Population Dynamics of the Sebastes schlegelii Stock in Zhangzi Island’s Waters, China: Implications for Management and Conservation

Abstract

Sebastes schlegelii is a species of great economic significance in Zhangzi Island’s waters in the Northern Yellow Sea. Since the beginning of the 21^st century, there has been a significant decline in the fishery resources of Sebastes schlegelii, and the reduction in size has become increasingly apparent. Therefore, it is imperative to understand the characteristics of Sebastes schlegelii and develop management tactics. Based on biological data from Sebastes schlegelii collected in Zhangzi Island’s waters, an analysis was conducted on the relationship between body length and weight, growth equations were formulated, and an assessment was made of the resources’ status. The study simulated and evaluated the effects of various closed season management strategies on egg production per recruit (EPR) and spawning biomass per recruit (SBR). The results showed the following. (1) The length-weight relationship was W = 5 × 10⁻⁵L^2.882. (2) Von Bertalanffy’s growth equation was L_t = 450[1 − e^{−0.31(t+0.42)}] and W_t = 2215.8[1 − e^{−0.31(t+0.42)}]^2.882. (3) The resource is in an overfished state with an exploitation rate (E) of 0.737, a steady-state biomass of 1471 t, and a maximum sustainable yield of 466 t. (4) The closed season for Sebastes schlegelii in Zhangzi Island’s waters is suggested to be from November to February, coinciding with the recovery of the EPR value to 68.33% and the SBR value to 29.53%.