基于体长数据的舟山渔场小黄鱼资源评估

Length-based stock assessment of small yellow croaker (Larimichthyspolyactis) in the Zhoushan fishing ground

  • 摘要:
    目的 针对舟山渔场小黄鱼资源衰退且长期缺乏系统统计数据的问题,通过仅需短期体长调查数据的小黄鱼资源评估方法,明确其资源现状与开发水平,为该种群的科学管理与保护提供依据。
    方法 基于2019—2024年4个航次采集的772尾小黄鱼体长数据,使用ELEFAN方法估算生长参数(LinfK),采用6种经验公式估算自然死亡系数(M),并设置不同参数情景。综合基于长度的产卵潜力比法(LB-SPR)和基于长度的贝叶斯生物量分析法(LBB)进行评估,对输入参数进行敏感性分析,并结合两种方法的结果以评估资源状态。
    结果 LB-SPR结果显示,小黄鱼平均相对捕捞死亡率(F/M)为6.70,平均产卵潜力比(SPR)仅为0.05;LBB结果显示,平均F/M为9.97,平均相对资源量(B/BMSY)为0.09,平均开捕体长与最适开捕体长之比(Lс/Lс_opt)为0.70。参数敏感性分析表明,尽管评估结果受输入参数影响,但对资源状态的结论稳健。所有指标一致表明,舟山渔场小黄鱼种群所受捕捞压力极高,产卵潜力与生物量极低。
    结论 舟山渔场小黄鱼资源已遭受严重过度开发。本研究使用的资源评估方法与流程在数据有限情况下表现出良好的适用性与稳健性,为类似数据有限渔业的资源评估提供了方法参考。

     

    Abstract: Assessing the current stock status of the Larimichthys polyactis, a fish species of high ecological and economic value, in the Zhoushan Fishing Ground is crucial for ensuring the sustainable utilization of its resources. In response to the decline in L. polyactis resources and the long-term lack of systematic statistical data in the Zhoushan Fishing Ground, this study employs stock assessment methods that require only short-term length-frequency data to clarify the current stock status and exploitation level of this population, thereby providing a scientific basis for its management and conservation. Based on length data from 772 individuals collected during four surveys from 2019 to 2024, growth parameters (the asymptotic length, Linf, and the growth coefficient, K) were estimated using ELEFAN methods, while the natural mortality coefficient (M) was estimated using six empirical formulas. Different parameter combination scenarios were set up, applying both the Length-Based Spawning Potential Ratio (LB-SPR) and the Length-Based Bayesian Biomass (LBB) assessment methods. Sensitivity analyses were performed on input parameters, and results from both methods were integrated to evaluate stock status. The LB-SPR assessment indicated that the average relative fishing mortality (F/M) was 6.70, while the average spawning potential ratio (SPR) was only 0.05. The LBB assessment revealed that the average F/M was 9.97, the average relative biomass (B/BMSY) was 0.09, and the ratio of mean length at first capture to optimal length at first capture (Lc/Lc_opt) was 0.70. Sensitivity analyses demonstrated that while quantitative results varied with input parameters, the conclusion regarding the stock status remained robust. All indicators consistently showed that the L. polyactis stock in the Zhoushan fishing ground is subject to extremely high fishing pressure, with critically low spawning potential and biomass, alongside significant population miniaturization. The conclusion is that L. polyactis resource in the Zhoushan fishing ground has suffered severe overexploitation. And the stock assessment methods and procedure used in this study demonstrates strong applicability and robustness under data-limited conditions, providing a methodological reference for stock assessment research in similarly data-limited fisheries.

     

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