基于不同权重栖息地模型的秘鲁外海茎柔鱼渔场分析

Analysis of fishing ground of jumbo flying squid Dosidicus gigas in the southeast Pacific Ocean off Peru based on weighting-based habitat suitability index model

根据2006—2014年春季(9—11月)、夏季(12月—翌年2月)、秋季(3—5月)和冬季(6—8月)秘鲁外海茎柔鱼渔获数据,结合3个关键海洋环境因子:海表面温度(sea surface temperature,SST)、海表面高度(sea surface height,SSH)和净初级生产量(net primary production,NPP),利用不同权重方案的栖息地适宜性指数模型分析秘鲁外海茎柔鱼渔场分布。利用捕捞努力量与SST、SSH和NPP建立适宜性指数(suitability index,SI)模型,采用算术加权法建立综合栖息地适宜性指数(habitat suitability index,HSI)模型,依据渔获量和捕捞努力量的比例比较不同权重的HSI模型,选择不同季度的最优模型,并用2015年的数据进行验证。结果显示,茎柔鱼CPUE和渔场纬度重心(latitudinal gravity centers of fishing ground,LATG)呈现显著的年际和季节变化。在年际变化上,CPUE基本在2~7 t/d浮动,纬度重心基本维持在10°S~18°S;在季度变化上,冬春季的CPUE高,渔场纬度重心偏向北部海域,夏季,CPUE随着纬度重心的南移而增加,与春季相比,栖息地南移1.5°,CPUE增加6.7%,秋季渔场纬度重心最靠南,CPUE最低。不同季节的最优栖息地模型中的权重方案不同,冬春季最优模型权重方案为模型9,权重最高的环境因子是SST;夏季最优模型权重方案为模型7,SST、SSH和NPP权重相等;秋季最优模型权重方案为模型3,权重最高的是SSH。以上结果表明环境因子在每个季度中对秘鲁外海茎柔鱼的栖息地影响程度不同。春夏秋冬各季度最优模型预测的精度分别为84.68%、78.56%、72.74%和68.70%。本研究有利于了解不同季度时间尺度下环境因子对秘鲁外海茎柔鱼的影响情况,为指导鱿钓渔业生产提供科学依据。

According to the fisheries data of Dosidicus gigas off Peru in the spring(August to October),summer(November to January),autumn(February to April)and winter(May to July)from 2006 to 2014,combined with three key marine environmental factors:sea surface temperature(SST),sea surface height(SSH),and net primary production(NPP),habitat suitability index models(HSI)with different weighting scenarios were employed to predict the fishing ground distribution of Dosidicus gigas off Peru.The relationship between catch per unite effort(CPUE)and SST as well as SSH and NPP was used to establish a suitability index(SI)model for each factor,and the arithmetic weighting method was applied to develop an integrated HSI model.Based on the proportions of catch and effort at each HSI class interval from the different weighted HSI models,the optimal models for different seasons were selected.The HSI model was validated by the data from 2015.The results showed that,the CPUE and the latitude gravity center of fishing ground(LATG)showed significant interannual and seasonal changes.In terms of interannual changes,CPUE basically fluctuated between 2 and 7 t/d,and the LATG basically ranged from 10°S to 18°S.On the seasonal change,CPUE in winter and spring was high,and the LATG was located in the northward regions on the fishing ground.In summer,the CPUE increased with the southward shift of the LATG.Compared with spring,the habitat moved 1.5°southwards and the CPUE increased by 6.7%.The change trend in autumn was the same as in winter and spring.The weighting schemes of the optimal habitat model in different seasons were different.The optimal weighting scheme of the spring was Case 9;the environmental factor with the highest weight was SST;the optimal weighting scheme of the summer was Case 7,and SST,SSH,and NPP weights were equivalent;the optimal weighting scheme for the autumn was Case 3,and the highest weighting was SSH.The above results indicated that the environmental factors had different impacts on the habitats of the Dosidicus gigas off Peru in each season.The accuracy of habitat predictions for each season was 84.68%,78.56%,72.74%,and 68.70%.It was helpful to understand the impacts of environmental factors on Dosidicus gigas stocks off Peru at different seasons,providing a scientific basis for the distant-water operations of Chinese squid-jigging fisheries.