Leatherback turtles go with the flow

Not much is known about the world's largest living turtle, the leatherback. So-called for its tough, oily skin and lack of a hard shell, the behavior and habitats of this critically endangered turtle have remained a mystery. In this week's PLoS Biology, marine biologist Barbara Block and colleagues give us the largest study to date on leatherback turtles, unveiling the turtles' behavior, in doing so, providing methods that could be used to protect them. The authors tagged the turtles at a major nesting ground at in Costa Rica, then tracked 46 female leatherbacks from 2004 to 2007, showing their habits and migration routes in the Eastern Pacific over the course of three years. Block et al. found that after nesting, the turtles headed south into the open ocean in search of food. After passing the warm waters of the equator, where the turtles responded to strong ocean currents with rapid, directed movements to maintain their southern route, they continued on to the low-energy and low-productivity region of the south waters. Here, the authors reveal that the turtles succumbed to the physical forces of the ocean, as their migration routes were influenced by the ocean's currents. From the study, the authors were able to identify to specific high-use areas that the turtles occupy.

The leatherback turtle population in the Eastern Pacific has declined by 90% in the past two decades. Leatherbacks begin life as eggs on the beach and are subject to predation the minute they hatch and attempt to crawl to the ocean. From birth through adolescence, they are vulnerable to birds and other sea creatures. By the time they are full-grown, however, leatherbacks don't face many threats from predators. Those that do make it to adulthood have one major concern: humans. The massive decrease in the leatherback population is due in large part to fisheries – turtles get caught as bycatch in long-line fishing nets meant for other sea creatures.

In organizing a multi-national study over several years is no easy feat, and in charting the patterns, behaviors and migration paths of leatherback turtles, Block et al. shed light on these mysterious sea creatures. This new information will help existing multinational conservation programs identify regions in the migration corridor that will benefit from immediate conservation action, including improved monitoring to help leatherbacks steer clear of them on their journeys and regulation of long-line fishing to prevent the leatherbacks from becoming even more endangered—and ultimately set them on the path to recovery.

Source: Public Library of Science