Fisheries biology of a short-lived tropical species: Gerres longirostris (Lacépède, 1801) in the Arabian Gulf

The population dynamics and reproductive biology of Gerres longirostris were investigated in order to evaluate the impact of fishing on a relatively small, short-lived species with demographic attributes that contrast with other species that have been studied in the region. Well-defined alternating translucent and opaque bands in sagittal otoliths were validated as annuli and used to estimate age. Size-at-age relationships were highly asymptotic, most growth being achieved by the second year. Estimated maximum absolute age was 7.4 years. There were significant differences in the growth trajectories between sexes, females growing faster and to a larger maximum size than males. Spawning was between April and August, and the mean sizes and ages at first sexual maturity were 16.3 cm LF (1.1 years) for males and 20.6 cm LF (1.5 years) for females. The rate of fishing mortality (F = 0.32) approximated the optimum level (Fopt = 0.29), and was within the limit (Flimit = 0.38) biological reference point, indicating that the resource is exploited at an appropriate rate. Nevertheless, given that an independent assessment suggested that annual yields only represented 10% of the total biomass, it appears that even short-lived, fast-growing tropical species should have conservative harvest rates.