Age, growth and mortality of southern rays bream Brama australis (Bramidae) off the southeastern Pacific coast

Abstract

The age and growth function and mortality were determined for southern rays bream Brama australis caught in commercial trawls off the coast of central Chile. The results show that this species grows quickly in the first year and reaches the maximum asymptotic length (59 cm) at approximately 8 or 9 years old. The von Bertalanffy growth function described B. australis growth satisfactorily with length-at-age determined using otolith analysis. Parameters for the entire population (males and females) were: for length, L-infinity = 58.95 cm, K = 0.277 yr(-1), t(0) = -0.371 yr; and for weight, W-infinity = 2508.8 g, K = 0.257 yr(-1), t(0) = -0.712 yr. No differences were found in length-at-age between sexes. Estimates of total mortality rates (Z) from maximum age and catch-curve analyses were relatively high (0.9 year(-1)). The natural mortality rate (M = 0.45 yr(-1)) is consistent with the life parameters of middle-sized pelagic fish with relatively low exploitation at the time of sampling.