东太平洋延绳钓渔业兼捕鲨鱼物种的生态风险评估

Ecological risk assessment of shark bycatch in longline fisheries in Eastern Pacific Ocean

  • 摘要: 东太平洋是全球金枪鱼渔业的主要作业海域,其延绳钓渔业对兼捕鲨鱼种群的影响一直受到国际社会的高度关注。基于生产力-易损性分析 (Productivity-susceptibility analysis, PSA) 方法,对东太平洋延绳钓渔业兼捕的8种鲨鱼进行生态风险评估,并对PSA所采用的属性进行敏感性分析。结果显示:鲨鱼种群的生产力指数介于1.40~2.20,最高为黑边鳍真鲨 (Carcharhinus limbatus);易损性指数介于2.17~2.83,最高为尖吻鲭鲨 (Isurus oxyrinchus);脆弱性分数介于1.55~2.31,最高为大眼长尾鲨 (Alopias superciliosus)。生态风险评估表明,长鳍真鲨 (C. longimanus)、尖吻鲭鲨和大眼长尾鲨处于高风险状态,黑边鳍真鲨、镰状真鲨 (C. falciformis)、大青鲨 (Prionace glauca)、长鳍鲭鲨 (I. paucus) 和路氏双髻鲨 (Sphyrna lewini) 处于中风险状态。此外,敏感性分析结果显示,繁殖策略、种群水平重叠度和集群行为这3个属性对种群脆弱性评价结果影响最大,其移除后的均方根误差值 (Root mean squared error, RMSE) 分别为0.210 1、0.128 8和0.090 1。综上,长鳍真鲨、尖吻鲭鲨和大眼长尾鲨为东太平洋海域需优先关注的物种,建议加强数据收集、种群评估及管理措施,以降低渔业活动对其种群的影响。

     

    Abstract: The Eastern Pacific Ocean (EPO) is the main operating area for global tuna fisheries, and the impact of tunafishing in EPO on bycatch shark populations has always been highly concerned by the international community. Based on the productivity vulnerability analysis (PSA), we conducted an ecological risk assessment on eight shark species caught in the East Pacific longline fishing industry, and performed a sensitivity analysis on the attributes used in PSA. The results show that the productivity index ranged from 1.40 to 2.20, the highest being blacktip shark (Carcharhinus limbatus). The susceptibility index ranged from 2.17 to 2.83, the highest being shortfin mako shark (Isurus oxyrinchus). The vulnerability score ranged from 1.55 to 2.31, the highest being bigeye thresher shark (Alopias superciliosus). Ecological risk assessments indicate that oceanic whitetip shark (C. longimanus), shortfin mako shark and bigeye thresher shark were at a high risk, while blacktip shark, silky shark (C. falciformis), blue shark (Prionace glauca), longfin mako (I. paucus) and scalloped hammerhead (Sphyrna lewini) were at a medium risk. The results of sensitivity analysis indicate that reproductive strategy, areal overlap and aggregation behavior had the greatest influences on the species vulnerability scores, with Root Mean Squared Error (RMSE) values being 0.210 1, 0.128 8 and 0.090 1, respectively. To sum up, C. longimanus, I. oxyrinchus and A. superciliosus are the priority species in the EPO for further data collection, assessment and management, so as to reduce the impact of fishing activities on their population.

     

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