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

Linlong Wang,Lu Zhai,Yang Liu,Shen Ye,Li Lin

doi:10.3389/fmars.2021.757503

Abstract

China has become the largest contributor to marine fisheries in the world with its fishing fleets explosively increasing their fishing effort and resulting catch, but its fishery composition and sustainability have deteriorated. Limited information on fishery exploitation status encumbers effective resource management. In this study, a data-poor Monte Carlo method, the Catch-Maximum Sustainable Yield (CMSY) method, was used to estimate the historical exploited dynamics and current stock status of ten Chinese economic marine fish stocks, includingTrichiurus lepturus,Larimichthys crocea,Larimichthys polyactis,Thamnaconus modestus,Scomberomorus niphonius,Ilisha elongate,Decapterus maruadsi,Scomber japonicus,Engraulis japonicus, andClupea pallasii, which accounted for about 50% of total fish catches in the coastal waters of China and covered five functional groups (i.e., large, medium benthopelagic, large, medium, and small pelagic). SpeciesL. croceaandL. polyactishad been subjected to overfishing since the 1950s. The others showed a decreasing trend in biomass along with the explosively increasing fishing efforts since the 1990s. Benthopelagic fish experienced overfishing pressure about a decade earlier than pelagic species. All the fish stocks investigated in this study were depleted (current biomass lower than the biomass capable of producing maximum sustainable yields, i.e.,B&lt;Bmsy) in 2019, and most species were still facing high-fishing pressure (current fishing mortality higher than the mortality capable of producing maximum sustainable yields, i.e.,F&gt;Fmsy). Also, a Schaefer model was used to assess stocks rebuilding status until 2030 under four exploitation scenarios, i.e., fishing mortality equals 0.5, 0.6, 0.8, or 0.95 timesFmsy. Most species stocks will likely recover to theBmsy, which indicates that reduction of fishing pressure is probably the most effective way for fishery recovery.

Highlights

Overfishing has altered structures of fish population (Zhang W. et al, 2019) and caused the continual decline of global fisheries (Link and Watson, 2019)
The model diagnostics and prior-posterior variance ratios for T. lepturus, L. crocea, I. elongate, and E. japonicus were selected as the surrogates of top predators, middle carnivores, omnivores, and plankton feeders, respectively, and shown in Supplementary Figures 1, 2
The historical exploitation dynamics of the ten species were presented as catches, relative biomass to the biomass capable of producing maximum sustainable yields (B/best maximum sustainable yields (Bmsy)), and relative fishing mortality to the mortality capable of producing maximum sustainable yields (F/fishing pressure that could produce MSY (Fmsy)) (Figure 1)

Summary

Introduction

Overfishing has altered structures of fish population (Zhang W. et al, 2019) and caused the continual decline of global fisheries (Link and Watson, 2019). The catch per unit effort (CPUE) in the Bohai Sea in 2011 (3.62 kg·haul−1·h−1) has dropped to 0.86% of that in 1959 (421.66 kg·haul−1·h−1) (Shan et al, 2013; Zhang W. et al, 2019), and the dominant species had been altered from the high-valued and large-sized species, e.g., largehead hairtail Trichiurus lepturus, to the species in lower trophic level, such as Scaly hairfin anchovy Setipinna taty and Japanese anchovy Engraulis japonicus. In the South China Sea, overfishing was the main driver that led to the biomass declination of fishery resources (Zhang W. et al, 2019) and even to the extinction of some coral reef fishes (Arai, 2015)

Methods

Results

Discussion

Conclusion