Hábito alimentar do amuré (gobioides broussonnetii) na Baía de Marajó, foz amazônica e considerações sobre a sua captura por pescadores locais

Abstract

Amurés are medium-sized fishes of the family Gobiidae, belonging to the genus Gobioides, of whose 8 species only G. broussonnetii and G. grahamae occur in Marajó Bay, at the Amazon mouth. Our study is mainly focused on G. broussonnetii, collected in large numbers in the surroundings of the municipality of Vigia, Pará state. This species is characterized by a very elongated body, a reduced eye, and a single, continuous dorsal fin. It lives in low salinity waters, in estuaries and mangroves, in direct contact with the substrate, in which it commonly buries itself. Fishermen from the Guajará-Mirim River use their own method to capture it in medium-depth waters. They delimit an area of approximately 10m2 at a distance of 6m from the river bank, measured at low tide. They then bury a bamboo pole, approximately 4 meters long, in a portion of the area, and at a depth of 2.5 meters, tie a 2-meter long tarrafa with a 10-mm diameter mesh, with weights around it, and keep it open. They then make several dives of 40 seconds at a time and step around the net to unhook the buried fish. This is done over the entire 10 m2 area, catching an average of 7 dozen amurés in a period of one and a half hours. The species is not used as human food, but as bait for other cutthroat fish, and there are fishermen who depend on income from this live bait catch. In our study of the feeding habit of the common walleye, we found that the stomach contents of the specimens examined consisted of 95% algae of the class Cyanophycea and 5% spicules of porifera. The cyanophycean genera found included, in descending order of occurrence, Actinocyclus, Coscinodiscus, Polynuxeis, and Triceratium. We found that the amurés, although exhibiting characteristics typical of a predator (conical teeth, short and thick gill tracks), exhibit a diet consisting mainly of phytoplankton.