Using maternal DNA to evaluate egg translocation success of the loggerhead sea turtle (Caretta caretta) at Chincoteague National Wildlife Refuge
The federally threatened Caretta caretta nests on Assateague Island, Virginia. From 1969 to 1979, eggs from nests laid on Cape Romain NWR, SC were translocated to Chincoteague NWR. The main goal was to extend the U.S. Atlantic loggerhead breeding range to protected beaches physically and ecologically similar. Females that were part of the transplant project may now be returning to their hatch and release sites. Our current management aims to protect current nesting sea turtles. We are participating with the University of Southern Georgia on a genetics study to gather more information on nesting females. With this said, are we seeing the effects of the management effort from the 70’s now?, what is the hatching success of nests? and, is the current management aiding the hatch success of nests?. The areas of study were Chincoteague NWR, NASA Wallops Island- Virginia and Assateague Island National Park, Maryland. We collected an egg (24 hours of deposition) and GPS points from each nest found to compare location and nesting frequency of the individuals. Maternal nuclear microsatellite DNA was isolated from the eggshells of loggerheads. Genotypes derived from these eggshells allow an individual assignment of nests and demographic parameter estimates for loggerhead nesting populations.
Staff recorded 16 crawls from 1970 – 1999 on CNWR and Wallops NASA; 6 false crawls and 10 nests. From 2005 to2009, there was an increase in loggerhead crawls and nests in Assateague Island, approximately 30 years after the trasnslocation. There has not been active nesting at CNWR since 2013. However, there has been a consistent nester in Wallops NASA, with 6 nests between 2010 and 2012. According to our data, this turtle has laid around 543 eggs which only 226 of them hatched (41% of the clutch). Another individual (CC003355) nested 3 times at CNWR during 2011; unfortunately all of them were lost due to hurricane Irene. No nests or hatchlings have been knowingly lost to human causes. Because sea turtle nests are such a rare occurrence, predators are probably not keyed into and actively looking for sea turtle nests. No nest has been reported as predated. Management activities have kept mortality below so far. However, if turtle nesting increases on the Refuge there may be more overlap between human disturbance factors and turtle nesting. The program has been successful as far as nesting attempt frequency although nesting success has not been statistically significant.