Freshwater dolphin/fisheries interaction in the Central Amazon (Brazil)

Abstract

An analysis of the relative importance of different types of fishing gear on Amazon dolphin mortality based on samples of 33 Inia geoffrensis and 34 Sotalia fluviatilis revealed the lampara seine was most lethal (82.8 %) for Inia whereas drifting and fixed gill nets (38.3 % and 35.3 %, respectively) were most important in Sotalia mortality. These three types of gear accounted for a total of 92 % of all Inia captures and 88.2 % of Sotalia incidental captures. The use of nylon gill nets in fishery in the Amazon is widely spread throughout the whole region, and with increasing fisheries pressure the potential for dolphin/-fisheries interactions is much greater. Competition between man and dolphin for commercial fish is still minimal in the Central Amazon. Dietary analysis has shown that only 43 % of 53 identified prey species are of commercial value and that the dolphins generally prey on size-classes of fish below those of commercial interest. Interviews with fishermen in the boats, in the fishmarket and in the shops supposedly selling dolphin products were conducted in an attempt to quantify the overall incidental kill attributed to commercial fisheries operations. The results showed that in the Central Amazon dolphin catches are incidental and only a very small number of these carcasses are used for commercial purposes.