Grantee Research Project Results
The Behavior and Conservation of Sea Turtles in Virginia, USAEPA Grant Number: U915977
Title: The Behavior and Conservation of Sea Turtles in Virginia, USA
Investigators: Mansfield, Katherine L.
Institution: College of William and Mary-VA
EPA Project Officer: Graham, Karen
Project Period: January 1, 2001 through January 1, 2004
Project Amount: $271,135
RFA: STAR Graduate Fellowships (2001)
Research Category: Fellowship - Zoology , Academic Fellowships , Biology/Life Sciences
The Chesapeake Bay and the coastal waters of Virginia serve as a principal developmental habitat for demersal juvenile loggerhead (Caretta caretta) and Kemp's ridley (Lepidochelys kempii) sea turtles. Green (Chelonia mydas) and leatherback (Dermochelys coriacea) sea turtles also are found within Virginia waters, although in fewer numbers. Sea turtles enter the Chesapeake Bay each spring/summer when the sea temperatures reach approximately 18°C. Aerial surveys and telemetry studies conducted in the 1980s suggest that between 5,000 and 10,000 juvenile loggerheads forage in the Chesapeake Bay each summer. Sea turtles that use the Chesapeake Bay as a summer foraging area emigrate with falling water temperatures in September and October and swim south along the coast of North Carolina where they pass Cape Hatteras in November and December. The objective of this research project is to investigate the behavior and conservation of sea turtles along the Virginia coastline.Approach:
The Virginia Institute of Marine Science (VIMS) has served at the National Marine Fisheries Service Sea Turtle Salvage and Stranding Network stranding center for Virginia since 1979. As such, the VIMS program has organized a statewide stranding network consisting of about 100 cooperating individuals and agencies. Dead stranded sea turtles are identified and measured. In addition, hundreds of sea turtles have been necropsied by VIMS scientists to determine the cause of death, sex, foraging habits, and to study age and growth.
Each year, between 200 and 300 sea turtle stranding deaths are recorded within Virginia's waters. The vast majority of these strandings are juvenile loggerhead and Kemp's ridley sea turtles. High turtle mortalities during the spring migration in late May and early June have been documented by VIMS for 21 years. These historical stranding data clearly show that more than one-half of the yearly turtle deaths occur in May and June when the turtles first enter the Bay. Kemp's ridleys also show an additional peak in strandings in the fall (October and November). When turtles first move into the Bay and when loggerhead and Kemp's ridley stranding mortalities are highest, mean water temperatures range between 18°C and 22°C within a highly stratified water column.
Some of the sea turtle mortalities may be attributed to entanglement in poundnet leaders. These are nets with large (16") mesh leaders set in the lower Chesapeake Bay where currents are strong and may entangle turtles when they first enter the Bay after the spring migration. When this occurs, many of these turtles are emaciated and weak. These mortalities drop off substantially by the end of June. At this time, turtles tracked using radio transmitters could forage around the nets with little threat.Supplemental Keywords:
fellowship, sea turtles, conservation, sea turtle conservation, Chesapeake Bay, Virginia, VA, loggerhead sea turtles, Caretta caretta, Kemp's ridley sea turtles, Lepidochelys kempii, green sea turtles, Chelonia mydas, leatherback sea turtles, Dermochelys coriacea, stranded sea turtles, turtle mortalities, spring migration, poundnet leaders.