黄海双船有翼单囊拖网网囊最小网目尺寸研究

为支撑《全国海洋捕捞渔具目录》的实施与管理,针对黄海双船有翼单囊拖网的网目选择性,于2017年8月在黄海南部的海州湾水域进行了不同网囊网目尺寸(40、54、60、70、90 mm)的套网法拖网试验,通过分析不同网目尺寸(40、54、60、70、90 mm)下主要渔获的逃逸率与幼鱼的释放效果,并结合数学建模方法对生态效益和经济效益进行了权衡研究。结果表明:随着网囊网目尺寸的增大,渔获逃逸率逐渐增加,对幼鱼的释放效果显著,从生态保护方面考虑,根据目前的资源状况,网囊网目尺寸可放大至80 mm以上;当网囊网目尺寸小于56 mm时,释放效果显著,当网目尺寸大于56 mm时,经济效益损失显著。研究表明,为了权衡生态效益和经济效益,建议将56 mm作为制定黄海双船有翼单囊拖网网囊最小网目尺寸的参考标准。

Minimal cod-end mesh of a pair trawl in the Yellow Sea

The escape rate of main catches and release of juvenile fish were studied using a pair trawl with double wings and single cod-end by cover-nets with cod-end mesh of 40,54,60,70 and 90 mm in Haizhou Bay in the southern Yellow Sea in August 2017 in order to support the implementation and management of Natural Marine Fish-ing Gear Catalog and study the selectivity of cod-end mesh of pair trawl with double wings and single cod-end. A balance of ecological effectiveness and economic effectiveness was made with a mathematical modeling method. It was found that the escape rate of fish was increased gradually with the increment in cod-end mesh size, and that the release effect of juvenile fish appeared to be elevated significantly. The mesh size of cod-end was shown to be enlarged to more than 80 mm based on the ecological protection under the present fishery resources in the Yellow Sea. The remarkable release effect was observed at the mesh size of < 56 mm,and the significant loss of economic effectiveness was found at the mesh size of > 56 mm. Therefore it is suggested that the mesh size of 56 mm be of scientific reference to the standard of the minimum cod-end mesh size of pair trawl in the Yellow Sea in order to balance the ecological effectiveness and economic effectiveness.