不同气候模态下秘鲁外海茎柔鱼栖息地的季节性分布

茎柔鱼（Dosidicus gigas）为环境敏感型头足类，气候的多元变化促使茎柔鱼栖息地发生变动。本研究利用海表温度（SST）和海表面高度（SSHA）两个关键环境因子构建栖息地适宜性指数（HSI）模型，结合太平洋年代际涛动（PDO）指数，分析1950-2015年不同气候模态下秘鲁外海茎柔鱼栖息地的季节性分布规律。结果发现，PDO冷期茎柔鱼栖息地适宜性较高；而PDO暖期栖息地适宜性较低。相较于PDO冷期，PDO暖期下茎柔鱼适宜栖息地分布向东南移动。适宜栖息地的分布位置与适宜的SST和SSHA的重叠区域重合，表明两个关键环境因子与栖息地分布显著相关。此外，适宜栖息地指数距平值与PDO指数的年际变化呈显著负相关关系。春季茎柔鱼渔场栖息地适宜性高于冬季，且冬季适宜栖息地的分布相较春季偏东南方向。茎柔鱼渔场6-11月适宜的SST和最适宜的SST在经度和纬度上的分布存在显著差异，春季（9-11月）最适宜的SST分布逐月向西北方向移动；冬季（6-8月）最适宜的SST分布逐月向东南方向移动。推测不同气候模态下茎柔鱼栖息地季节性分布差异，可能是由于最适宜的SST显著的月间分布差异所致。研究表明，不同PDO时期下茎柔鱼栖息地适宜性具有显著季节性差异，其差异可由环境因子的月间变动来解释。

Seasonal habitat variation of jumbo flying squid Dosidicus gigas off Peru under different climate conditions

The jumbo flying squid Dosidicus gigas is an environmentally sensitive cephalopod. The habitat variation of D. gigas is greatly affected by multi-scale climate variability. In this study, we constructed a habitat suitability index (HSI) model based on two critical environmental variables (sea surface temperature (SST) and sea surface height (SSHA) from 1950 to 2015), and analyzed seasonal habitat distribution for D. gigas off Peru under different climate conditions. The results suggested that habitat suitability during the cold Pacific Decadal Oscillation (PDO) was higher than that during the warm PDO. Compared with the cold PDO, suitable D. gigas habitat during the warm PDO shifted southeastward. The spatial distribution of suitable habitat was consistent with the overlapping areas of both the suitable SST and SSHA ranges, indicating that the two critical environmental variables were significantly related to the spatial distribution of suitable habitats. Moreover, the HSI anomalies on the D. gigas fishing ground were significantly negatively correlated with the PDO index. The habitat suitability on the D. gigas fishing ground in spring was higher than that in winter, and the spatial distribution of suitable habitat in winter was further Southeast than that in spring. The longitudinal and latitudinal distribution of suitable SST and the most suitable SST on the fishing ground of D. gigas showed significant variability between June and November. The distribution of the most suitable SST in spring (September to November) shifted northwestward; however, the distribution of the most suitable SST in winter (June to August) shifted southeastward. The difference in seasonal habitat distribution for D. gigas under different climate conditions may be owing to the monthly difference in distribution of the most suitable SST. Our findings indicated that there were significant differences in the habitat suitability on D. gigas fishing grounds under different PDO periods, and the difference in seasonal distribution could be explained by monthly differences in environmental variables.