Standardized catch rate of cockfish, Callorhinchus callorynchus, in a bottom trawl fishery of Patagonia: Is it possible its use as a predictor of abundance trend?

Abstract The catch per unit of effort (CPUE) data of cockfish, Callorhinchus callorynchus, during 1986-2011 was evaluated for the bottom trawl fishery of the San Matías gulf (Patagonia, Argentina). The objective of this work was to detect what are the factors related to fishery dynamic that affect catch rate of cockfish and to assess standardized CPUE by General linear models (GLMs) and General linear mixed models (GLMMs) as a relative abundance index. The annual trend of the catch rate indicated an increase during the evaluated period. The nominal CPUE and the indices standardized by the Delta-GLM and Delta-GLMM showed the same annual trend, with increases of 57%, 61.1% and 60.7%, respectively. The LogNormal models have the best-fit model and explained 23.5% of the total variability. The factors year, month, depth and hake CPUE explained the highest variability. The analysis of the models indicated that the catch rate of cockfish is subject to the lack of an homogeneous distribution of the fishing effort during different years, months and vessels. This was related to the fleet dynamic searching the targets species. The increasing trend of CPUE and landings would be indicating an increase in effort directionality to the cockfish in the last decade.

摘要 本研究针对阿根廷巴塔哥尼亚圣马蒂亚斯湾底拖网渔业1986至2011年间的银鲛（学名：Callorhinchus callorynchus）单位捕捞努力量渔获量（catch per unit of effort, CPUE）数据展开评估。本研究旨在明确影响银鲛捕捞率的渔业动态相关因子，并通过广义线性模型（General linear models, GLMs）与广义线性混合模型（General linear mixed models, GLMMs）构建标准化CPUE作为相对丰度指数。评估期内银鲛捕捞率的年度变化趋势呈上升态势，名义CPUE以及经德尔塔-GLM、德尔塔-GLMM标准化后的指数呈现一致的年度变化趋势，增幅分别为57%、61.1%与60.7%。对数正态模型为最优拟合模型，可解释总变异量的23.5%。年份、月份、水深以及无须鳕CPUE为解释变异量占比最高的因子。模型分析表明，银鲛捕捞率受捕捞努力量在不同年份、月份与作业渔船间分布不均的影响，这一现象与船队以目标物种为导向的作业动态密切相关。近十年来CPUE与渔获上岸量的上升趋势，表明针对银鲛的捕捞努力量方向性有所提升。