基于Tweedie-GAM模型的热带大西洋拟锥齿鲨单位捕捞努力量渔获量与环境因子的关系

拟锥齿鲨是热带大西洋金枪鱼延绳钓渔业中重要的兼捕物种,对其单位捕捞努力量渔获量(CPUE)与环境关系的研究可为该鱼种的资源保护和管理提供基础资料.根据我国金枪鱼渔业国家观察员2009—2015年在热带大西洋海域(6.38° S—14.92° N,42.03°—18.53° W)调查时采集的1085尾拟锥齿鲨数据及Tweedie类分布理论和特点,建立了GAM-Tweedie模型,对其CPUE的时间变化、空间分布及与环境因子的关系进行了分析.结果表明: 时空因子(年、月、经度、纬度)和环境因子对拟锥齿鲨名义CPUE的总偏差解释为40.2%,其中时空因子对其的影响均显著,环境因子中,海表面高度、叶绿素a浓度、作业时天气、海表面盐度、海表面气压对其影响显著,而海况、农历对其影响不显著;不同纬度和不同月份下海平面温度与拟锥齿鲨CPUE呈显著相关.2009—2015年拟锥齿鲨标准化CPUE呈现波动,整体呈上升趋势.

Relationship between the environmental factors and the CPUE (catch per unit effort) of Pseudocarcharias kamoharai in tropical Atlantic Ocean based on the GAM-Tweedie model

Crocodile shark (Pseudocarcharias kamoharai) is an important by-catch species of tropical Atlantic tuna longline fishery. The research on the relationship between the CPUE (catch per unit effort) and environmental factors can provide basic data for resource protection and management of this important species. Based on the Tweedie distribution theory, and the data of 1085 croco-dile sharks collected by the national observers of longline fishery from 2009 to 2015 in the tropical Atlantic Ocean (6.38° S-14.92° N, 42.03°-18.53° W), theGAM-Tweedie model was established, and the temporal and spatial effects of CPUE as well as the relationship with environmental factors were analyzed. The results showed the explained cumulative deviance of the crocodile shark’s CPUE to be 40.2%. The spatio-temporal factors (year, month, longitude, latitude) all hadsignificant effects (P<0.05) on the crocodile shark CPUE. The environmental factors such as sea surface height, chlorophyll a concentration, weather code, sea surface salinity and sea level pressure all had significant effects on CPUE (P<0.05). However, the Beaufort wind force and lunar calendar did not have significant effects on theCPUE (P>0.05). Significant correlation (P<0.05) was observed at different latitudes and in months between the sea surface temperature and CPUE. The standardized CPUE of the crocodile shark in 2009-2015 showed a fluctuating increase trend.