ASPECTOS DA BIOLOGIA REPRODUTIVA DE SEIS ESPÉCIES DE PEIXES DE IMPORTÂNCIA COMERCIAL DO MÉDIO RIO XINGU – BASES PARA SEU MANEJO

Mauricio Camargo, Walmir Mário Alves Lima Júnior

Abstract


The spawning season and the mean length at first reproduction (L50) of Cichla melaniae, Prochilodus nigricans, Plagioscion squamossisimus, P. magdalenae, Myleus torquatus and M. pacu were studied. Seven field collections were made along one year. The captures were carried out with the use of gill nets. The weight and the total length of all the specimens caught were assessed. The sex and the development phase of gonads were established based in a macroscopic scale of four stages. The main season of reproduction was defined and compared with the seasonality of the flood pulses. The tucunaré (Cichla melaniae) and the curimatã (Prochilodus nigricans) showed synchronic spawns at the beginning of the flood season. Other species, such as the pacus (M. torquatus and M. pacu), although presenting a synchronic spawning strategy, also showed another pick of spawning activity during the dry season. The pescada P. squamossisimus, presented assinchronic spawning behavior along the whole year. The mean lengths at the beginning of the sexual maturation were: 26,45 cm for Cichla melaniae; 24,96 cm for P. squamossisimus; 22,25 cm for P. magdalenae; 23,08 cm for P. nigricans; 16,18 cm for M. torquatus; and 16,89 cm for M. pacu. Comparing these results with the landing volume, indicate that M. torquatus and M. pacu are captured in lengths far bellow (12-14 cm) the calculated L50. The closed seasons of this fishery not always coincide with the spawning season of pacus (Myleus). We suggest the establishment of minimum sizes of capture, based in the L50 calculated for each one of the studied species.

Keywords


Período de desova; Tamanho médio de inicio da maduração sexual; Peixes amazônicos; Rio Xingu; Tamanho mínimo de captura; Período de defeso; Spawn season; Mean length of the first sexual reproduction; Xingu River; Minimum length of capture



DOI: https://doi.org/10.31420/uakari.v3i1.20