Stock Assessment Using Length-Based Bayesian Evaluation Method for Three Small Pelagic Species in the Northwest Pacific Ocean

Yuru He,Yongchuang Shi,Wei Fan,Xiaomin Zhang,Fenghua Tang

doi:10.3389/fmars.2022.775180

Abstract

Chub mackerel (Scomber japonicus), Pacific saury (Cololabis saira), and Pacific sardine (Sardinops sagax) are key economic and ecological species in the Northwest Pacific Ocean (NPO). In recent years, there have been some interannual changes in their catches due to the increasing number of fishing vessels and climate change. With the establishment of the North Pacific Fisheries Commission (NPFC) to better manage these three species, it is particularly important to develop an accurate understanding of the stock status of those fisheries resources. According to the production statistics of Chub mackerel, Pacific saury, and Pacific sardine in the NPO, the length-based Bayesian evaluation (LBB) method was adopted to conduct a stock assessment on the three fisheries in this study. Research results show that the asymptotic length of Chub mackerel in the NPOLinfis 37.54 cm, with the parameter ratios ofLc/Lc_opt= 1.10,F/M= 0.57,B/B0= 0.65, andB/BMSY= 1.10. The asymptotic length of Pacific saury in the NPOLinfis 33.24 cm, with the ratios ofLc/Lc_opt= 1.10,F/M= 0.14,B/B0= 0.82, andB/BMSY= 2.10. While the asymptotic length of Pacific sardineLinfis 39.33 cm, with the ratios ofLc/Lc_opt= 1.20,F/M= 0.20,B/B0= 0.77, andB/BMSY= 2.20. At present, the three species in the NPO are in a healthy state and have not yet been overfished. Body length bin may affect the estimation of some parameters without compromising the estimation of stock status. Our study indicates that the LBB model serves as an efficient method to evaluate the fisheries resources in the NPO, especially when length frequencies are the only available data. Hopefully, the results in this study can provide technical support for the conservation and management of Chub mackerel, Pacific saury, and Pacific sardine in the NPO.

Highlights

Chub mackerel (S. japonicus), Pacific saury (C. saira), and Pacific sardine (S. sagax) are the ecologically and commercially important species inhabiting the Northwest Pacific Ocean (NPO) (Tian et al, 2004; Yukami et al, 2009)
The estimate of fishing mortality (F/M) = 0.57 indicates that Chub mackerel fishery was not subject to increasing fishing pressure; the estimate parameters of B/B0 = 0.65, and B/BMSY = 1.10 confirm that the stock of Chub mackerel is in a good state in the NPO
The length-based Bayesian evaluation (LBB) model was recommended as a new supplement to the stock assessment approach for the data-limited stocks that have very limited or unreliable catch data (Kindong et al, 2020)

Summary

Introduction

Chub mackerel (S. japonicus), Pacific saury (C. saira), and Pacific sardine (S. sagax) are the ecologically and commercially important species inhabiting the Northwest Pacific Ocean (NPO) (Tian et al, 2004; Yukami et al, 2009). Since 2015, Chub mackerel and Pacific saury have been listed among the priority fish species by the North Pacific Fisheries Commission (NPFC), and the Pacific sardine is considered as one of the species to be managed in the future (North Pacific Fisheries Commission [NPFC], 2017). Due to their increasing commercial and ecological values, the research and management of these three small pelagic species in the NPO have gained much interest and concern in the field of fishery science (Arnold and Heppell, 2014)

Objectives

Methods

Results

Conclusion