Idade e crescimento da sardinha-verdadeira, Sardinella brasiliensis (Steindachner) (Osteichthyes:Clupeidae), no Sudeste do Brasil

Abstract

New estimates of the growth parameters of Brazilian sardinella, Sardinella brasiliensis (Steindachner), have been obtained, based on readings of age rings on scales collected in the period from April, 1999 through March, 2000, off southeastern Brazil. The hypothesis of the existence of isometry in fish/scale growth was confirmed and the ageing techniques were validated by monthly variations in the marginal increment and in the mean back-calculated length, indicating birthday dates in April and November. Two cohorts are supposed to be produced by spawnings taking place about six months apart. The weight-length relationship is given by the regression equation W = 0.0000867 L2.570. Growth equations in length (mm) and weight (g) are: Lt = 286 [1–e–0.462 (t + 1.3)] and Wt = 178.2 [1–e–0.462 (t + 1.3)]2.570, with a growth performance index φ’ = 4.58. The first ring in scales of Brazilian sardinella should be formed when individuals are actually 1.8 year old, within a life span that reaches tmax = 7.7 yr. The natural mortality coefficient was estimated as M = 0.769 and the ratio M/K = 1.66 is within the order of magnitude for Clupeidae species, being consistent with the behavior of small carnivorous species.