Population and fishery parameters of the thread herring (Opisthonema oglinum) of the northeastern coast of Brazil

The small, pelagic fish Opisthonema oglinum is a commercially important species that inhabits shallow coastal areas of the western Atlantic Ocean. Life-history and fishery data are scarce or date back several decades, especially for the northeastern coast of Brazil. In this study, estimates of the population and fishery parameters of the species were obtained for the coast of the state of Pernambuco. Length-frequency distribution data were obtained from monthly samples collected between 2014 and 2020, from which estimates of the von Bertalanffy growth model parameters, mortality rates, virtual population analysis (VPA), yield per recruit (Y/R) and spawning potential ratio (SPR) were derived. The asymptotic length and growth coefficient were 24.71 cm and 0.71 yr⁻¹ , respectively. The annual total (Z), natural (M) and fishing (F) mortality rates were 2.17, 1.11 and 1.06 yr⁻¹ , respectively. From 8.25 cm onward, F becomes higher than M for the local fishery. In the Y/R estimates, the values of F max = 1.30 yr⁻¹ , F0.1 = 1.10 yr⁻¹ and F0.5 = 0.50 yr⁻¹ indicated that exploitation operates at a level close to the optimal yield per recruit. However, SPR estimates ranging from 0.09 to 0.13 reveal a deficit of large individuals, necessitating cautious interpretation for 2019 and 2020 due to reduced sample sizes. The findings of this study provide support for the development of effective management strategies for the conservation of O. oglinum of the northeastern coast of Brazil.