Determinação de idade da pescada gó (macrodon ancylodon) no estuário amazônico através da leitura de anéis em otólitos

Abstract

The hake (Macrodon ancylodon) is a marine demersal fish species from tropical and subtropical zones, which is distributed along the coast from Venezuela to Argentina. This species is widely exploited along the coast of Brazil, especially in the Rio Grande do Sul region. The objective of this work was to identify the age rings in otoliths and relate them with fish meristics and age. Collections were carried out in the Amazon estuary during the dry season of 1996, the rainy season, and the dry season of 1997, respectively. The collected specimens were placed in plastic bags, frozen aboard the fishing boat Marilu and taken to the laboratory. In the latter the identification of sex was made, the gonads and their maturity were examined, the total length (mm) and total weight (g) were measured and the otoliths (sagitta) were removed for age determination. The otoliths were placed in plastic mass, cut, fixed on slides and analyzed under a microscope. The parameters of weight and length relationship were not statistically different between sexes and relationship obtained was Weight=1 ,020.10 -6.L3726 (n=3335, r=0.99, P<0.01.) ). The relationship between otolith radius and body length were significantly different for the sexes, and for males it was: Length= 0.029951 +0.003195. Otolith Radius (n=161, r= 0.81, P<0.01). and for females Length= 0.130237+0.002564. Otolith Radius (n=150, r=0.85, P<0.01). Comparing the mean lengths by age groups between the sexes shows that females grow faster than males and that both sexes show by age groups, longer lengths in summer than in winter.