基于精细尺度的冬季南乔治亚岛南极磷虾渔获率时空与环境效应

Spatial-temporal and environmental effects of catch rate on Antarctic krill fishery in the South Georgia Island in the austral winter season based on the fine scale data

南乔治亚岛水域不仅是南极磷虾渔业的主要渔场之一,同时该水域的南极磷虾也是许多以该岛为栖息地的捕食者（如海豹、鲸鱼等）的饵料,因此对该岛南极磷虾资源丰度的研究对于深入理解南极生态系统有着非常重要的作用.本研究基于精细尺度渔业数据,利用广义可加模型（GAM）对2013年冬季南极磷虾渔获率与环境因子之间的关系进行研究.结果表明：该模型对渔获率总偏差解释率为32.0%,其中贡献最大的为旬别,贡献率为21.4%;其次为纬度,但贡献率显著降低,仅为4.4%.7月上旬至9月上旬,渔获率总体上呈下降趋势.渔场东侧渔获率较高,尤其是中东部海域,而北侧的渔获率相对偏低.随着地形变化程度的增大,平均渔获率呈下降趋势.风力处于4级以下的情况不仅适宜捕捞作业,且渔获率也处于较高的水平.风向并不会对渔获率产生显著的影响.在表温0.5~2.0℃范围内,随着表温的增加,平均渔获率呈上升趋势.

The waters around the South Georgia Island is one of the main fishing ground of Antarctic krill fishery and many predators such as sea seal and whale inhabited this island target Antarctic krill as a food source. So it is very important for further understanding Antarctic ecosystem to con- duct the research on abundance fluctuation of Antarctic krill resource around this island. Conse- quently, based on the fine scale fishery data collected in the winter 2013, using the generalized ad- ditive model （GAM） , the present study analyzed the relationship between environmental factors and the catch rate of Antarctic krill. The results showed the model could explain 32.0% of the accumu- lation of deviance of the catch rate. The variable that provided the maximum contribution was ten-day with a contribution rate of 21.4% and followed by the latitude （4.4%）. Generally, the catch rate decreased from the first 10 days of July to September. Higher catch rates occurred in the eastern fish-ing ground, particularly the central-eastern part of survey area, and lower catch rates presented in the northern part. The mean eateh rate deceased with the increasing change rate of bathymetry. The oce- anographic condition with wind scale helow 4 was suitable for fishing operation and associated with the higher catch rate, but the wind direction did not significantly affect the catch rate. The mean catch rate increased with the increasing sea surface temperature within 0.5 to 2.0 ℃.