First satellite tracks of neonate sea turtles redefine the ‘lost years’ oceanic niche

Abstract

Few at-sea behavioural data exist for oceanic-stage neonate sea turtles, a life-stage commonly referred to as the sea turtle ‘lost years’. Historically, the long-term tracking of small, fast-growing organisms in the open ocean was logistically or technologically impossible. Here, we provide the first long-term satellite tracks of neonate sea turtles. Loggerheads (Caretta caretta) were remotely tracked in the Atlantic Ocean using small solar-powered satellite transmitters. We show that oceanic-stage turtles (i) rarely travel in Continental Shelf waters, (ii) frequently depart the currents associated with the North Atlantic Subtropical Gyre, (iii) travel quickly when in Gyre currents, and (iv) select sea surface habitats that are likely to provide a thermal benefit or refuge to young sea turtles, supporting growth, foraging and survival. Our satellite tracks help define Atlantic loggerhead nursery grounds and early loggerhead habitat use, allowing us to re-examine sea turtle ‘lost years’ paradigms.

Movement patterns of marine turtles in the Mediterranean Sea: a review

“…The only method available to investigate their movement patterns is through simulations of particle dispersals in large-scale oceanographic models (e.g. Hays et al 2010a), although promising new tracking techniques for small turtles are being developed (Mansfield et al 2014).…”

“…Tracking experiments on juveniles are fewer than those on adults, and are mostly limited to larger turtles foraging in neritic areas, where they usually settle after spending the first few years of their life in oceanic areas (Bolten 2003). Very little information is available on the movements of younger turtles during their pelagic developmental phase (but see Kobayashi et al 2008;Howell et al 2010;Mansfield et al 2014), when in fact it is believed that they move over large oceanic areas (Bolten 2003).…”

Active dispersal in loggerhead sea turtles ( Caretta caretta ) during the ‘lost years’

“…However, developments in electronic tracking and biologging capabilities, coupled with laboratory experiments, have begun to shed light on the predominant hypotheses of entirely passive at-sea behaviour and distribution [3][4][5][6]. It is now known that oceanic dispersal is a product of passive and active movements [7][8][9][10].…”

“…Extended time in the pelagic environment can make understanding their navigational behaviour and habitat selection along migratory routes difficult. This is especially true for sea turtles, which disperse into the ocean upon hatching and remain relatively undetectable for several years [2,3]. During this time, the gaps in knowledge of where they disperse, what habitats they use and the length of time they exploit these habitats, are characterized as the 'lost years' [2].…”

“…Emerging studies have begun to recognize that even early-stage turtles rely on some level of active swimming to achieve success with long-distance ocean transport [3,5]. In combination with well-known geomagnetic navigational cues [4], small amounts of directional swimming can exert a strong effect on migratory routes and endpoints within ocean circulation [3,10,11].…”