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.

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It has been proposed that because marine turtles have environmentally determined sex by incubation temperature, elevated temperatures might skew sex ratios to unsustainable levels, leading to extinction. Elevated temperatures may also reduce availability of suitable nesting sites via sea level rise. Increased tropical storm activity can directly affect nest site moisture, embryonic development, and the probability that nests will survive. Here, we question some of these assumptions and review the limits of sex ratio estimates. Sea turtles may be more resilient to climate change than previously thought, in part because of hitherto unappreciated mechanisms for coping with variable incubation conditions.

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Significant gaps exist in our understanding of early sea turtle life stages. Dispersal and habitat use of young oceanic sea turtles are largely inferred. Historically, available tracking technology and tag attachment methods were limited by small body sizes and rapid growth of neonate sea turtles. We tested methods in the laboratory for attaching small solar-powered satellite tags to neonate loggerhead sea turtles Caretta caretta, including harnesses, hard epoxy and neoprene-silicone mounts. Non-harness attachments were tested on turtles with clean carapaces and carapaces treated with an acrylic base-coat. Turtle growth and condition were measured among treatment and control groups. We tested surrogate solar cells, coated with clear silicone antifoulant for biofouling and performance, and field tested the performance of 7 solar-powered satellite tags on neonate loggerheads released off southeastern Florida (USA). Attachments with acrylic base-coats remained affixed 4-to 8-fold longer than on untreated carapaces. Harness attachments resulted in long-term tag retention (> 60 d). However, harness and hard epoxy attachments did not adjust for turtle growth; we do not recommend these methods for rapidly growing neonate turtles. The method with longest retention was a neoprene-silicone attachment on an acrylic base-coat. Growth and condition were comparable among treated and control turtles using this flexible neoprene-silicone-acrylic attachment. Field-tested tags transmitted for 38 to 172 d. There were significant differences in charge rates of tags treated with an antifoulant and untreated tags; however, all tags charged optimally and transmitted high-quality locations. Our data suggest that small solar-powered tags are viable tools for monitoring the in-water behavior of oceanic sea turtles.

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Persistent organic pollutants (POPs) are recognized manmade threats to sea turtle populations, but substantial uncertainty exists surrounding their exposure to contaminants and their sensitivity to toxic effects. This uncertainty creates difficulty for conservation managers to make informed decisions for the recovery of these threatened species. To provide baseline concentrations and spatial comparisons, we measured a large suite of POPs in loggerhead sea turtle (Caretta caretta) egg yolk samples collected from 44 nests in three distinct U.S. locations: North Carolina (NC), eastern Florida (E FL), and western Florida (W FL). The POPs included polychlorinated biphenyls (PCBs), organochlorine pesticides such as dichlorodiphenyltrichloroethanes (DDTs), chlordanes, mirex, dieldin, hexachlorocyclohexanes (HCHs), hexachlorobenzene, and toxaphene congeners, as well as polybrominated diphenyl ether congeners (PBDEs). Persistent organic pollutant concentrations were lowest in W FL, intermediate in E FL, and highest in NC egg samples, with several statistically significant spatial differences. This increasing gradient along the southeast coast around the Florida peninsula to North Carolina was explained partly by the foraging site selection of the nesting females. Data from previous tracking studies show that NC nesting females feed primarily along the U.S. eastern coast, whereas W FL nesting females forage in the Gulf of Mexico and Caribbean Sea. The E FL nesting females forage in areas that overlap these two. The foraging site selection also results in exposure to different patterns of POPs. An unusual PBDE pattern was seen in the NC samples, with nearly equal contributions of PBDE congeners 47, 100, and 154. These findings are important to managers assessing threats among different stocks or subpopulations of this threatened species.