Behavioral Physiology of Fish in Capturing Process of Mid-Water Trawl

该研究项目涉及在中层水拖网捕鱼的捕获过程中目标鱼种的行为生理与渔具几何形状的关系，包括三个主题;渔具几何形状和控制的分析，目标鱼类对渔具的反应，以及狭鳕的视觉生理和游泳生理。在北方近海拖网渔船上，声学遥测观测是为了了解网具的静态和动态几何形状，如网口的深度、高度和宽度以及水獭门的距离。拖航过程中影响网形的诸因素与拖航速度和拖航长度相对应。根据声学测试结果，分析和讨论了在甲板上撒网和拖网的工作周期，并结合大眼鳕的视觉生理，对大眼鳕的眼球进行了机载取样，以确定视网膜适应性， 关于我们 拖航深度和时间在200米或更深的渔场白天取样，显微镜检查显示视网膜不完全光适应。这表明它不能辨别颜色，但对弱光强度有较高的敏感性。此外，还利用透镜大小和视网膜视细胞密度的数据，测定了视敏度，从而估算出理想状态下鱼体大小的最大视距。T.为了测定狭鳕的光镇静性，还进行了光的波长、时频、强度、刺激、比较了不同光照条件下视网膜的光适应和暗适应。行为生理学的另一个重要因素是鱼类的游泳性能，因为肌肉活动与鱼类对光的反应有关。被拖走的装备从尺度效应和温度效应的角度，进行了船上和实验室实验，测量肌肉收缩时间。根据结果，确定了最大尾拍频率。此外，在坦克的游泳行为进行录像，以获得数据的步幅每I尾拍。最后，结合温度依赖性，对最大游动速度进行了估算。温度对肌肉收缩时间的影响结果表明，在较高的温度下，鱼的游泳性能更好。这意味着在水温相对较高的中层拖网作业中需要相对较高的拖曳速度。少

The research project deals with the behavioral physiology of target species in relation ot the gear geometry in the capturing process of mid-water trawl fishing, consisted of three main themes ; the analysis of gear geometry and control, the reaction of targeted fish towards the gear, as well as the visual physiology and the swimming physiology of walleye pollock, Theragra chalcogramma.On board the northern off-shore trawlers, the acoustic telemetry observation was conducted to understand the static and dynamic geometry or net gear ; such as the depth, height and width of net mouth and the otterdoors distance. These factors of net shape during towing were corresponded to the Lowing speed and warp length. From the acoustic results, the deck working cycle for the net shooting and hauling procedures was analyzed and discussed.Concerning the visual physiology of walleye polloock, on-board sampling of eyeball was conducted for the purpose to identify the retina adaptation in relation to the … More towing depth and time of day. The microscopic examination-snowed that the retina was not fully light-adapted Pven with the daytime sampling in the fishing ground of 200m or deeper. It indicates the incapability of colour discrimination but the higher sensitivity to the weak light intensity. Besides, with the data of lens size arid visual cell density on the retina, the visual acuity was determined so as to estimate the maximum sighting distance accordinig to the size of fish in the ideal condition. T. n order to determine Lhe light sedsitivity of walleye pollock, the electrophysiological experiments were also conducted with the variation of the wave-length, durationl/frequencies and intensity of light, stimuli, in comparison between light and dark adaptation of retina under the various lighting conditions.Another important factor of behavioral physiology is the swimming performance of fish as the muscle activity in relation to the reaction of fish toward the towed gear. On-board and laboratory experiments was conducted to measure the muscle contraction time from the view point of the scale and temperature effect. From the results, the maximum tail beat frequency was determined. In addition, the swimming behaviour in tank was video-recorded to obtain the data for the stride length per I tail beat. As the final, the maximum swimming speed was estimated with the special reference of the temperature dependence. The results of temperature effect on muscle contraction time indicate better swimming performance of fish at higher temperatures. This implies that a relatively higher towing speed is required in mid-water trawling in which water temperature is relatively high. Less