Growth and first sexual maturation size of <em>Salminus maxillosus</em> Valenciennes, 1849 (Characiformes, Characidae), in Mogi Guaçu river, state of São Paulo, Brazil

Abstract

Age and growth were estimated from counts of hyaline zones in scales of dourado, Salminus maxillosus Valenciennes, 1849, of Mogi-Guaçu River, state of São Paulo. The time of annuli formation was established by the scales’ marginal growth quotient variation. The first sexual maturation size was determined, and the reproductive period was defined by the analysis of the maturation curve, based on the gonadosomatic index variation, the relative frequency of the maturation stages and of the hepatosomatic index. Annulus formation is annual, occurring during the spawning period. The first annulus formation was observed in the second year of the fish life, corresponding to 346.7 mm and 447.4 mm for males and females, respectively. Up to seven annulus for males and eight for females were observed. The growth curve in length were adjusted by the mathematical expression of von Bertalanffy (1938) and the growth curve in weight by the deductive method from the expressions of the length growth curve and weight/length relationship. The L_∞ and W_∞ values were 874.0 mm and 8804 g for females and 713.0 mm and 4416.0 g for males. The growth rates were 0.3917 and 0.3572 for females and males, respectively