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Atlantic loggerhead sea turtle

The loggerhead sea turtle (Caretta caretta) inhabits open water, continental shelves, bays, estuaries and lagoons in temperate, subtropical and tropical waters [1]. Its West Atlantic range extends from Newfoundland to Argentina, with virtually all nesting occurring from North Carolina southward. Nesting between New Jersey and Virginia is very rare, but turtles regularly forage as far north as Nova Scotia.

The northwest Atlantic population accounts for 35-40% of the species' global nesting [1]. It is informally managed in five subpopulations: Northern (North Carolina to northeast Florida at about 29°), South Florida (from 29° on the Atlantic Coast to Sarasota on the Gulf Coast), Florida Panhandle (Eglin Air Force Base and beaches near Panama City), Dry Tortugas (seven islands west of Key West), and the Yucatan Peninsula (eastern Yucatan Peninsula, Mexico and Belize) [1, 4]. Nesting in Florida, which supports well over 95% of all U.S. nests and parts or all of four of the five subpopulations, increased substantially between the listing of the species in 1978 and 2005, though the trend can not be precisely described because survey efforts prior to 1989 were not systematic [2, 7].

South Florida Subpopulation (from 29° on the Atlantic Coast to Sarasota on the Gulf Coast)
South Florida contributed 89-92% of the U.S. nesting population between 1989 and 1998, and is the second largest population globally [1]. Its population trend dominates the entire U.S. trend. Annual nest counts indicate a substantial increase between the late 1970s and 2003, but the trend can not be precisely determined because of variable survey effort and methodology [2]. On Hutchinson Island, the only site with a consistent long-term survey, nest numbers grew by an average of 4% annually between 1981 and 1998, from 3,121 to 8,214 nests [1]. Systematic population-wide surveys began in 1989 [1]. They indicate a fluctuating but increasing trend between 1989 and 1998 [1]. The low point was 1989 (48,531), the high 1998 (83,442) nests. The species declined thereafter, establishing an overall stable trend between 1989 and 2002 [2]. The 2005 nesting season was better than 2004 [7], hopefully signaling an end to the 1998-2004 decline.

Northern Subpopulation (North Carolina to northeast Florida)
The Northern subpopulation is the second largest, contributing 6-11% of U.S. nests between 1989 and 1998 [1]. The population fluctuated considerably (low of 4,370 nests, high of 7,887) but without a discernable trend during this period. Long-term census data are not available for the subpopulation as a whole, but do exist for some regions within it. Cape Island, Cape Romain National Wildlife Refuge, South Carolina Cape supported approximately 15% of the nesting within the Northern subpopulation between 1989 and 1998 and its trend during that period correlated with the subpopulation as a whole [1], thus its long-term trend may index that of the subpopulation. Nesting declined between 1974 (2,800) and 1979 (1,090), but has remained stable since then, hovering around 1,000 nests. Its trend since the 1978 endangered species listing is stable. Nesting at Little Cumberland Island, Georgia fluctuated greatly, but without trend between 1964 and 1972, then declined drastically in 1973 and has remained at low numbers since [6]. Nesting at Bald Head, South Carolina remained stable between 1980 and 2004, but increased from 1980 to 1991 and declined from 1991 to 2002 [3]. Nesting in South Carolina as a whole, which supports over 50% of nesting in the subpopulation, declined by 60% between 1980 and 2002 [2]. The high point was about 6,600 nests in 1981; the low point was about 2,600 nests in 2002 [8].

Florida Panhandle Subpopulation (Eglin Air Force Base and beaches near Panama City)
The third largest subpopulation, the Florida Panhandle contributed 0.2% to 1.7% of U.S. nests between 1989 and 1998 [1]. Nest counts rose steadily during this period from 113 to 1,188 [1], and to 1,282 in 2002 [6], but the actual trend is unclear due to variable survey effort [2].

Yucatan Peninsula (eastern Yucatan Peninsula, Mexico and Belize)
The Yucatan Peninsula supported 1,051 nests in 1998, slightly less than the Florida Panhandle [2]. It appears to be stable or increasing, but long-term trend data does not exist [2].

Dry Tortugas (seven islands west of Key West)
The Dry Tortugas consists of seven islands 70 miles west of Key West [4]. It is the smallest subpopulation, averaging 213 nests between 1995 and 2001 (range: 184-270) [2]. The data are insufficient to determine a trend. Dry Tortugas National Park supports the largest nesting group within the subpopulation and within Monroe County, which includes all of the Florida Keys [4]. East Key and Loggerhead Key, two of the subpopulation's seven islands, support about 90% of the National Park's nests.

Other Areas
Small numbers of loggerhead turtles nest on the Gulf Coast outside the five identified subpopulations. About 100 turtles nested on the offshore islands of Louisiana, Mississippi and Alabama between 1960 and 1962, but declined by 1977 [1]. The Bon Secour National Wildlife Refuge in Alabama supported 21-31 nests between 1994 and 1998. The Gulf Islands National Seashore in Mississippi supported up to nine annual nests between 1990 and 1998. The Breton National Wildlife Refuge in Louisiana supported less than ten nests annually in 1989 and 1990. The Texas coast supported just 18 known nests between 1977 and 2000, eleven of them between 1966 and 1998. All but one were on the southern Texas coast. The Mexican states of Tamaulipas and Campeche supported small numbers in recent years, one to five in the former and about 50 in the latter.

The 1991 U.S. Fish and Wildlife Service Recovery Plan states that delisting can occur if over a period of 25 years (1) the adult female population in Florida is increasing, and nesting in Georgia, South Carolina and North Carolina returns to pre-listing levels (approx. 12,800 nests); (2) certain amounts of available nesting beaches are in public ownership; and (3) all the identified recovery tasks necessary to prevent extinction or irreversible decline have been successfully implemented [5].

[1] Turtle Expert Working Group. 2000. Assessment Update for the Kemp’s Ridley and Loggerhead Sea Turtle Populations in the Western North Atlantic. U.S. Dep. Commerce. NOAA Tech. Mem. NMFS-SEFSC-444, 115 pp.
[2] U.S. Fish and Wildlife Service. 2003. 12-month finding on a petition to list the Northern and Florida Panhandle loggerhead sea turtle (Caretta caretta) subpopulations as endangered. U.S. Fish and Wildlife Service. Federal Register (68:53947).
[3] Hawkes, L.A., A.C. Broderick, M.H. Godfrey, and B.J. Godley. 2005. Status of nesting loggerhead turtles Caretta caretta at Bald Head Island (North Carolina, USA) after 24 years of intensive monitoring and conservation. Oryx 39(1):65
[4] National Marine Fisheries Service Southeast Fisheries Science Center. 2001. Stock assessments of loggerhead and leatherback sea turtles and an assessment of the impact of the pelagic longline fishery on the loggerhead and leatherback sea turtles of the Western North Atlantic. U.S. Department of Commerce NOAA Technical Memorandum NMFSSEFSC-455, 343 pp.
[5] National Marine Fisheries Service and U.S. Fish and Wildlife Service. 1991. Recovery Plan for U.S. Population of Loggerhead Turtle. Washington, D.C. 64 pp.
[6] National Research Council. 1990. Population trends in Decline of the Sea Turtles: Causes and Prevention, pp. 42–50. National Academy Press, Washington, DC, USA.
[7] Fish and Wildlife Research Institute. 2006. Florida's Index Nesting Beach Survey Data. Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission. Available at (http://research.myfwc.com/features/view_article.asp?id=10690).
[8] Murphy, S and G. DuBose. 2005. Loggerhead turtle, Caretta caretta. South Carolina Department of Natural Resources fact sheet. Website (www.dnr.sc.gov/wcp/pdf/Loggerheadturtle.pdf) accessed December, 2005.

Banner photo © Phillip Colla