The largest of the sea turtles, the leatherbacks, have remained somewhat of a mystery, despite being in existence for more than 65 million years. Studies that have been done on leatherback sea turtles in the past have only scratched the surface. A recent study shows data collected about the migratory animals from satellite and GPS tracking devices. The results of their study helps conversationalists to better understand their migration and diving habits.
The study, published in PLOS ONE on March 19, details what scientists learned by using satellite and GPS devises to track nine adults and 11 smaller leatherbacks from the Northeast U.S. to the Northwest Atlantic between 2007 and 2010. They were tagged and released from a vessel in Cape Cod, MA.
Kara Dodge and Molly Lutcavage used telemetry to track the leatherback sea turtles to better understand their seasonal habits, as well as their diving activities. Because they branched out in this study to cover more than the migrating habits of female sea turtles and their nesting habits, unlike many of the previous studies on leatherbacks, they were able to garner different results.
This study was the first of its kind in that it also looked at the habit of young leatherback sea turtles, as well as adult males. They kept track of the animals and their exact locations using GPS-linked and conventional Wildlife Computers, Inc ARGOS satellite time depth recorders (STDRs.) The average time for tracking the leatherbacks was 184 days.
The researchers noted their affinity to the Northeast U.S. shelf in the warmer months when they were able to prey on jellyfish. The seasons affected their habitats and migration patterns. The turtles dispersed into the Northwest Atlantic during the fall and winter months. The adults traveled farther north, while the smaller leatherbacks did not have the same incentive, as far as breeding and nesting needs.
As far as migrating, they traveled quickly through the Subtropic Atlantic from October to February and remained in the Tropical Atlantic once they reached it. This is generally where they bred and foraged until spring, when they usually traveled back to their habitat near the U.S.
They also studied the leatherback sea turtle’s diving patterns. They found that the turtles were fairly consistent with 90 percent of the dives occurring in shallow depths (less than 75 meters.) Furthermore, 90 percent of the dives lasted less than 32 minutes. The farther south they traveled, the deeper their dives were, however.
Leatherback sea turtles are on the red list of endangered species. Conservation efforts are focused on reducing the number of by-catches and interference with their nesting. The authors of this study hope to help conservationist better understand the migration patterns and behaviors of the endangered turtles in order to preserve the population. The study is expect to help NOAA, the U.S. Fish and Wildlife Service and the Massachusetts Division of Marine Fisheries in their conservation efforts.
The GPS tracking study that followed the seasonal migration of the leatherback sea turtles provides a better understanding as to where they are at certain times of the year and how they can be better protected.
By Tracy Rose