The following abstract has been recently presented at the last 31st Annual Symposium on Sea Turtle Biology and Conservation organized in the beautiful San Diego, California, 12-15 April, during the Population Assessment session.
ABUNDANCE ESTIMATES OF THE LOGGERHEAD SEA TURTLE (CARETTA CARETTA) IN THE PELAGOS SANCTUARY, NORTHWESTERN MEDITERRANEAN SEA
Giancarlo Lauriano1, Simone Panigada1,2, Paolo Casale3, Nino Pierantonio1,2 and Greg P. Donovan4
1 Institute for Environmental Protection and Research (ISPRA), Roma, Italy
2 Tethys Research Institute, Milano, Italy
3 Department of Biology and Biotechnologies “Charles Darwin”, University of Rome ‘La Sapienza’, Roma, Italy
4 The International Whaling Commission, Impington, Cambridge, UK
Systematic monitoring of density and abundance of large vertebrates is among the priority actions listed in the Pelagos Sanctuary Management Plan, ACCOBAMS and by the Specially Protected Areas and Biodiversity Protocol under the Barcelona Convention. Aerial line transect surveys were performed in winter and summer 2009 in the Pelagos Sanctuary (88,267 km2), NW Mediterranean Sea. Survey effort consisted of 82 parallel transects 10km apart. A total of 207 loggerhead sea turtles were sighted in 16,590 km surveyed (8,144 in winter and 8,446 in summer). Noticeable differences in turtles presence occurred between winter (9 sightings reported) and summer (198). The average summer ‘surface’ density was calculated by Multi Covariate Distance Sampling methods (MCDS) run by the program Distance. Density was 0.0453 turtles km-2, with a total ‘surface’ estimate of 4,001 animals (95% CV=15.17; 95% CI: 2956- 5413). The Pelagos Sanctuary, established primarily for the protection of marine mammals, appears to be also an important area for Mediterranean loggerhead sea turtles. Nevertheless, the area in summer face high human disturbances and the potential for human induced mortalities of turtles summering in the Pelagos Sanctuary is high. This paper shows that aerials survey which have been usually aimed to apex predators such as cetaceans, can be an useful and accurate tools to provide reliable and accurate data, for loggerhead sea turtle, too.