Behavioral Physiology Research on Survival of Fish after Escape from Fishing Gears

点击翻译按钮获取中文摘要

Conservation Harvesting Technology is the future goal for the sustainable fisheries towards the 21st Century. To develop this new concept, the stress and survival of fish after escape from the fishing gears have been examined in relation to the capture process of different fishing gears such as trawl, purse seine, gill-net, set-net and longline. As the first step of this research, previous works on the stress response of fish were reviewed from the various kind of sources around the world. For the stress measurement, the change of plasma cortisol level due to the handling and capture process was investigated with the radio-isotope techniques. The electrocardiogram (ECG) bio-telemetry technique was also employed to measure the real-time response by means of pingger transmitter. Both two methods were successful for determining the stress response of fish in relation to the experimental fishing by several defferent gears. The damage and survival of fish was also examined during these experiment according to the time sequence after being captured and after being released or escaping from the gears. As the results, each fishing gear has the defferent capture mechanism, so as to show the different stress aspects. For example, the longline gear is more friendly to the captured fish, i.e.less stress due to the free swimming even in the captured conditions. On the contrary, the fish can be damaged severely by the gill-net, so that an immediate or elongated death can be recorded. These condition of fish can be analyzed with the plasma cortisol level in relation to the stressor intensity of each fishing gear.