Distribuição e abundância relativa de tubarões no litoral do estado de Pernambuco, Brasil

Abstract

The importance of sharks in northeatern Brazil has grown substantially in the last decade, not only because of their commercial value, but also due to a shark attack outbreak that took place off Recife, Pernambuco State. From December, 1994 to August, 1995, 10 research cruises were made on the continental shelf of Pernambuco State, using a bottom longline as fishing gear for sharks. A total of eight shark species and two ray species were caught, the first ones being much more abundant, accounting for a much higher proportion of the landed weight. The blacknose, sandbar and nurse sharks were the most abundant species. Specimens of tiger and bull sharks were also caught. Both of these species, known for their aggressive behavior, have been involved in the recent shark attack outbreak off Recife. Based on the pattern of distribution shown by the several species caught, it was possible to divide the continental shelf of Pernambuco in three different zones: (1) Inner Zone, from the beach up to 30 m depth; Close-to-Shore Area, with high abundance of blacknose shark, rays and catfish; (2) Middle Zone, between 30 and 50 m, an intermediary area between the shore and the continental slope, with low abundance and diversity of species; and (3) Outer Zone, from 50 m down to the continental slope; Close-to-Slope area, with high abundance of bony fishes, particularly Lutjanidae and Serranidae, and sandbar shark. Most of the sharks and rays caught, showed a great preference for moray bait, in spite of the low effort developed with it. Among the baits more commonly used, only the skipjack showed a higher catch of blacknose shark