Abstract
The Beibu Gulf in China is rich in fish resources. However, only a small number of commercially developed fish stocks have been specifically assessed owing to limited data and expertise. In this study, 19 perciform fish populations in the Beibu Gulf were assessed using a length-based Bayesian biomass (LBB) estimator method, which is a new approach to evaluate a fishery’s status using length frequency (LF) data. The results showed that only 21% of the evaluated stocks were healthy and 79% were overfished. In particular, 26 and 21% of the assessed species had collapsed and were grossly overfished, respectively. Only 11 and 21% of the assessed species were slightly overfished and overfished, respectively. The ratios between the mean and optimum length (Lmean/Lopt) and between the mean length at first capture and the mean length, which maximizes catch and biomass (Lc/Lc_opt), were below one in 14 out of the 19 stocks, suggesting a truncated length structure and fishing of undersized individuals. The ratio of the 95th percentile length to asymptotic length L95th/Linf was close to one (>0.9) in 10 of 19 stocks, suggesting that at least some large fish were still present. Our research confirmed that the fishery resources in the Beibu Gulf were seriously overfished and provided evidence that LBB was an efficient method to evaluate the fishery resources. Fishery managers need to take specific measures to restore fishery resources.
Highlights
World fisheries, including freshwater, marine, and capture fisheries, as well as aquaculture, provide approximately 17% of the total animal protein consumed by humans, and around 56.6 million people are directly engaged in fisheries (Kang et al, 2018)
Wang X. et al (2020) evaluated the stock resources in Beibu Gulf from 2006 to 2018 by the length-based Bayesian biomass (LBB) method, and the results showed that the resources were overfished, especially in 2010 and 2011, which is consistent with our evaluation
The advantages of the LBB model are as follows: (1) the results of relative biomass or stock state have been verified by simulation and actual stocks; (2) there is no significant difference between the predicted LBB and the simulated B/B0; (3) the prediction of stock status by LBB is similar to that of other models; (4) LBB makes a preliminary estimation of the status of the fish group according to the length frequency (LF) data of the fishery; and (5) the results of LBB provide objective B/B0 priors for other evaluation methods such as CMSY and AMSY (Froese et al, 2017, 2018)
Summary
World fisheries, including freshwater, marine, and capture fisheries, as well as aquaculture, provide approximately 17% of the total animal protein consumed by humans, and around 56.6 million people are directly engaged in fisheries (Kang et al, 2018). After decades of rapid development, China has become the largest contributor to global marine fishing (FAO, 2019). China’s marine catch exceeds 15 million tons (Wang Y. et al, 2020). Since the 1970s, many of China’s marine fishery resources have been over exploited and the structure of the fish community has greatly changed (Kang et al, 2018; Zhang et al, 2020); the catches of some traditionally. Approximately 12% of the global fisheries are properly managed through stock assessments results (Kindong et al, 2020). Stock assessment is essential for the management of fisheries resources
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