Virginia and Maryland Sea Turtle Research and Conservation Initiative
Mark Swingle – Virginia Aquarium & Marine Science Center, Virginia Beach, USA
This project of Virginia Aquarium was initiated in 2011 and involves a multi-faceted study to update the state of knowledge for sea turtles in Chesapeake Bay and ocean waters off Virginia, USA. The project includes: 1) collecting data from aerial surveys and satellite tags to estimate abundance; 2) using the results of satellite tagging and geospatial analysis to better understand habitat use; 3) studying stranded animals to identify the causes of mortalities; 4) investigating sea turtle diets to document their primary food resources and nutritional status; and 5) development of a sea turtle conservation plan for the Virginia and Maryland study area. The loggerhead sea turtle (Caretta caretta) is the primary focus and is the most abundant species in the study area. Other sea turtle species are also present, including Kemp's ridley (Lepidochelys kempii), green (Chelonia mydas), leatherback (Dermochelys coriacea) and the rarely seen hawksbill (Eretmochelys imbricata).
Sea turtle abundance and distribution is being studied utilising aerial line-transect surveys and satellite tagging. Sea turtles are acquired from the wild through direct capture methods or stranding and rehabilitation, and then released with satellite tags. Data from satellite tagging allows for determination of average time spent on the surface, an important component for estimating seasonal sea turtle abundance when paired with aerial survey data. The results of satellite tagging, including both location and dive data, can also be used through geospatial analysis to investigate habitat use in the study area. Stranded animals provide another valuable source for scientific study. Virginia averages more than 220 stranded sea turtles per year, representing one of the highest levels of mortality per kilometre of coastline for any state in the USA. During this project, stranded animals are thoroughly examined both externally and via necropsy to determine cause of death and to collect samples for the study of life history, diet and nutritional status.
Preliminary results for the study area suggest that each year there are tens of thousands of sea turtles in ocean waters up to 40 miles offshore of Virginia and thousands of sea turtles in Chesapeake Bay. Animals satellite tagged in Virginia inhabit Chesapeake Bay and mid-Atlantic ocean waters in summer and move south to North Carolina and as far as Florida in winter. Some turtles move to offshore ocean waters in winter and one animal was successfully tracked for more than 500 days. Sea turtle strandings in the study area remain high and more than 900 animals have been examined through the end of 2014. Necropsy examinations reveal that some of the leading causes of mortalities involve human interactions, such as fishing gear entanglements, boat strikes and marine debris ingestion. Sea turtle diets are being studied through detailed analysis of gut contents from stranded animals. Stable isotope analysis of various tissue samples is also being used to attempt to better understand both short- and long-term sea turtle prey selection and nutritional status.
This project will end in 2015 with completion of an updated sea turtle conservation plan for Virginia and Maryland. The project is funded through a NOAA Section 6 Species Recovery Grant awarded to the Commonwealth of Virginia's Department of Game and Inland Fisheries. The research is being conducted by Virginia Aquarium with assistance from Maryland's Department of Natural Resources and additional collaborators including: Dr. Kate Mansfield, University of Central Florida; Dr. Erin Seney; Dr. Craig Harms, North Carolina State University; Dr. Jason Schaffler, Old Dominion University; Riverhead Foundation for Marine Research and Preservation; Research Unit for Wildlife Population Assessment, University of St. Andrews.