Important juvenile developmental areas at the Bijagós Archipelago, Guinea-Bissau
In March and October of 2018 the IBAP and a team of researchers from the University of Exeter, the MARE - ISPA, Instituto Universitário, the Faculty of Sciences of The University of Lisbon and the Faculty of Veterinary of the University of Lisbon, travelled to the remote islands of Unhocomo and Unhocomozinho to study the green turtle juvenile aggregations.
Our work at Unhocomo and Unhocomozinho Islands
During the two field campaigns at we captured 23 juvenile green turtles, which were foraging in shallow coastal waters. To capture the turtles we enclosed areas of intertidal rocks or mangrove using an entanglement net of 800 m length, with the help of a small canoe. The net was, on average, submerged 1h at each place. During this period we monitored the enclosed area and when a turtle was spotted it was lead towards the net, captured by hand and brought on-board our research vessel.
All turtles were found to be in good health conditions, although four had small external tumours of fibropapillomatosis (FP) – a benign neoplastic disease of marine turtles. We collected epidermal biopsy samples from all turtles for genetic analysis. We also collected samples of nesting females from the major rookery of Poilão Island, so we can compare their ‘genetic signal’ with that of the juveniles, to find out if the younger animals were born at Poilão. We will also compare the ‘genetic signal’ of these turtles with a database existent for the Atlantic, to explore the possibility of more distant origins for the juvenile green turtles foraging in the coastal waters of Unhocomo and Unhocomozinho Islands.
For a robust genetic analysis we will need more samples from juvenile green turtles foraging at the Bijagós, so we will continue our in-water monitoring of these aggregations and will continue to sample. And in addition to the genetic studies we have a PhD student researching the diet of the juveniles and prey availability at their foraging grounds. We also have a veterinary master student analysing FP tumour samples, so hopefully we will soon learn more about the prevalence and virulence within this aggregations.
We are very excited to have identified these key developmental grounds for green turtles, and we will be exploring further sites in the Bijagós, hoping to find more juvenile aggregations. Additionally we have established collaborations with the local communities to support marine turtle conservation at Unhocomo and Unhocomozinho Islands, and will work together in the monitoring of the juvenile green turtles.