Movement patterns of green turtles at a key foraging site: the Banc d’Arguin, Mauritania

Abstract

Interactions with fisheries is a major threat to sea turtles. However, space-use at foraging locations remains overlooked in many populations, preventing effective protection. We assess the space-use of 14 juvenile and 24 adult green turtles(Chelonia mydas) satellite-tracked in 2018–2022 within a foraging site of global importance for this species, the Banc d’Arguin in Mauritania, West Africa. Turtles exhibited a patchy distribution and used overlapping habitats irrespective of sexes and life stages. Mean individual home range was larger (151.5 ± 160.5 km²) than values reported in most green turtle populations. Individuals concentrated in two main areas used year-round. Inshore/offshore movements seem to occur within the central part of the Banc d’Arguin, with turtles moving to deeper areas during colder months. More than halfof the turtles performed within-season range shifts and switched between up to four distinct areas, with some individuals returning to previously visited sites. Turtles mostly exploited shallow areas (4.30 ± 3.42 m) and seemed to use disproportionally more of the areas inside the Parc National du Banc d’Arguin, than areas of similar bathymetry outside this marine protected area. This suggests that foraging green turtles have been benefiting from the management of the Park since it was established in 1976. However, turtles’ home range overlapped greatly with artisanal fisheries, which operate in the central shallow waters of the Park. The present study provides valuable ecological information that can be used to inform the planning of fisheries management zones, aiming to reduce the interactions between turtles and artisanal fisheries.

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ORCID for Julie Mestre: orcid.org/0000-0003-3020-8921

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