Factors affecting the distribution and abundance of freshwater stingrays (Chondrichthyes: Potamotrygonidae) at Marajó Island, mouth of the Amazon River

Abstract

Experimental fisheries were carried out at Marajo Island in regions with different environmental characteristics and using various fishing gears. A total of 344 specimens belonging to five described species (Plesiotrygon iwamae, Paratrygon aiereba, Potamotrygon motoro, Potamotrygon orbignyi and Potamotrygon scobina) and to two undescribed species were captured. The specific abundance and biomass were related with the environmental characteristics of the sampling points. Number of specimens captured, catch per unit effort (CPUE) and total weight values indicated that Potamotrygon motoro is the predominant species in this region, especially in the center of the island. Larger specimens of Potamotrygon motoro were registered in Arari Lake, while smaller ones were present on the island's bordering areas. As other elasmobranchs, it is suggested that potamotrygonids present habitat occupation and use preferences related to environmental conditions.