Idade e crescimento do robalo-flecha, Centropomus undecimalis (BLOCH, 1792) e do Robalo-Peva, Centropomus parallelus (POEY, 1860), no sudeste do Brasil

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Rio de Janeiro State, with total length ranges of 33.1–78.9 cm and 29.5–57.3 cm, respectively, from which scales were withdrawn for the identifi cation of age rings and measurement of growth bands, in the period from June, 1999 through June, 2000.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 coeffi cient (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 signifi 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 JanuaryMarch (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; t0 = - 2.59 yr.; tm = 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.; tm = 16.0 yr.; φ’ = 2.936; (d) the natural mortality coeffi cient 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.