东太平洋不同海域环境因子对茎柔鱼分布的影响差异分析

Difference of the effects of environmental factors on habitat distribution of Dosidicus gigas in different regions in the Eastern Pacific Ocean

为探究东南太平洋不同海域环境因子对茎柔鱼栖息地分布的影响差异,利用东太平洋2016—2018年赤道海域、秘鲁外海与2015—2017年智利外海3个海域茎柔鱼渔业生产数据,选取海表面温度(Sea surface temperature,SST)、涡旋动能(Eddy kinetic energy,EKE)、海表面盐度(Sea surface salinity,SSS)、海表面高度(Sea surface height,SSH)、叶绿素a质量浓度(Chlorophyll-a,Chl.a)、混合层深度(Mixed layer depth,MLD)、溶解氧质量浓度(Dissolved oxygen,DO)等7个海洋环境因子,建立最大熵模型以探究不同海域夏、秋两个季节内茎柔鱼适栖息地分布情况以及探究环境因子对其影响的差异。结果显示,各海域不同季节最大熵模型的受试者工作特征曲线下面积(Area under the curve,AUC)均大于0.8,实际捕捞位置与模型拟合的适宜栖息地范围重合。3个海域适宜栖息地的变化情况如下:赤道夏季最适栖息地主要分布在110°W~120°W、1°N~3°S海域;秋季,茎柔鱼最适栖息地主要分布在97°W~117°W、1.5°N~1.5°S海域,栖息地分布向东延伸。秘鲁外海夏季最适栖息地主要分布在75°W~86°W、15°S~20°S海域;秋季,茎柔鱼最适栖息地主要分布在75°W~84°W、15°S~20°S海域,夏季到秋季最适宜栖息地整体向东南方向移动。智利外海夏季茎柔鱼最适栖息地主要分布在73°W~85°W、20°S~30°S海域;秋季最适栖息地主要分布在75°W~85°W、20°S~28°S海域,夏季到秋季适宜栖息地整体向东北缩减。最大熵贡献率结果显示,影响赤道、秘鲁和智利外海茎柔鱼分布的重要环境因子分别为SSH、Chl.a、SSS、SST;SSH、MLD、DO、SST和SSH、SST、Chl.a、MLD。研究表明,不同海域影响茎柔鱼分布的环境因子具有显著的地域差异。

Jumbo flying squid Dosidicus gigas is widely distributed in the Eastern Pacific Ocean.It has a short-lived life cycle and tends to extremely respond to environmental and climate variability.In order to investigate the difference of the effects of environmental factors on habitat distribution of Dosidicus gigas in different regions in the Eastern Pacific Ocean,the present study developed a habitat distribution model for this squid in summer and autumn in the equator,off Peru and Chile.The fisheries data in the equatorial waters of the Pacific Ocean,the waters off Peru from 2016-2018,and the waters off Chile from 2015-2017 were used and obtained from National distant-water fisheries data center of China.Seven marine environmental factors including Sea surface temperature(SST),Eddy kinetic energy(EKE),Sea surface salinity(SSS),Sea surface height(SSH),Chlorophyll concentration(Chl.a),Mixed layer depth(MLD),and Dissolved oxygen concentration(DO)were considered in this study.The maximum entropy model(MaxEnt)was applied to investigate the distribution of suitable habitat for Dosidicus gigas and the differences in the effects of the environmental factors on it were examined in different seasons in different waters.The results showed that the AUC values of the maximum entropy model were higher than 0.8 in different seasons in different areas,and the actual fishing locations coincided with the range of suitable habitats fitted by the model.The distribution of optimal habitats in the three regions was as follows:in the equatorial waters in summer,the optimal habitats were mainly distributed within the ranges of 110°W-120°W,1°N-3°S;in autumn,the optimal habitats for Dosidicus gigas were mainly distributed within the ranges of 97°W-117°W,1.5°N-1.5°S,and the distribution of suitable habitats was extended to the east from summer to autumn.In summer,the optimal habitats of Dosidicus gigas off Peru were mainly located in the range of 75°W-86°W,15°S-20°S;in autumn,the optimal habitats of Dosidicus gigas were mainly located in the range of 75°W-84°W,15°S-20°S,with the optimal habitats moving southeastward from summer to autumn.The optimal habitats of Dosidicus gigas in summer off Chile were mainly distributed in the range of 73°W-85°W,20°S-30°S;in autumn,the optimal habitatswere mainly distributed in the range of 75°W-85°W,20°S-28°S,and the overall suitable habitats moved to the northeast from summer to autumn.Based on the contribution rate of each environmental factor in the habitat model,SSH,Chl.a,SSS and SST were the important environmental factors affecting jumbo flying squid habitat in the equatorial waters;SSH,MLD,DO and SST were the important environmental factors affecting jumbo flying squid habitat in the offshore Peru,and SSH,SST,Chl.a and MLD were the important environmental factors affecting jumbo flying squid habitat in the offshore Chile.Our findings suggested that significant geographical difference was shown in the environmental factors affecting Dosidicus gigas distribution in different regions.