Movements and diving behaviour of leatherbacks incidentally captured by Uruguayan commercial and artisanal fisheries in the South-western Atlantic Ocean

MILAGROS LÓPEZ-MENDILAHARSU ; PROSDOCIMI LAURA,; ANDRÉS DOMINGO; PHILIP MILLER

Baja California

Congreso; XXVIII Simposio Internacional de Especialistas en Tortugas Marinas; 2008

Leatherback turtles (Dermochelys coriacea) are the most widely distributed of reptiles occurring throughout tropical and temperate oceans of the world, but the incidental killing of leatherbacks by fisheries has been implicated in the dramatic decline of major leatherback populations around the world. It is known that this highly migratory species can perform transatlantic migrations from tropical nesting beaches to temperate foraging areas, where they remain for prolonged periods. Incidental capture numbers of leatherbacks in the SW Atlantic (off the coast of Brazil, Uruguay and Argentina) are alarming as documented in several studies in the region (Domingo et al. 2006). However, information on how leatherbacks utilize oceanic and coastal areas along the SW Atlantic Ocean is still scarce. To the date, information on the distribution and movements of leatherbacks in the region was restricted primarily to fishery bycatch data, flipper tag recoveries, strandings and anecdotal observations; but the recent use of satellite transmitters has provided new insights about the movements and behaviour of this species at sea. Here we present the movements and diving behaviour of four leatherbacks (two females, one male and one subadult) fitted with satellite transmitters in 2005 and 2006. One deployed in an individual after being incidentally captured by a coastal gillnet in the Rio de la Plata estuary, and the other three deployed by scientific onboard observers (PNOFA-DINARA, Uruguay) on leatherbacks incidentally captured during pelagic longline fishing operations in the SW Atlantic. Turtles displayed different diving patterns (spatial and temporal variations) influenced by oceanographic features of the utilized regions. High-use areas of leatherback turtles delineated by using fixed Kernel Home Range analyses will be presented for the first time for the SW Atlantic. This study is part of a Trans-Atlantic Leatherback Conservation Initiative (TALCIN), to increase the knowledge of movements of leatherbacks in the Atlantic basin in order to contribute towards the identification of hot-spots of interaction between leatherbacks and fisheries.