Loggerhead turtles also live in the open sea
In the Atlantic, too, the majority of adult loggerhead turtles (Caretta caretta) possibly live in the open sea and not, as previously assumed, mainly off the coast. This is the conclusion reached by scientists from the University of Exeter after several months of tracking the migration routes of the large marine reptiles between the Cape Verde Islands and the west coast of Africa.
Brendan Godley's team strapped a tracking device to the back shell of ten females on the Cape Verde Islands while they were laying their eggs. After the animals buried their eggs, scientists used satellite telemetry to track them. Only three of the women, who weighed up to 150 kilograms, set course for the coasts of Sierra Leone and Guinea, about 1250 kilometers further east, and looked for a hunting ground in shallow water. The other seven turtles roamed the open sea with no specific destination, tracking their prey near the surface.
Obviously, the body size of the animals also depends on their habitat: the coast turtles were significantly larger and could dive longer and deeper than their conspecifics on the open sea. However, Hawks and her team do not yet know whether the open-water inhabitants are smaller because their hunting ground is not as rich as on the coast, or whether the turtles first have to grow to a certain size and then to a depth of 60 meters near the coast to be able to dive down to the food-rich seabed.
With their study, the scientists confirm similar research results from Japan and point out that it is not enough to just protect habitats near the coast. The large marine reptiles are mainly threatened by deep-sea fishing. Every year, thousands of them get caught in nets or injure themselves on hooks designed to catch fish. According to the scientists, both the West African states and the South American countries that fish in international waters should therefore be included in protection programs for the highly endangered sea turtles.
