Aspectos reprodutivos de plagioscion squamosissimus (teleostei, sciaenidae) mantidos em tanque rede na comunidade do Lago do Catalão, Amazônia Central

Abstract

Plagioscion squamosissimus kept in cages did not complete the final maturation of oocytes, having to be induced to make the process happen. The reproductive inducers used were gonadotropin-releasing hormone (GnRH - Ovaprim ®) and human chorionic gonadotropin (hCG). In females, it was observed that the yolk globules and oil droplets were present in the oocytes fusion process end after 12 hours of induction using 1.4 ml/kg body weight of Ovaprim®. With 300 IU of hCG/kg was observed the onset of melting at 12 h. The males didn’t show fully developed gonads in both experiments, and no significant difference between treatments was found. The gonads of males develop in sync with the sonic muscle and P. squamosissimus produces longer sounds when is ripe. The sounds or "calls" may indicate the state of maturity of males in the natural habitat that occurred during the dry season, which were detected "calls" of longer duration (0.404 ±0.191 sec.). Therefore, major number of pulses (20.7 ±9.7 pulses/call) than flood season (0.152 ±0.056 sec. and 8.4 ±0.8 pulses/called respectively).The sounds recorded in cages during the dry season had shorter duration than the sounds captured in the wild, perhaps indicating that individuals in cages are in a maturation process. The methods of cannulation used in females and the bioacoustics of males were effective for assessing the maturity of freshwater white Croaker. The passive acoustic method allows predict the time and place of spawning of this species and when males are ready to spawn.