Accounting for the fish condition in assessing the reproductivity of a marine eel to achieve fishery sustainability

• Published in: Ecological indicators Vol. 130; p. 108116
• Main Authors: Mu, Xiuxia, Zhang, Chongliang, Xu, Binduo, Ji, Yupeng, Xue, Ying, Ren, Yiping
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2021; Elsevier
• Subjects: biomass; Body condition; body weight; Conger myriaster; eel; Fecundity; Harvest restriction; risk; SPR; Harvest restriction; SPR; Conger myriaster; Fecundity; Body condition
• ISSN: 1470-160X; 1872-7034
• DOI: 10.1016/j.ecolind.2021.108116

•Conger myriaster has length- and condition-driven reproductive strategies.•Fish condition greatly influences the estimates of SPR-related reference points.•Spawning stock biomass can produce 10–25% bias in calculating F40%.•Monitoring the changes in body conditions in fisheries assessment is needed. Spawning potential ratio (SPR) is a commonly used biological reference point to inform management decisions; however, the fish reproductivity may vary substantially with different body conditions, and the variability has not been well understood. Here, we examined the maturity, fecundity, and SPR of a marine eel Conger myriaster. The results showed that total fecundity increased with length and hepatosomatic indices (HSI), whereas relative fecundity (total fecundity/body weight) decreased with body weight, suggesting length- and condition-driven reproductive strategies. A length-structured per-recruit model was used to estimate SPR and examine the influence of HSI in resultant management decisions. Our results suggested that this stock was subject to a high risk of recruitment overfishing. Fish condition greatly influences the estimates of SPR-related reference points. For example, when HSI increased from 0.6% to 1.8%, F40% increased by 91%. In addition, using spawning stock biomass to calculate F40% could produce a bias of 23%. We highlight the need for monitoring the changes in fish fecundity and conditions in fisheries assessment, which may contribute to the robust management of data-poor fisheries.