Habitat use, site fidelity and conservation opportunities for juvenile loggerhead sea turtles in the Río de la Plata, Argentina

MAXWELL S; ACHA EM; BRUNO I; ÁLVAREZ K; GONZÁLEZ CARMAN V; ALBAREDA D

Lima

Simposio; 36th Annual Symposium on Sea Turtle Biology and Conservation; 2016

The loggerhead turtle (Caretta caretta) is listed as Vulnerable on the IUCN Red List due to threats that spread across its geographic range. Among all the threats faced, the mortality of juveniles and adults due to bycatch in longline, trawling and gillnet fisheries deployed in foraging grounds seems to have the most detrimental effects on the populations because these stages offer the greatest potential for population recovery. Thus, knowledge of the behavior and spatial distribution of individuals in foraging grounds may help design more effective, local conservation strategies, such as bycatch reduction technologies or time-area closures. This study assesses the habitat use of juvenile loggerheads in the Río de la Plata estuarine area, at the boundary of their distribution in the temperate SW Atlantic. Data from the satellite tracking of 6 neritic juveniles are analyzed through switching state-space models and kernel density estimation to identify preferential putative foraging areas and routes. Results indicate that immature turtles exhibit a strong foraging site fidelity to the Río de la Plata; either by remaining in the same 8,000 km2-area during 60% of their foraging time (7-8 months) or by migrating back to the same foraging spot in successive years (inter-annual site fidelity). Some loggerheads overwinter in coastal, warmer waters off Brazil and Uruguay, and also in oceanic areas. The fidelity of juvenile loggerheads to the Río de la Plata encourages site-base conservation tools. Spatial planning may result in special management areas supported by current regional treaties.