Sea turtles are animals with a complex life cycle as they exploit distinct feeding habitats throughout their lives. These species perform large-scale migrations between feeding areas and nesting beaches making use of their incredible orientation ability. After birth, the baby sea turtles enter the sea and start an oceanic phase where several studies have demonstrated that their movements are mainly linked to the oceanic currents.
Loggerhead sea turtle returning to the sea after having laid its eggs.
During this phase, the juvenile turtles with a pelagic feeding disperse from their region of origin and can perform transoceanic migrations. Upon reaching sexual maturity, the individuals return to their region of origin exhibiting a behaviour known as "natal homing" (Bowen et al. 2004).
During the mating period, males and females go to the nesting beaches where they were born presenting a behaviour known as phylopatry. This phylopatric behaviour results in genetical differences among the nesting populations, even though when mating with females of different populations, males may generate a gene flow (see Bowen and Karl 2007 for revision). Molecular studies have turned out to be a key tool when it comes to define the population structure and connectivity between the feeding and nesting areas, which are essential for the development of management and effective conservation plans (Bowen and Karl 2007; Lee 2008).
Of the seven species of sea turtles that exist today, six have been observed in Macaronesian waters: the loggerhead sea turtle (Caretta caretta), the green sea turtle (Chelonia mydas), the hawksbill sea turtle (Eretmochelys imbricata), the leatherback turtle (Dermochelys coriacea), the Atlantic ridley sea turtle (Lepidochelys kempii), and the olive ridley sea turtle (Lepidochelys olivacea).