南海马鲛流刺网网目对康氏马鲛的选择性研究

为研究南海马鲛流刺网网目对康氏马鲛Scomberomorus commersoni的选择性,于2015年3月在南海北部用网目尺寸分别为80、100、120、138、142、160 mm的刺网进行了共同捕捞试验,基于SELECT(Share Each LEngth's Catch Total)模型的基本架构下,用Normal和Bi-normal选择性概率模型拟合试验数据,并就刺网对康氏马鲛的渔获方式、选择性曲线形状和SELECT模型应用展开了探讨。结果表明:试验共捕获康氏马鲛172尾,康氏马鲛的渔获方式以刺挂为主;Normal和Bi-normal的估计分隔模型均比等分隔模型拟合效果好,其中Bi-normal的估计分隔模型拟合效果最好,两个选择性峰值点对应的相对叉长分别为R_a=4.4399和R_b=6.7278;6组网目尺寸的刺网对康氏马鲛的相对作业强度(pi)大小依次为138 mm142 mm160 mm100 mm80 mm120 mm。本研究结果可为制定南海马鲛流刺网最小网目尺寸提供参考。

Size selectivity of gillnets for narrowbarred king mackerel Scomberomorus commersoni in South China Sea

Fishing experiments were carried out by gillnets with mesh size of 80 , 100 , 120 , 138 , 142 and 160 mm in northern South China Sea in March 2015 to investigate the size selectivity of gillnets for narrowbarred king mack-erel Scomberomorus commersoni. The selectivity data of gillnets were simulated and evaluated based on the SELECT ( Share Each LEngth’s Catch Total) method by both Normal and Bi-normal models. A total of 172 individuals of narrowbarred king mackerel were captured and most captured by the gillnets. There was better modeling result in estimated split models, in both Normal and Bi-normal models, than that in equal split models. The estimated split model of Bi-normal showed the best fit to the catch data, and was chosen as the best fit model. The first and sec-ond of the modal relative length of this model was 4. 439 9 and 6. 727 8, respectively. The order of relative fishing intensity of gillnets to narrowbarred king mackerel was ranged as 138 mm>142 mm>160 mm>100 mm>80 mm>120 mm. The fishing mechanism of gillnets to narrowbarred king mackerel, the shape of selectivity curve and the use of SELECT model were discussed in this article. The findings can be used to promulgate minimal mesh size of gillnets for narrowbarred king mackerel in South China Sea.