Assessments of 16 Exploited Fish Stocks in Chinese Waters Using the CMSY and BSM Methods

Abstract

Sixteen marine fish species (populations) exploited by Chinese fisheries were assessed, using published time series of catch and the CMSY and BSM methods. Given the catch times series as inputs, some ancillary information and reasonable constraints, carrying capacity, maximum sustainable yield, and likely time series of biomass and exploitation rate were estimated. The results show that one (7%) of the assessed species was severely depleted, four species (27%) were fully/overfished, six (40%) were outside of safe biological limits, one species (7%) was recovering and three species (20%) were in a healthy state at the end year of their assessment. However, one species, Pacific sardine (Sardinops sagax), could not be assessed using CMSY, as the exceedingly large fluctuations of its biomass were mainly environmentally driven. These results correspond with previous knowledge on the status of fish populations along the coast of China, where overfishing is rampant. Based on these assessments, some of the benefits that would result from a reduction of the excessive fishing effort are outlined.

Fishery Dynamics, Status, and Rebuilding Based on Catch-Only Data in Coastal Waters of China

“…This corroborates the results proposed in other regional stock assessments or fishery surveys in coastal waters of China (Zhang K. et al, 2017;Zhang C. et al, 2019;. For example, Zhai and Pauly (2019) and Zhai et al (2020) proposed that S. niphonius was grossly overfished (B 2013 /B msy = 0.48) in the East China Sea in 2013, and L. polyactis and E. japonicus were grossly overfished (B 2018 /B msy = 0.42) and overfished (B 2018 /B msy = 0.71) in 2018, respectively. In the coastal waters of China, the status for the D. maruadsi and S. japonicus was evaluated as slightly overfished (B 2014 /B msy = 0.83) and overfished (B 2017 /B msy = 0.70) in 2014 and 2017, respectively .…”

Long-Term Variability of Piscivorous Fish in China Seas Under Climate Change With Implication for Fisheries Management

“…The OCOM is useful to estimate management quantities across a range of stocks simultaneously when only catch data are available and when the average or ensemble statistics become more important (Zhou et al, 2018). Recently, biomasses of some piscivorous fish have been estimated by using the Monte Carlo method CMSY (catch-maximum sustainable yield) (Liang et al, 2020;Zhai et al, 2020). Comparisons between our biomass estimates and those based on CMSY showed similar variation patterns.…”

Response: Commentary: Stock Status Assessments for 12 Exploited Fishery Species in the Tsushima Warm Current Region, Southwest Japan and East China, Using the CMSY and BSM Methods

“…(Wang et al, 2020) mentioned that "the CMSY and BSM method is not appropriate for stocks that are affected by environmental factors that might lead to a regime shift that have the tendency to change a stock's population structure and thus, the evolution of its biomass". Zhai et al (2020) indicated that "As the 2-parameter CMSY model cannot readily accommodate massive changes in biomass due to environmental fluctuations, Pacific sardine treated as if it was overfished in 1950-1975" and "However, we did not report on its 'MSY' or other statistics, which would be unrealistic" in their study. We thus reiterate here that the CMSY and BSM models need to take such conditions into consideration.…”