东海区单层流刺网对棘绿鳍鱼的选择性

The mesh size selectivity of gillnets to Chelidonichthys spinosus in the East China Sea

为了明晰东海区单层流刺网对棘绿鳍鱼的选择性特征,开展不同网目尺寸（45、50和55 mm）和网片高度（6和10 m）的单层流刺网生产实验。结果显示,不同实验网渔获物中棘绿鳍鱼体长频率呈单峰分布;选用Normal、Lognormal和Gamma模型对渔获数据进行拟合,并使用极大似然法估算模型参数,似然比卡方检验和赤池信息系数（AIC）比较表明,Lognormal模型拟合效果最佳,其卡方值为30.65,明显小于临界值,AIC值为147.78,模型曲线向右倾斜明显,峰值左侧选择率递增较快,右侧下降缓慢,与原始数据相符;50 mm网目50%选择性体长为123 mm,有效捕捞体长范围为123~209 mm;根据遭遇网具的棘绿鳍鱼资源结构估算结果,实验海域棘绿鳍鱼体长频率呈正态分布,优势体长范围为125~185 mm,与早期研究结果相近;50 mm网目有效捕捞体长范围与当前资源优势体长范围相近,可实现捕捞效率的最大化;总体上两种高度（6和10 m）实验网渔获物中,棘绿鳍鱼体长频率分布相似,优势体长范围相近,上述两种网片高度对棘绿鳍鱼资源的影响差异不显著。上述研究结果可为近海渔业生产和管理提供参考。

In order to find the selectivity of gillnets in the East China Sea, a production test using several gillnets of various mesh sizes（45,50 and 55 mm）and two gear heights（6 and 10 m）was carried out. Three uni-models（Normal, Lognormal and Gamma）were used to analyze the selectivity of the test nets. The parameters were estimated using maximum like lihood methods. Likelihood ratio Chi-square test and Akaike＇s information criterion（AIC） were used to compare the goodness of fit of the different models.Theresult showed that the fitting goodness of lognormal model is the best.The model is lower than, AIC is 147.78. The right tilt of the lognormal is obvious,the selectivity increased faster at the left side of the model peak, and gentle decline at the right side, which are well coincided with the original data.The 50% select body length of 50 mm mesh size is 123 mm, the select range is123-209 mm. According to the population structure estimation which contacted test nets, the catch number of different body-length groups is normally distributed, the dominant range is 125-185 mm, this result is similar to previous studies. The select range of 50 mm mesh size covered the estimated dominant range, 50 mm mesh size is the most efficient for Chelidonichthys spinosus, but the influence of the mesh size on the fishery resources can not be evaluated due to the lack of knowledge about C. spinosus resources situation; the catches of the two heights test nets（6 and 10） are similar. The influence of panel heights to catches of C. spinosus is not obvious. These lesults will provide scientific guideline for coastal fishery management.