Green turtle migration

Understanding the movements of #seaturtles helps us protecting them

Within the current project funded by the MAVA Foundation; ‘Consolidation of Sea Turtle Conservation in Guinea-Bissau’, the ISPA – Instituto Universitário, the University of Exeter, and the Faculty of Sciences of the University of Lisbon have partnered up with the IBAP to research the movements of green turtles within the breeding area, during their inter-nesting intervals (i.e. between clutches, as turtles nest three to six times each nesting season), and along their post-nesting migration, to understand their connectivity with distant foraging grounds.

During the nesting season of 2018 we have successfully deployed 20 satellite tracking devices on female green turtles found nesting at Poilão from August to November. Thanks to the satellite technology we are watching closely the daily movements of these green turtles and have already some very interesting findings.

“Some turtles travelled over 1000 km north to Mauritania, to forage in the waters of the Parc National du Banc d'Arguin

We have learned that some nesting females interchange between Poilão and the nearby islands of Meio and Cavalos, all within the João Vieira - Poilão Marine national Park, also supported by tag-returns from previous years. Others venture outside the limits of the marine protected area (MPA) in between clutches, which was unexpected, as marine turtles usually rest near the nesting beach while preparing for the next clutch. Lastly, once they laid all clutches for the season, the green turtles initiate their migration to distant feeding grounds and we were able to follow most of them on their route up north, to the coastal waters of the Parc National du Banc d'Arguin, Mauritania.

migratory routes of post-nesting green turtles

Next steps

The movements recorded during the inter-nesting intervals will be essential to renegotiate and re-design the limits of the MPA, while the knowledge on the post-nesting migratory routes and connectivity between breeding and foraging areas will be key to understand the threats to this population outside the MPA, to identify conflict areas with fisheries, and to establish collaborations with sea turtle conservation projects within the region. Along with other research being conducted, on the connectivity between nesting beaches and juvenile developmental areas, and on the factors that influence the reproductive success and its management (e.g. erosion, flooding, and predation), these findings will contribute to a better understanding of the conservation status and main threats of the green turtle in the Bijagós Archipelago, and we are looking forward for more results.

Author: Ana Rita Patrício