Life history of Paralabrax callaensis (Starks, 1906) in Las Piñas Fishing Cove, Manabí, Ecuador

The southern rock bass (Paralabrax callaensis) is one of the main demersal species caught by artisanal fishers in Ecuador. However, local information on its life history is limited, prompting a study of its age, growth, and reproduction to provide data supporting the sustainable management of the species. A total of 162 specimens were collected from artisanal fisheries in Las Piñas fishing cove, Manta, Ecuador, between May 2018 and April 2019. Six age groups were identified based on the annual rings observed in otoliths (saggitae). The average total length (TL) of males was 32.1 ± 6.2 cm, while that of females was 33.7 ± 7.1 cm, L∞ = 67.59 ± 0.02 cm (95% CI) and K = 0.21 year-1 ± 0.01 (95% CI). The length-weight relationship showed a value of b = 2.94 for combined sexes, indicating an isometric growth pattern. Regarding reproduction, the sex ratio was 1.05M:1F, not differing significantly from the expected ratio. The gonadosomatic index (GSI) reached its highest values during transitional months, while the lowest values were observed during the dry season (June-November). The size and age at sexual maturity were estimated at L50 = 33.63 cm TL and A50 = 3.24 years for combined sexes. Results provide key biological information about P. callaensis, revealing its vulnerability due to its slow growth and late maturity.