Biological and Ecological Aspects Regarding Cynoscion nothus Holbrook, 1855 (Perciforms: Sciaenidae)

A whole amount of 634 individuals pertaining to the species Cynoscion nothus, was caught in Las Barrancas beach, Veracruz (Alvarado Municipality), Mexico. Sampling were made over an annual cycle that included climatic characteristics of the region (Dry, windy and rainy seasons). The biggest amount of individuals was captured during the dry season (258), this amount was followed by 200 (windys season) and 176 individuals (rainy season) respectively. This study was conducted in order to determine some biological and ecological parameters of this species. W e determined the Seasonal W eight- Length relationship according to the equation proposed by Le Creen. It was observed that growth is allometric. The condition factor was estimated considering Fulton proposal, being this 3.56 for the windys season, 3.22 for the dry season, while the condition factor for the rainy season was 3.29. In the case of windy and rainy seasons we found five size classes and for the dry season, we found four size classes, according to the reading scale rings. The adjustment to the von Bertalanffy growth method showed that values achieved for the windys season, were Lmax. 36.30 cm and k = 0.1399. In the case of rainy season, Lmax was 35.53 cm and k = 0.2020. The sex ratio favored the males, lightly, being this 1:1:10 female- male through our work. The sex ratio according seasonal ratio, was as follows: 1:1.25 and 1:1.10 for the windys season and the dry season respectively, as well as the ratio in the rainy season favored the females (1.08: 1). Regarding gonadic maturity we found that during the windys season stages II, III, IV and V were present, and stages IV and V were predominant. In the case of the dry season, stages I, II, III, IV, V were identified, being the most frequent stages II and III and in the case of rainy season, predominant stages were II and III.