Sea turtle conservation problems in Argentina: by-catch and marine debris ingestion

ALBAREDA DIEGO; LAURA PROSDOCIMI; KARINA ÁLVAREZ; JOSÉ LUIS DI PAOLA; VICTORIA MASSOLA; VICTORIA GONZÁLEZ CARMAN; RUBÉN DELLACASA; RAÚL GONZÁLEZ ; PABLO BORDINO ; MARCELA UHART

Baja California

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

seaturtle.org

The Regional Program for Sea Turtle Research and Conservation in Argentina (PRICTMA) was created in 2003. This regional program established a by-catch and stranding monitoring network along 3000 km of Argentinean coastline (Buenos Aires, Rio Negro and Chubut province), building on the expertise of local sea turtle work groups. Monitoring is conducted by means of beach surveys and a collaborative effort between researchers and fishermen. Data collected since 1997 shows that juvenile green turtles (Chelonia mydas) have been found stranded (total reported n=46, 32.6% of these from interviews) along the coast from Gualeguaychú (S33º 01'; O58º 31') to Puerto Pirámides (S42º 35'; O64º 17'). Incidental captures of C. mydas (total reported n=108, 18.8% of these by interviews) were concentrated in Buenos Aires province, from Quilmes (S34º 43'; O58º 15') to Ingeniero White (S38°47'; O62°16'). Although, some captures (n=3) have been recorded in San Antonio Oeste (S40º 45'; O64º 56'). Gillnets and shrimp nets were the most frequent fishing gear involved, although bottom trawl nets and pole and line were also a problem for this species. Subadult loggerhead turtles (Caretta caretta) have been found stranded (total reported n=48, 33.3% of these from interviews) from Buenos Aires city (S34º 38'; O58º 28') to San Antonio Oeste. Incidental captures of C. caretta (total n=38, 57.9% reported in interviews) were concentrated in Buenos Aires province, from Quilmes to Villa del Mar (S50º 18'; O72º 47'). Gillnets were the most frequent fishing gear involved in by-catch although bottom trawl nets were also seen to interact with this species. Subadult and adult leatherback turtles (Dermochelys coriacea) were found stranded (total n=42, 26.2% of these by interviews) from Quilmes to Monte Hermoso (S38º 59'; O61º 18'). Incidental captures of D. coriacea (total n=31, 48.4% reported in interviews) were concentrated in Buenos Aires province, from San Clemente del Tuyú (S36º 22'; O56º 44') to Monte Hermoso. Ingestion of marine debris has been documented for C. mydas from Buenos Aires city (S34º 38'; O58º 28') to Necochea (S38°32′; O58°45′). Pieces of plastic, plastic bags, polystyrene, fishing lines and cables have been found in turtle’s digestive tract. From December 2004 to April 2005, 37 C. mydas (mean = 38.31 cm, range = 33-56 cm LMC) recovered from gillnet by-catch in southern Samborombón Bay were necropsied. Ninety seven percent (n=31) of the digestive tracts analyzed had some kind of marine debris. Furthermore, 70% (n=7) of the turtles rehabilitated in rescue centers since 2000 have shed plastic debris while in captivity. To date, only one animal in rehabilitation has died due to intestinal obstruction by plastics pieces. This study presents a regional overview of the situation of sea turtles in Argentinean waters, and highlights incidental capture and marine debris ingestion as the most conspicuous conservation issues. Further exhaustive monitoring is needed to assess the mortality rate for these species due to by-catch in different types of fishing gear. Moreover, establishing the cause of death of stranded animals is pressing in order to evaluate the contribution of marine debris ingestion to sea turtle mortality.