Gray circles indicate turtle positions, and black circles indicate departures. © 2021 World Wildlife Fund. They then maintain an offshore heading until they reach the open sea. Worldwide, hundreds of thousands of sea turtles a year are accidentally caught in shrimp trawl nets, on longline hooks and in fishing gillnets. 2004). 2002). As many leatherbacks utilize high-latitude foraging areas in the summer and fall before migrating south thousands of kilometers (Ferraroli et al. The Leatherback Turtle (Dermochelys coriacea) is the only existing species of the family Dermochelyidae.They are the largest of living sea turtles, growing up to 2 metres and weighing as much as 900 kg. Pacific leatherbacks migrate from nesting beaches in the Coral Triangle all the way to the California coast to feed on the abundant jellyfish every summer and fall. Their breeding grounds are in the tropics*, but they migrate long distances to reach their feeding grounds, which are usually in colder waters. Female leatherbacks nest an average of 5 to 7 times within a nesting season, with an observed maximum of 11 nests. Supplementary material can be found at http://www.beheco.oxfordjournals.org/. 2006). Washington, DC 20037. This longitude lies between Georges Bank and Cape Breton Island (Figure 1) and may indicate that these 2 areas provide foraging opportunities later into the season than nearby longitudes. Here we used Cox's model to analyze time-dependent latitude, latitude2, longitude, longitude2, day length, depth, SST, 1-week lagged average SST, chlorophyll-a concentration, 1-week lagged average chlorophyll, and monthly NAO index along with the static variables of tagging location, sex, carapace length, maturity (≥140 cm standard curved carapace length), and 2-way interactions between these variables in relation to the probability of a turtle leaving for the south. Leatherbacks follow their jellyfish prey throughout the day, resulting in turtles "preferring" deeper water in the daytime, and shallower water at night (when the jellyfish rise up the water column). Inset dotted gray lines follows the 200-m depth contour. 2004; Hays et al. The 95% CIs are in days. Their biggest threats are the result of human activity. From left to right: A female leatherback turtle leaves a beach in French Guiana after nesting; About 60 days later, hatchlings come out of the nest and head to the sea; Adult leatherback caught in a net. Inset shows locations discussed in the paper. Departure rate was not significantly affected by 1-week lagged average chlorophyll concentration in the central latitudes (39.1°N–45.0°N) of the study area. All rights reserved. Ever the food-motivated individuals, some turtles head to cooler waters instead of warmer ones. For each 1° increase in latitude at the mean chlorophyll concentration of 0.72 mg/m3, the departure rate increased by a factor of 3.24 (95% CI: 1.87–5.61). Predicted proportion of leatherbacks that have initiated their southward migration at mean latitude, longitude, and 1-week lagged average temperature and chlorophyll for the study. Georges Bank is one of the most productive shelf ecosystems in the world (Backus and Bourne 1987). We found that leatherbacks are more likely to depart from warmer and, in the northern range of this study, more chlorophyll-rich waters. 2006), we have little understanding of what variables influence the transition between these 2 states. Egg collection on many turtle nesting beaches is a very serious threat, especially in Southeast Asia where a culture of legal egg collection leads to the removal of tens of thousands of eggs. These findings corroborate identification of physiological and behavioral adaptations to cold-water foraging in this species (Frair et al. This meant walking a 4-kilometer stretch of natal beach every night between 8 p.m. and 8 a.m. looking for turtles. We thank B. Fricker, H. Fricker, J. Fricker, K. Martin, and B. Mitchell for their instrumental contributions to all aspects of fieldwork. 1250 24th Street, N.W. Waters off the northeast tip of Cape Breton are a primary field site for our research on leatherbacks, and we directly observe many turtles foraging there. 2004; James, Ottensmeyer, and Myers 2005; Eckert et al. The NAO also appears to affect the migratory schedule of many birds (Forchhammer et al. Leatherbacks undertake the longest migrations between breeding and feeding areas of any sea turtle, averaging 3,700 miles each way. So why might leatherbacks in the north migrate so much earlier? The last dates of foraging were consistent with migration dates estimated from speed and diving behavior (James, Ottensmeyer, et al. These satellite tags do not harm the turtles in any way and are designed to eventually fall off. Chlorophyll and SST were set at mean values (17.7 °C and 0.72 mg/m3). Points indicate turtle departures, and dashed lines show the 95% confidence limits. 2006), to breeding and foraging areas in tropical and subtropical waters (James, Ottensmeyer, and Myers 2005; Eckert et al. 2001; Norris et al. What do sea turtles eat? 2004; James, Ottensmeyer, and Myers 2005). Despite decades of research, many questions remain about Atlantic leatherback migration patterns, distribution, habitat use, foraging ecology, physiology, population structure, and health. This practice has contributed to the local extinction of leatherbacks in Malaysia. Each 1 °C increase in 1-week lagged temperature increased the departure rate by 48.7% (95% CI: 0.71–120%). Although their distribution is wide, numbers of leatherback turtles have seriously declined during the last century as a result of intense egg collection and fisheries bycatch. 2006; Jonsen et al. 2007). From 2004 to 2017, only 55 leatherbacks a year came to forage. Reconstructed movements of 16 Argos-tracked leatherback turtles during their migration in the Atlantic Ocean from 2005 to 2008. Make a symbolic turtle adoption to help save some of the world's most endangered animals from extinction and support WWF's conservation efforts. Although their distribution is wide, numbers of leatherback turtles have seriously declined during the last century as a result of intense egg collection and fisheries bycatch. Adult leatherback sea turtles grow up to 2.4 meters (8 feet) long and can weigh 0.91 metric tons (1 ton). Department of Biological Sciences, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia, Canada B3H 4J1. River herring (Alosa pseudoharengus, Alosa aestivalis) are also more likely to begin downstream migration when prey abundance is low (Yako et al. The paper was about leatherback turtles migrating from their summer feeding grounds near Nova Scotia to head down to wintering and nesting areas in the south. First a little background. As fishing activity expands, this threat is more of a problem. SST appears to influence the distribution (Davenport 1997), nesting date (Weishampel et al. Higher temperature and, in the northern range of the study, higher chlorophyll concentration increased departure rates, perhaps due to the acceleration of the life cycle of the leatherback's gelatinous prey and/or increased feeding efficiency in these areas. Cues for the onset of migration have been studied extensively in birds (e.g., Both et al. Join us to make change. For example, temperature has a significant effect on the arrival date of some migrating birds (Sparks and Braslavská 2001; Hüppop O and Hüppop K 2003; Gunnarsson et al. Because the state-space estimates do not correspond directly to the time that the tag recorded SST, the median SST for observations within the 6-h period was used. Leatherbacks migrate the farthest of all sea turtles, and dive the deepest. WWF aims to reduce turtle bycatch by working with fisheries to switch to more turtle-friendly fishing hooks ("circle" hooks) and advocates for the use of devices that exclude turtles from nets. Each year adult leatherbacks migrate from their northern foraging grounds, including critical habitat off eastern Canada (James, Sherrill-Mix, et al. Migrated nearly 13,000 miles from Indonesia to the local extinction of leatherbacks Malaysia., as leatherbacks can maintain body temperature well above ambient ( Frair et al: one migrated nearly 13,000 from... 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