Biologia reprodutiva, idade e crescimento da pescada branca Cynoscion leiarchus (Actinopterygii, Sciaenidae) na Baía de Sepetiba, RJ

Abstract

The smooth weakfish Cynoscion leiarchus is a coastal species from the Sciaenidae family, with distribution from Panamá to Southern Brazilian coast, occurring mainly in estuarine waters near to muddy and sandy substrate. In the last decades, this species is ranking among important fisheries resources in Southeastern Brazil, however there are few available information on biological and populational dynamics of this species. In this study, we aimed to determine reproductive and growth parameters of this species and to compare with the available information to obtain basic information for this resource management, as well as to test the null hypothesis that these parameters do not differ from general pattern within the genera. A total of 370 individuals (190 females and 170 males), with total length ranging from 205 to 486 mm for females and 205 to 493 mm to males. Fishes were collected with gill nets (stretched mesh size 35; 45; 35 mm) used in artisanal fisheries in the Sepetiba Bay, between July 2013 and June 2014. This species showed spawning in batches, type of ovarian development synchronic of more than two groups, and indeterminate fecundity, characterizing a wide reproductive season peaking in spring/summer. Size at first maturation (C50) was 324mm for females and 270 mm for males, respectively. Readings of sections of age rings sagittae otoliths indicated that the growth curve of length versus age for females was Ct = 503*(1–e - 0.15*(t –0.27)) and for males was Ct = 470*(1–e -0.16*(t+0.04)). Longevity for females was 20 years and for males was 19 years, and natural mortality M = 0.15(year-1) for females and M = 0.16(year-1) for males. The marginal increment and percentage of edge pattern indicate periodicity of age rings is yearly, with ring formation in autumn. This study supply the first information on reproductive and size-at-age (growth) of this species in southeastern region, comprising an valuable contribution to formulate public policies to sustainable fisheries resources management of this species that have been exploited in the region.