Feeding of Rhizoprionodon porosus (Elasmobranchii: Carcharhinidae), from Maranhão coast, Brazil

Abstract

The coast of Maranhão State has a big concentration of sharks, being the species Rhizoprionodon porosus Poey, 1961 the first in relative abundance. It is a small sized shark belonging to the family Carcharhinidae. The captures were conducted by artisan fishery using a fish net of stitch, between September/1997 and March/1999. An analysis of the stomach contents of 252 specimens of Rhizoprionodon porosus was conducted, aiming to determine the feeding habits of the species. The fresh specimens arrived at the fishing village of Raposa, and then were taken and processed in the Hidrobiology Laboratory of the Federal University of Maranhão. There they were measured and weighed, having the stomach removed and fixed in solution of formaldehyde at 10% for analysis. According to the Index of Relative Importance (I.R.I.), the shark Rhizoprionodon porosus feeds on Teleostei fish belonging to the families Stromateidae, Trichiuridae, Sciaenidae, Engraulidae, Tetraodontidae, Clupeidae and Batracoididae, snails of the genus Loligo, and crabs of the genera Callinectes and Penaeus. Rhizoprionodon porosus showed a piscivorous habit, and is considered an opportunistic predador.