2012—2018年中西太平洋延绳钓渔业大青鲨兼捕量影响因素分析  

Study on the factors influencing the bycatch of Prionace glauca in Western and Central Pacific longline fisheries from 2012 to 2018

作　　者：杨军勇 吴峰[2] 杜若谦 YANG Junyong;WU Feng;DU Ruoqian(Rongcheng Fisheries Technology Promotion Station,Rongcheng 264300,Shandong,China;College of Marine Sciences,Shanghai Ocean University,Shanghai 201306,China;Shandong Overseas Fisheries Associatic,Jinan 250000,Shandong,China)

机构地区：[1]荣成市渔业技术推广站,山东荣成264300 [2]上海海洋大学海洋科学学院,上海201306 [3]山东省远洋渔业协会,山东济南250000

出　　处：《上海海洋大学学报》2022年第3期691-699,共9页Journal of Shanghai Ocean University

基　　金：农业农村部远洋渔业管理技术支撑项目(2021-0056)。

摘　　要：大青鲨(Prionace glauca)是中西太平洋金枪鱼延绳钓渔业主要的兼捕物种,其兼捕量的估算是当前资源评估和管理的焦点问题。根据我国金枪鱼渔业国家观察员2012—2018年调查数据,利用Tweedie-GAM模型,分析了大青鲨单钩次兼捕量与时空因素、环境因素和作业因素的关系,并利用交叉验证对基于模型的方法与分层比率估计法对兼捕量估算的影响进行了比较分析。结果显示,模型累积解释率为51.6%;单筐钩数、经度和纬度是主要影响因素。单钩次兼捕量随着单筐钩数的增加波动降低,当单筐钩数大于19时,兼捕量显著降低;具有显著的纬向和经向递增的分布特征,在低纬度地区较低且分布均匀(10°S~5°N),东部水域高于西部;单钩次兼捕量季节差异不显著,受月光亮度影响,满月日作业的渔船兼捕量显著升高;在叶绿素浓度较高(≥0.15mg/m^(3))或暖温海域(≥29.5℃),兼捕量相对较高。同时,本研究发现单钩次大青鲨兼捕量与下钩数量的线性关系不显著;基于模型的兼捕量估计方法优于分层比率估计法。为降低大青鲨兼捕,建议中西太平洋延绳钓渔业单筐钩数不低于20,应控制在中纬度和178°E以东水域作业的渔船数量,并对其兼捕减缓措施的执行情况进行重点监测;为提高大青鲨或类似种群兼捕总量的估算精确度,后续研究建议采用基于模型的估算方法。Estimation of bycatch of the blue shark(Prionace glauca,BSH), a major bycatch shark in the Pacific tuna longline fishery, is a current focus of stock assessment and management. Based on the data collected during the 2012-2018 survey in the Pacific Ocean by national observers of tuna longline fisheries, the relationship between the bycatch of BSH and spatiotemporal, environmental, and operational variables was analyzed using the Tweedie-GAM model. The performances of the model-based approach and the stratified ratio estimation method on bycatch estimation were compared using cross-validation. The results showed that the number of hooks per basket(HBF), longitude, and latitude were the most influential variables, and the cumulative deviance explained by the optimal model was 51.6%. The bycatch fluctuated and decreased with the increase of HBF, and decreased significantly when HBF was more than 19. The spatial distribution of bycatch showed significant latitudinal and longitudinal increasing patterns, as it was lower and uniformly distributed in low latitude areas(10°S-5°N), and higher in eastern areas than in western areas. Regarding the temporal distribution, we found that the seasonal difference of bycatch was not significant, but the bycatch of fishing sets operating on a full moon day increased significantly due to the influence of moonlight brightness. Also, relatively high chlorophyll concentration(≥0.15 mg/m^(3)) or worm waters(≥29.5℃) was associated with high bycatch. There was no significant linear relationship between the bycatch and the number of hooks per set. The results demonstrated that the model-based bycatch estimation method was superior to the stratified ratio estimation method. To reduce the bycatch of BSH, it is recommended that the HBF of longline fisheries in the Western and Central Pacific should not be less than 20. The number of fishing vessels operating in the mid-latitudes and waters east of 178°E should be controlled, and their implementation of bycatch mitigation measures shou

关 键 词：大青鲨 兼捕量 Tweedie-GAM 金枪鱼延绳钓 

分 类 号：S932.4[农业科学—渔业资源]