Stock Assessment of Small Yellow Croaker (Larimichthys polyactis) Off the Coast of China Using Per-Recruit Analysis Based on Bayesian Inference

Abstract

This paper presents a framework for quantifying uncertainty in per-recruit analysis for small yellow croaker (Larimichthys polyactis) fisheries in China, in which credible estimates of life history parameters from Bayesian inference were used to generate the distribution for a quantity of interest. Small yellow croakers were divided into five spatial groups. The status of each group was examined using a yield-per-recruit (YPR) model and a spawning stock biomass-per-recruit (SSBPR) model. The optimal length at first capture (Lcopt) was proposed to recover the biomass. The maximum observed age in the current stocks (3 years) and the maximum recorded age (≥20 years) were adopted in per-recruit analysis. Our results suggest that the framework can quantify uncertainty well in the output of per-recruit analysis for small yellow croaker. It is suited to other fish species. The SSBPR at FMSY (SSBPRMSY) is a better benchmark than the spawning potential ratio (SPR) at FMSY because SSBPRMSY had a unimodal distribution. The SSBPR analysis can lead to a more conservative Lcopt than the YPR analysis. The key factor influencing the assessment conclusions may be the growth parameters rather than the natural mortality rate for a stock with a younger maximum age. Overfishing likely occurred for all groups and recruitment overfishing may not occur if the maximum age is maintained at 3 years. Increasing lengths at first capture to the recommended values can help this population recover. However, Fcur is too high for small yellow croakers to attain the maximum recorded age. Both reducing fishing mortality rate and increasing length at first capture are needed to attain the maximum recorded age.

Evaluating Catch-Only Methods to Inform Fisheries Management in the East China Sea

“…For instance, the stock status of L. polyactis was estimated to be in the green quadrant of its Kobe plot (neither overfished nor overfishing occurred) across all years except for the initial year. Previous assessments using Bayesian statespace surplus production models indicated that L. polyactis was overfished and overfishing occurred since the 1980s (Ma et al, 2020), the conclusion of overfishing was also supported by recent per-recruit analysis (Zhu et al, 2021). Apart from L. polyactis, three other stocks (S. japonicus, S. niphonius, and T. lepturus) were also previously assessed by surplus production models (Li et al, 2010;Zhang et al, 2015;Sui et al, 2021).…”

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“…The first application of the data-limited approach to new species (e.g., Angelini et al, 2021;Falsone et al, 2021;Geraci et al, 2021;Shi et al, 2022;Tsikliras et al, 2021;Wang et al, 2021;Wang et al, 2022;Zhang et al, 2021;Zhang et al, 2022;Zhu et al, 2021).…”