基于SELECT模型的南海金线鱼刺网选择性研究

Size selectivity of gillnet fishery for Nemipterus virgatus in the South China Sea based on SELECT method

    摘要
  • 摘要: 为研究流刺网网目尺寸对金线鱼(Nemipterus virgatus)的选择性，2008年5月于南海北部渔场用网目尺寸分别为40 mm、45 mm、50 mm、55 mm和60 mm的刺网进行了共同捕捞试验。在SELECT(Share Each LEngthclass′s Catch Total)模型的架构下，用Normal、Gama和Bi-normal概率模型拟合刺网对金线鱼的选择性，根据赤池信息指数(Akaike′s Information Criterion，AIC)值评价并选出最佳拟合模型。结果表明，试验共捕获金线鱼185尾，金线鱼众数体长随网目尺寸的增加而增大；Gama的估计分隔模型AIC值在所有模型中最小(466.55)，将其作为最佳拟合模型；刺网对金线鱼的相对作业强度(Pi)大小顺序依次为40 mm>60 mm>55 mm>45 mm>50 mm；40 mm、45 mm、50 mm、55 mm和60 mm刺网对体长150 mm金线鱼的选择率分别为98.39%、80.94%、39.30%、13.70%和3.87%。该研究认为将50 mm作为金线鱼刺网的最小网目尺寸不足以达到保护渔业资源的目的，建议将南海区金线鱼刺网最小网目尺寸增加到55 mm。

     

    Abstract: We carried out fishing experiments with gillnets of five different mesh sizes(40 mm, 45 mm, 50 mm, 55 mm and 60 mm)in fishing grounds of the northern South China Sea in May 2008, to investigate the size selectivity of gillnets for Nemipterus virgatus. Three function models (Normal, Gama and Bi-normal) were used to calculate the selectivity of gillnet for N. virgatus based on SELECT (Share Each LEngthclass′s Catch Total) method. By comparing the AIC (Akaike′s Information Criterion) value, the best fit model was chosen. The results show that 185 specimens of N. virgatus were collected, and their modal lengths group increased as the mesh size increased. As with the lowest AIC value (466.55), the estimated split model of Gama was regarded as the best fit model. The descending order of relative fishing intensity (Pi) of gillnet for N. virgatus was 40 mm>60 mm>55 mm>45 mm>50 mm. The selectivities of 150 mm-length N. virgatus were 98.39%, 80.94%, 39.30%, 13.70% and 3.87% for gillnets with 40 mm, 45 mm, 50 mm, 55 mm and 60 mm, respectively. Finally, the minimal mesh size of gillnets for N. virgatus was suggested as 55 mm for protection of fisheries resources.

     

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