西北太平洋柔鱼栖息地适宜性变动研究

Habitat suitability variations of Ommastrephes bartramii in the Northwest Pacific

柔鱼(Ommastrephes bartramii)是西北太平洋重要的经济头足类,其栖息地受到气候变化的显著影响。根据中国鱿钓渔船在38°~45°N、140°~160°E作业渔场内的生产数据以及卫星遥感数据,利用信息增益技术选取关键环境因子,以单位捕捞努力量渔获量(CPUE)作为适应性指数,使用算术平均法(AM)和联乘法(GM)分别建立综合栖息地指数模型,对比异常环境条件下(厄尔尼诺和拉尼娜事件)柔鱼栖息地适宜性变动情况。结果表明,1998年La Ni■a事件发生时,西北太平洋传统作业渔场温度升高,海表温度(SST)相对正常年份2008年平均上升2. 72℃;而2009年El Ni■o事件发生时,SST相对正常年份降低0. 45℃。栖息地综合指数模型结果表明,1998年作业比重主要分布于在栖息地指数(HSI)大于0. 8的范围内,作业比重达到80%;2008年作业比重主要分布在HSI值0. 6~0. 8和0. 8~1. 0之间,所占比重在30%~50%左右; 2009年作业比重主要分布在HSI值0. 4~0. 6、0. 6~0. 8和0. 8~1. 0之间,作业比重平均约为32%。此外HSI值低于0. 2的区间面积随着La Ni■a事件、正常年份和El Ni■o事件递增,而HSI值大于0. 4的区间面积随着La Ni■a事件、正常年份和El Ni■o事件递减。研究认为,1998年La Ni■a事件发生时西北太平洋海域柔鱼适宜栖息地面积增加,而2009年El Ni■o事件发生时柔鱼栖息地适宜性变差,导致柔鱼产量变低。

The neon flying squid Ommastrephes bartramii is an economically important squid species widely distributed in the North Pacific. Its’ habitat is significantly affected by climate variability. In this study,we developed a habitat suitability index( HSI) model to evaluate variations in the habitat suitability of O.bartramii based on the arithmetic mean model( AM) and the geometric mean model( GM). Fishery data from the Chinese squid-jigging fishing vessels in the traditional fishing area between 38°-45°N and 140°-160°E from July to November in 1998,2008 and 2009 were used,as well as the key environmental factors selected from sea surface temperature( SST),sea surface height( SSH),sea surface salinity( SSS) and chlorophylla concentrations( Chl-a) through the information gain method. The results showed that the average SST from July to November in 1998 increased by 2. 72 ℃ under the La Ni■a condition compared with that in normal climate condition in 2008 in the traditional fishing ground; while the average SST in 2009 under the El Ni■o condition decreased by 0. 45 ℃ compared with that in the normal year of 2008. The HSI model suggested that the fishing efforts were mainly distributed in the waters with the HSI value higher than 0. 8 in 1998,with the value about 80%; in 2008,the fishing efforts were mainly distributed in the waters with the HSI value from0. 6 to 0. 8 and from 0. 8 to 1. 0,the value was between 30% and 50%; in 2009,the fishing efforts were primarily distributed in the waters with the HSI value from 0. 4 to 0. 8,0. 6 to 0. 8 and from 0. 8 to 1. 0,with an average of about 32% in the three grouped HSI values. Furthermore,the area with the HSI value < 0. 2 under the La Ni■a,normal and El Ni■o conditions gradually increased. However,the area with the HSI value> 0. 4 under the La Ni■a,normal and El Ni■o conditions gradually decreased. These findings suggested that the suitable habitat for O. bartramii enlarged in the La Ni■a year of 1998 in the fishing grounds of the Northwest Pacific. Whereas an El Ni■o event would lead to unfavorable environmental conditions and lowquality habitat,resulting in decreased catches of O. bartramii.