库克群岛海域海洋环境因子对沙氏刺鲅兼捕率的影响

为了减少沙氏刺鲅(Acanthocybium solandri)的兼捕率,文章利用2012年9月~2012年11月在南太平洋库克群岛海域延绳钓渔业调查数据(包括钓钩深度数据,温度、盐度和叶绿素a质量浓度垂直剖面数据,作业参数和渔获统计数据),采用逐步回归的方法建立钓钩预测深度计算模型,利用统计和聚类分析的方法分析沙氏刺鲅的兼捕率与水层和温度的关系,并根据沙氏刺鲅兼捕率最高的水层推断得出其兼捕率最高的盐度和叶绿素a质量浓度范围。结果表明,库克群岛附近海域沙氏刺鲅兼捕率最高的水层和温度分别为40.0~80.0 m和26.0~28.0℃,推断得出沙氏刺鲅兼捕率最高的盐度段为36.30~36.90,叶绿素a质量浓度为0.070~0.243μg·L~(-1)。建议把钓钩深度设置到80 m以深、水温低于26℃、盐度高于36.90、叶绿素a质量浓度高于0.243μg·L~(-1)以减少延绳钓渔业中沙氏刺鲅的兼捕率。

Effects of environmental variables on bycatch rate of Acanthocybium solandri in waters near Cook Islands

To reduce the bycatch rate of wahoo (Acanthocybium solandri),we collected the data (hook depth,temperature,salinity and chlorophyll-a concentration vertical profile,operating parameters and bycatch) by longlining surveys in waters near Cook Islands from September,2012 to November,2012. Stepwise regression was used to develop the hook depth calculation model. Statistics and clustering analysis were used to analyze the effects of depth and temperature on wahoo bycatch rate. The salinity and chlorophyll-a concentration range with high bycatch rate of wahoo was obtained based on the depth range with high bycatch rate of wahoo. Results show that the depth and temperature range with high bycatch rate for wahoo were 40.0~80.0 m and 26.0~28.0 ℃,respectively. The deduced salinity and chlorophyll-a concentration range with high bycatch rate of wahoo were 36.30~36.90 and 0.070~0.243 μg·L-1,respectively. Results suggest that the hook should be deployed at the depth deeper than 80 m,temperature lower than 26 ℃,salinity higher than 36.90 and chlorophyll-a concentration higher than 0.243 μg·L-1,to mitigate the bycatch of wahoo when fishing in waters near Cook Islands.