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Marine Ecology Progress Series

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MEPS 437:291-302 (2011)  -  DOI: https://doi.org/10.3354/meps09261

Aerial survey abundance estimates of the loggerhead sea turtle Caretta caretta in the Pelagos Sanctuary, northwestern Mediterranean Sea

Giancarlo Lauriano1,*, Simone Panigada2,1, Paolo Casale3, Nino Pierantonio1,2, Greg P. Donovan4

1Institute for Environmental Protection and Research (ISPRA), Via di Casalotti 300, 00166 Roma, Italy
2Tethys Research Institute, Viale G. B. Gadio 2, 20121 Milano, Italy
3Department of Biology and Biotechnologies ‘Charles Darwin’, University of Rome ‘La Sapienza’, 00185 Roma, Italy
4The International Whaling Commission, The Red House, 135 Station Road, Impington, Cambridge, CB24 9NP, UK

ABSTRACT: Aerial line transect surveys, totalling 16590 km, were performed in winter and summer 2009 in the Pelagos Sanctuary, NW Mediterranean. A total of 207 loggerhead sea turtles were sighted, with only 9 sightings during the winter. In this season average raw ‘surface’ density (i.e. animals at or near the surface) was 0.002 turtles km–2, and on the basis of line-transect analysis, we estimated 237 specimens (CV = 34.33%; 95% CI = 122–461). The summer estimate resulted in 4083 animals at surface (CV = 14.59%; 95% CI = 3061–5466) in the study area, with a density of 0.046 km–2. Results indicated strong seasonal differences and lower densities than those found in comparable surveys in Spanish Mediterranean waters. Nevertheless, the ecological and oceanographic features of the Pelagos Sanctuary, established primarily for the protection of marine mammals, render it an important area also for Mediterranean loggerhead sea turtles. The potential for human-induced mortalities of turtles summering in the Pelagos Sanctuary is high. In this context, it is vital to obtain reliable estimates of absolute and relative abundance over time, monitor the status of loggerhead sea turtles and inform the development of effective conservation actions. This study illustrates the ability of aerial surveys to provide such data in this area.


KEY WORDS: Loggerhead sea turtle · Caretta caretta · Pelagos Sanctuary · Aerial survey · Abundance · Seasonal distribution · Distance sampling


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Cite this article as: Lauriano G, Panigada S, Casale P, Pierantonio N, Donovan GP (2011) Aerial survey abundance estimates of the loggerhead sea turtle Caretta caretta in the Pelagos Sanctuary, northwestern Mediterranean Sea. Mar Ecol Prog Ser 437:291-302. https://doi.org/10.3354/meps09261

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