南海区拖网方目网囊选择性试验

Selective Experiments of Square Mesh Cod-End of Bottom Trawl in South China Sea

为了科学地确定南海区拖网网囊的结构和适宜网目尺寸 ,于 2 0 0 0年 1 1月 2 5日～ 1 2月 2 0日在南海北部珠江口以外海域水深 36～ 70m拖网渔场 ,对 4种不同网目尺寸的方目网囊进行了网囊套网式捕鱼选择性试验 ,获得了蓝圆鱼参(Decapterusmaruadsi)、多齿蛇鲻 (Sauridatumbil)、条尾绯鲤 (Upeneusbensa si)等 3种主要鱼种的选择性曲线。试验结果表明 :4种方目网囊的数量平均逃逸率均高于重量平均逃逸率 ;网囊渔获的优势体长总是大于套网渔获的优势体长 ;蓝 鱼参、多齿蛇鲻、条尾绯鲤之类的圆体鱼类比扁体鱼类更易于逃出方目网囊。

To determine scientifically the design and optimum mesh size of bottom trawl codend in South China Sea, selective fishing experiments were carried out for four covered square mesh cod-ends of different mesh sizes between 25 November and 20 December 2000 in the Pearl Estuary trawling ground, at depth 36～70 m, off the northern South China Sea. We obtained selectivity curves of three important species of fish, Decapterus maruadsi, Saurida tumbil and Upeneus bensas. The experiments showed that a mean escape rate of these four cod-ends were greater in number than in weight; Dominant body length of fish caught in the cod-ends is always longer than that of fish caught in the cover-net; Round-shaped fish such as Decapterus maruadsi, Upeneus bensasi and Saurida tumbil are much easier to escape from square mesh cod-end than flat-shaped fish.