基于渔获量调查数据的南海北部金线鱼捕捞限额评估

Quota assessment of Nemipterus virgatus in the Northern South China Sea Based on Catch Survey Data

  • 摘要:
    目的 了解南海北部现阶段金线鱼资源的利用状况,评估其最大可持续产量与捕捞限额。
    方法 应用CMSY++模型方法对由渔港抽样调查资料整理的金线鱼渔获量时间序列和16个单位捕捞努力量渔获量(CPUE)数据开展剩余产量模型拟合分析,估算环境承载量、内禀增长率、可捕系数以及最大可持续产量等种群参数;通过残差分析,检验CPUE数据的适用性。选择代表性的CPUE数据,运用B/BMSY、F/FMSY曲线比较不同渔业的金线鱼利用状况,并用Kobe图评估2023年时的种群状态。
    结果 南海北部金线鱼种群的环境承载力为70.45~81.72万t,内禀增长率为0.79~0.89,可捕系数为0.03×10−3~2.63×10−3,最大可持续产量为15.12~16.47万t;通过残差游程检验和残差异常诊断,发现有3个CPUE数据不适合CMSY++深度分析;代表拖网、刺网、钓具渔业的三组B/BMSYF/FMSY曲线在2008—2018年走势相似。代表刺网的B/BMSY曲线从2019年开始回升,至2022年升至1.0以上,F/FMSY曲线在2019年后降幅较大,低至1.0以下;而拖网与钓具的B/BMSY曲线在2019后未出现回增,F/FMSY曲线亦维持在1.0以上。Kobe图的风险概率显示,2023年时的金线鱼种群发生过度捕捞。
    结论 建议现阶段的南海北部金线鱼可捕量限额为13.2万t。基于渔获量调查的统计分析能从多个角度了解种群利用状况,设计并长期执行一个完善的渔获量调查方案,由此获得的精准渔业生产数据,将有助于复合渔业的资源评估与管理。

     

    Abstract: The allowable catch of Nemipteridae family in the northern South China Sea has been assessed, but management parameters for specific species are lacking. It is necessary to conduct a quota evaluation of Nemipterus virgatus to obtain more practical reference points for output control. Applying the CMSY++ approach, we analyzed the catch time series of N. virgatus reconstructed from stratified sampling survey data together with sixteen catch-per-unit-effort time series (CPUE). CMSY and BSM models were run to estimate biological reference points such as carrying capacity k, resilience r, catchability coefficient q, and maximum sustainable yield (MSY). Residual analysis was conducted to verify the applicability of CPUE datasets. Representative CPUE datasets were selected, the exploitation status of N. virgatus across different fishing methods was compared based on the trends of B/BMSY and F/FMSY, and the overall exploitation status of N. virgatus in 2023 was evaluated using the Kobe plot. The resilience r of N. virgatus in the northern South China Sea was estimated at 0.79~0.89, carrying capacity k at 704.47-817.20 thousand tons, the catchability coefficient at 0.03×10-3-2.63×10-3, and MSY at 151.66-164.71 thousand tons. Three CPUE datasets were identified as unsuitable for CMSY++ analysis through runs test of residuals and outlier diagnosis of residuals. For Three B/BMSY and F/FMSY trajectories were similar from 2008 to 2018 that represented trawl, gillnet, and longline fisheries respectively. The B/BMSY curve for gillnets began to recover in 2019 and rose above the safe level of 1.0 by 2022, whereas the corresponding curves for the other two gear types remained below 1.0. The F/FMSY for gillnets dropped markedly after 2019 and fell below 1.0, while the F/FMSY ratios for the other two gear types stayed above 1.0. Based on the risk probability indicated by the Kobe plot, the N. virgatus stock was considered to be overfished in 2023. A total allowable catch (TAC) of 132 thousand tons is recommended for the current stage. Statistical analysis based on catch surveys enables the understanding of stock exploitation status from multiple perspectives, and the design and long-term implementation of a sound catch survey program, along with the acquisition of accurate fishery production data derived therefrom, will contribute to the stock assessment and management of mixed fisheries.

     

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