对虾流网掉虾原因分析及其补救的技术措施

渤海、黄海北部秋汛捕捞对虾,以往主要使用拖网。为保护渔场水域的生态环境和幼鱼(幼体)资源,通过针对虾类行动的实验性观察,同时使用流网试捕。分析流网掉虾的原因和提出防范掉虾的技术措施,以便更好地实现“以流网代替拖网捕捞对虾”的技术改革。

TECHNICAL PRECAUTIONS AGAINST DROPPING OF BLOCKED PRAWN FROM DRIFT NET IN PRAWN FISHING

In the autumn harvest season of Bohai Sea and northern Yellow Sea,the Chinese prawn (Penaeus orientalis) was traditionally caught by using varioustrawlnets. In order to protect environmental conditions of fishing ground and tosave the juvenile fishery potentiality, in 1983-1985 the behaviour of penaeidprawn was observed and trial fishing by drift net was taken as well. From thepractice a certain amount of blocked prawn dropped from the drift-net webbingoccurred. By analysing, the technical precautions against the dropping were sug-gested: 1. The each main webbing of per drift net should be used traverse. The hori-zontal hanging coefficient (u_1) should increase from 0.67 to 0.71. And the meshsize (2a) may be more than 62 mm. 2. Through diving observations, no such dropping was found during the haulfrom bottom to the surface. In the haul time, the hauling speed of float line, leadline and webbing of net should be equal, meanwhile to keep the side of net web-bing against current upwards. 3. During the haul, it is necessary for using the floating prawn pocket to de-crease the dropping blocked prawn.