Interações entre orcas Orcinus orca (Linnaeus, 1758) e falsas orcas Pseudorca crassidens (Owen, 1846) com a pesca de espinhel pelágico monofilamento no Atlântico Oeste Tropical

Abstract

Since 50`s, industrial fisheries have been damaged by cetaceans in all oceans, with different intensity levels. According to specialists, this behavior is named depredation, which occurs when the animals eat the fishes caught by a fishing gear. Killer whale has been cited as an animal that shows this kind of behavior often, otherwise other species as a false killer whale or sperm whale have been recorded doing fishing gear interactions. After the creation of the On Board Observers Program (PROBORDO) it was possible to cover all tuna fleet working in northeast of Brazil, based on Natal-RN, Cabedelo-PB and Recife-PE ports. The covering was made by board observers that get important information to the fisheries dynamic knowledge made by pelagic long line. Interactions between false killer whales and killer whales are cited as an important scientific subject, in relation to these fisheries type, that the present study pretends to show up. Factors like interactions type, groups’ size, qualitative and quantitative descriptions of depredated fishes and spatial location of the interactions were analyzed. The false killer whale showed greater occurrence on the study area than other species, generally within groups of few individuals, however, there were situations that the group was composed by hundreds of individuals. This species showed food preference about the target species of this fisheries kind, in other words, tuna and swordfishes instead of others catched, but in case of low productivity, they feed with squid used as a bait on the hooks. Killer whales were observed in the Tropical Western Atlantic, interacting with the fisheries. Also, there were accidental catches of the cited cetaceans by the fishing gear, what can bring serious damage to the individuals caughted.