Age, Growth and Mortality of the Jamaican Weakfish, Cynoscion jamaicensis (Vaillant & Bocourt 1883), in the Southeastern Brazilian Bight

Cynoscion jamaicensis is an important demersal species in the Southeastern Brazilian Bight (SEBB), yet information on its population dynamics in this region is limited and out of date. This study provides the first assessment of the species’ age, growth, and mortality in the SEBB, based on sectioned otoliths. The annual deposition of annuli was validated through relative marginal increment and edge analyses, and a refined age-assignment approach that incorporated birth date and capture month was employed. Growth was described using the von Bertalanffy growth model, yielding a maximum theoretical length (TL∞) of 278.49 mm and a growth coefficient (k) of 0.545 year−1. Total mortality was estimated at Z = 0.74 year−1, with natural mortality (M = 0.60 year−1) and fishing mortality (F = 0.14 year−1) indicating low-to-moderate exploitation (F/M < 1). The results suggest truncation of the size structure and a shift in growth parameters, which are consistent with the effects of long-term fishing, although current levels of exploitation do not indicate overfishing. These findings provide an updated biological baseline and emphasize the importance of incorporating population parameters into ecosystem-based fisheries management.