Comparison of local knowledge about the bottlenose dolphin (Tursiops truncatus Montagu, 1821) in the Southwest Atlantic Ocean: New research needed to develop conservation management strategies

• Artisanal fishermen identify the bottlenose dolphin along of coast of southwest Atlantic Ocean.
• Positive interactions involves aid of bottlenose dolphin during fishing activities.
• In perception of fishermen the negative interactions are caused by bottlenose dolphin and can impair fishing.
• The local knowledge about bottlenose dolphin is different between the communities of Brazil and Uruguay.
• In Uruguay, the fishing area and the area of bottlenose dolphin occurrence do not overlap, in Brazil this overlap occurs.

The aim of this study was to compare the local knowledge of artisanal fishermen about interactions between the bottlenose dolphin (Tursiops truncatus) and fisheries in Brazil and Uruguay. Between 2008 and 2011, we performed 88 interviews in Brazil (N = 66) and Uruguay (N = 22). Fuzzy logic was used to identify fishermen who could recognize the bottlenose dolphin. Seventy-nine fishermen (89.8%) identified the bottlenose dolphin, with 40 (50.6%) describing positive interactions, and 21 (34.4%) reporting negative interactions. In Brazil, the local ecological knowledge about the bottlenose dolphin was considered partial but more elaborate, as such knowledge was still incipient in Uruguay. Decreasing the impact of artisanal fishing on coastal populations of bottlenose dolphins in the southwest Atlantic Ocean (SAO) will require the regular monitoring of their areas of use and the locations where gillnets are arranged; consideration the size of the dolphins' populations and the fishing effort in each region; and the participation of social actors through educational activities, particularly in Brazilian areas, and the participation of social actors through educational activities (particularly in Brazilian areas, where the fishermen evinced feelings of competition in relation to the bottlenose dolphin) and improvements in the living and income conditions of these communities. From these results we propose measures for reducing anthropic impacts on bottlenose dolphin populations, including monitoring areas of use and the locations of fishing along the SAO as well as integrated management between social actors – government – research institutes for decisions about fishery management.