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

保护性捕捞技术是21世纪渔业可持续发展的未来目标。为了发展这一新概念，结合拖网、围网、刺网、定置网和延绳钓等不同渔具的捕获过程，研究了鱼类逃离渔具后的压力和存活情况。作为本课题研究的第一步，本文首先对国内外有关鱼类应激反应的研究进行了综述。对于应激测量，用放射性同位素技术研究了由于处理和捕获过程引起的血浆皮质醇水平的变化。心电图（ECG）生物遥测技术也被用来测量实时响应的装置pingger发射器。这两种方法都成功地确定了鱼的应激反应，在实验中的几个不同的渔具。在这些实验中，根据捕获后和释放或逃离齿轮后的时间顺序，还检查了鱼类的损伤和存活。结果表明，每种渔具具有不同的捕获机理，从而表现出不同的受力情况。例如，延绳钓渔具对捕获的鱼更友好，即即使在捕获条件下，由于自由游动而产生的压力也较小。相反，刺网会严重损害鱼类，因此可以记录立即或延长死亡时间。这些条件的鱼可以分析与血浆皮质醇水平的关系，每一个渔具的应激强度。

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.