.
• ウニの付着基質の違いによる移動特性および水平・鉛直壁面に対する行動能力

  水産工学会誌  32-  (1)  39  -43  1995  [Not refereed][Not invited]
  
• 線形ディフラクション問題におけるハイブリッド法による一解法

  水産工学会誌  32-  (2)  127  -135  1995  [Refereed][Not invited]
  
• Catch Efficiency of Japanese Surf Clam Hydraulic Jet Dredge

  Katsuaki Nashimoto, Tomonori Hiraishi, Tsutomu Takagi, Keiji Matsuyama  Nippon Suisan Gakkaishi (Japanese Edition)  60-  (1)  79  -83  1994  [Not refereed][Not invited]
   

  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

  傅 恩波, 梨本 勝昭, 山本 勝太郎, 平石 智徳, 高木 力  北大水産彙報  45-  (1)  9  -18  1994  [Not refereed][Not invited]
  
• 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  [Not refereed][Not invited]
  
• 形状と大きさの異なる水槽内における魚群行動について

  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  [Not refereed][Not invited]
  

Books etc

• Contributions on the theory of fishing gears and related, Marine systems

  2002
• 漁具物理学

  成山堂書店 2001
• Fishing Gear Phisics

  2001
• Contributions on the Theory of Fishing Gears and Related Marine Systems

  NEUER HOCHSCHULSCHRIF TENVIRLAG 2000

Association Memberships

• 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   

Research Projects

• 鰭の柔らかさと動きのしなやかさがもたらす移動能力と機動性向上の解明

  日本学術振興会：科学研究費助成事業 基盤研究(C)

  Date (from‐to) : 2022/04 -2025/03 

  Author : 高木 力, 鳥澤 眞介, 竹原 幸生
• 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)

  Date (from‐to) : 2020/04 -2023/03 

  Author : 鳥澤 眞介, 竹原 幸生, 高木 力

   

  賢く獲る漁業技術の開発が近年求められているが，生産手段の最適化は対象生物(魚類)の行動特性を理解せずには実現できない。したがって，魚類の群行動についての基本的理解とそのための研究は不可欠である。 本研究では，魚類が群れを形成する意味を物理的側面からアプローチすることにより，その本質的意義の解明を目指す。背景となる力学的論理基盤から群を形成したことによる移動エネルギーコストの利得が単一個体よりどの程度のアドバンテージとなり，魚群の規模によりどのような差がでるのかを明らかにする。これをベースにして，種の違いによる魚群の移動距離・速度とエネルギーコストの適値と限界，また群を形成する種がなぜその魚群規模となるのか，その極限や最適規模，さらに魚群の立体構造の必然性や最適性について，一つの体系的理論からこれらの説明や解釈を可能とする革新的アプローチ手法の確立を試みている。 PTV（流体可視化計測）実験では，マアジを対象種として3尾で形成される魚群を回流水槽で巡航遊泳させ，群泳時の魚体後流域の流況可視化実験を2種類のレーザー光源と高速カメラを用いて2日間にわたり2回実施した。現在は当該実験で撮影した画像から流況を明かにするために，魚体後流域の流速ベクトルや渦度分布の解析を実施中である。 CFD（数値流体力学）解析実験では，ビワマスを対象種としてデジタルビデオカメラで撮影した遊泳運動から魚体の遊泳運動関数を算定した後，並列遊泳する2尾の魚体モデルに遊泳運動を与えて群泳を再現し，数値流体力学解析により魚体モデルに作用する圧力とその分布を算出することで流体力学的効果を求めた。並列で遊泳する個体は個体間の距離を全長の0.4倍から2.0倍まで変化させた場合，0.4全長倍距離のとき推進効率が最も良く，尾鰭の振動が互いに逆位相のとき，単体で遊泳するよりも推進効率が約10%向上することを明かにした。
• 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)

  Date (from‐to) : 2018/04 -2022/03 

  Author : 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。
• Development of algorithm for number of swimming fish individuals: a new approach by using PTV technique

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

  Date (from‐to) : 2015/04 -2017/03 

  Author : KIMURA Nobuo, KOMEYAMA Kazuyoshi, TORISAWA Shinsuke, HIRAISHI Tomonori

   

  To develop the fundamental technique of counting number of fish individuals in an aquaculture cage, the basic algorithm for counting individuals was constructed by applying PTV (Particle Tracking Velocimetry) technique. The region above a certain area and brightness was defined as the candidate region of an individual. The movement vectors of the extracted regions were estimated by using Kalman filter, and the number of the vectors was possible to give that of individuals. When 200 individuals were put in an experimental tank, applying the algorithm showed that the averaged error was 5.9% and its availability was confirmed.
• Elucidation of capture process and mechanism of purse seine tuna fishing by using ICT

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

  Date (from‐to) : 2014/04 -2017/03 

  Author : Takagi Tsutomu, TORISAWA Shinsuke, MITSUNAGA Yasushi, KAWABE Ryo, KADOTA Minoru

   

  To assess the capture process during purse seine fishing of tuna species, the dynamic geometries of the purse seine fishing net under some operations were investigated by using a numerical simulation technique as well as by obtaining three-dimensional swimming paths of three bigeye tuna individuals during the purse seine fishing operation through dead-reckoning algorithms. The vectors of the swimming paths showed great variations in the vertical and horizontal directions. The hem of the purse seine net reached up to 200 m in depth, whereas the tuna individuals swam at depths shallower than 100 m and their swimming speeds decreased by 30% after pursing. The simulation results revealed that by 1500 s after casting the net, immature bigeye tunas could not pass through the body net because of the meshes of the net stretching in the longitudinal direction.
• Development of multi-dimensional information gathering system by using a collective motion control of aerial and ground vehicles

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

  Date (from‐to) : 2011/04 -2014/03 

  Author : INADA YOSHINOBU, TAKANOBU Hideaki, TAKAGI Tsutomu

   

  Biologically-inspired collective motion control was investigated to enhance the availability of mini-size air vehicles or ground vehicles for information gathering. The control model consists of three components, i.e. attraction, repulsion, and parallel orientation, which are based on the motion of fish school or bird flock. The effectiveness of the model was tested on the various types of vehicles, e.g. ground vehicles, airship, fixed and rotary wing type airplanes. In consequence, all or a part of the three components of collective motion control were successfully functioned on these vehicles. Furthermore, the cooperation between heterogeneous vehicles, i.e. airship and ground vehicles, was succeeded. The characteristics of fish school were also investigated and the change of group formation parameters with the stage of growth and the optimal positioning of individuals in the school to reduce the energy consumption were clarified.
• Optimum design for an offshore aquaculture facility for Pacific bluefintuna on the basis of its behavioral aspects

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

  Date (from‐to) : 2010 -2012 

  Author : TAKAGI Tsutomu, KOMEYAMA Kazuyoshi, TORISAWA Shinsuke, SUZUKI Katsuya, KAWABE Ryo, KADOTA Minoru

   

  In the present study, we tried to create the basis for an optimum design for an offshore aquaculture facility for Pacific bluefin tuna (PBT) from not only mechanical aspects but also biological ones after considering the behavior of PBT. We used a numerical simulation system of the netting geometry developed by us to evaluate net deformation and the loads to the facility. The simulation results showed that the net cage was deformed and reduced to 50% of the original volume by current flow when the speed was 1 kt. The observation data obtained using a bio-telemetry system showed that the strong current blew up the net cage and caused a collision between the netting and the cultured tuna. In addition, the cold water mass acted as a strong constraint factor on the vertical swimming of PBT.
• Analysis of the swimming behavior of cultivated Pacific bluefin tuna following a change in environment

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Research Activity Start-up

  Date (from‐to) : 2009 -2010 

  Author : KOMEYAMA Kazuyoshi, TAKAGI Tsutomu, TORISAWA SHINSUKE, SUZUKI Katsuya, KADOTA MINORU

   

  To examine responses to environment changes, we monitored the behavior of cultivated Pacific bluefin tuna in a submerged aquaculture net cage. We confirmed notable changes in the swimming depth of fish when cold water was added to the aquaculture net cage. Additionally, we successfully measured the three dimensional swimming path of the fish. This will enable us to evaluate which factors (i.e., a change in the living space of the submerged net cage by upward or downward movement or a decreased volume caused by ocean currents) affect the behavior of the fish by reconstructing their swimming paths.
• Swimming performance of the bluefin tuna: Research with an integrated biomechanics-and biotelemetry-based approach

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

  Date (from‐to) : 2006 -2007 

  Author : TAKAGI Tsutomu, KAWABE Ryo, MITSUNAGA Yasushi, UENO Kimihiko

   

  The purpose of this study is to elucidate the morphology, activity, and swimming mechanism of the bluefin tuna by using an integrated biomechanical-and biotelemetry-based approach. The fluid dynamic properties of bluefin tuna were estimated by computational fluid dynamics (CID) analysis. The coefficients of drag on bluefin tuna decrease as the fish grows. The drag during swimming depends on the amplitude of caudal-fin oscillation but not on its frequency. The theoretical results of CID revealed that the fish swims with its head tilted upward during slow cruising in order to maintain mechanical balance with equilibrium state of the moment around its center of gravity. A coupling glide with a large head-tilt angle and upward swimming with a small angle enable the fish to energetically and efficiently cover long distances. These theoretical results were confirmed by field data obtained using a data logger that can record the depth, head-tilt angle, and tail-beating activity of a tuna during swimming. It is believed that the pectoral fin of the bluefin tuna, owing to its negative buoyancy, produces a lift force that supports the submerged weight of the fish. We therefore performed CID analysis to confirm the function of the pectoral fin. For this purpose, we developed a novel data logger that records the movement of the pectoral fin toward or away from the body by using a magnetic sensor. The recorded data revealed that the fish often extends its fin during slow swimming in order to produce the required lift force. To estimate the efficiency at which metabolic energy is converted to external work during swimming, we performed experiments using a water tunnel. The cost of transport (COT) for a young bluefin tuna is approximately 15000 J・kg^<-1>・km^<-1>. However, on the basis of the CFD analysis, we estimated the external work for swimming to be 2-4% of the COT; this suggests that the bluefin tuna can use most of its metabolic energy to maintain its body temperature.
• 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

  Date (from‐to) : 2003 -2007
• 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

  Date (from‐to) : 2004 -2006
• クロマグロ等魚類養殖施設の最適構造の検討

  Date (from‐to) : 2003 -2004
• 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)

  Date (from‐to) : 2001 -2002 

  Author : 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

  Date (from‐to) : 2002
• Hydromechanical study of swim-and-glide behaviour on free-ranging flatfish

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

  Date (from‐to) : 2000 -2001 

  Author : NASHIMOTO Katsuaki, TAKAGI Tsutomu, HIRAISHI Tomonori, NAITO Yasuhiko

   

  Intermittent swimming behaviour of marine fish with negative buoyancy, such as swim-glide behaviour, has been hypothesized to result in a saving of energy required for locomotion between two points. However, there have been no studies that tried to prove this hypothesis in the wild. This has been due in part to the difficulty of observing and monitoring free-ranging fish in the open sea. Previous conventional tagging experiments have indicated that Japanese flounder, Paralichthys olivaceus, sometimes migrated in the far distance, recaptured 1,000 km from the point of release, despite their lower swimming ability and morphological feature without swim bladder. In order to measure energetic cost of free-ranging flatfish during migration, it is important to know the activity and time budgets of flatfish on its migration route. Using a depth and acceleration data-logger on Japanese flounders, we obtained continuous record of swimming speed, depth, tailbeat activity and swimming angle of free-ranging flounders, simultaneously. We estimated and compared the migrating energy costs during continuous swim and swim-glide. We were successful in direct measurement of swim-glide behaviour from flatfish using tailbeat profiles recorded by the logger for the first time. Compared the migration cost between continuous swim and swim-glide, covering similar distance, migration by adopting swim-glide technique resulted in a 22.3% reduction in number of tailbeats. Thus, this energy-saving strategy allows flatfish with negative buoyancy to migrate the long-distance.
• 定置網内の魚群行動モデル

  Date (from‐to) : 2001
• 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

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• 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  

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