Α ge and growth of common snook, Centropomus undecimalis (Bloch, 1792) and fat snook, Centropomus parellelus (Poey, 1860), off Southeastern Brazil

Abstract

This research work was designed to study age and growth of the common snook,  Centropomus undecimalis , and the fat snook,  Centropomus parallelus, off Southeastern Brazil. The database consists of 264 individuals landed at Niterói, Rio de Janeiro Sta te, with total length  ranges of 33.1–78.9 cm and 29.5–57.3 cm, respectively, from which scales were withdrawn for the identification of age rings and measurement of  growth bands, in the period from June, 1999 through June, 2000. In addition to the age and growth parameters, the natural mortality coefficient  (M) was also estimated in order to make up the M/K ratio. Statistical analyses were used in order to compare the growth pattern rate between  the two species, through Student’s  t test, and to assess the signi fi cance of the monthly marginal increment through Kruskal-Wallis’  H test and  Dunn’s  Q test. The drawn results may be summarized as follows: (a) the “birth date” of common snook and fat snook correspond with January- March (common snook) and June-August monthly periods; (b) age and growth parameters for common snook were: L ∞ = 101. 1 cm; W ∞ = 11.5  kg; K = 0.112; t 0 = - 2.59 yr.; t m = 26.7 yr.;  φ ’ = 3.058; (c) age and growth parameters for fat snook were: L ∞ = 67.9; W ∞ = 3.6 kg; K = 0.187;  t 0 = - 2.48 yr.; t m = 16.0 yr.;  φ ’ = 2.936; (d) the natural mortality coefficient was estimated at M = 0.259 ( C. undecimalis ) and M = 0.406  ( C. parallelus ), entailing values of M/K = 2.312 and M/K = 2.171, which classify those species into the fourth trophic level; (e) the growth  performance indices indicate the adoption of a strategy consistent with that assumed by medium-sized predatory species.