Alabama Sea Turtles

A project of USGS Alabama-NRDA Sea Turtles in conjunction with the partners and sponsors detailed below.

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Introduction

Northern Gulf of Mexico (NGoM) loggerheads (Caretta caretta) make up one of the smallest subpopulations of this threatened species and have declining nest numbers. Declines in nest abundance for the NGoM subpopulation may be attributed to several factors, such as commercial fisheries and oil pollution. Little is known about nest site fidelity, movements, or locations of in-water inter-nesting habitat for loggerheads in the Northern Gulf of Mexico.

We used satellite telemetry and a switching state-space model to identify distinct foraging areas used by 59 NGoM loggerheads tagged during 2010–2013. We tagged turtles after nesting at three sites, 1 in Alabama (Gulf Shores; n = 37) and 2 in Florida (St. Joseph Peninsula; n = 20 and Eglin Air Force Base; n = 2). After displacement from nesting beaches, to date (July 31, 2014) 44 turtles traveled to foraging sites where they remained resident throughout tracking durations; the remaining turtles were either not tracked long enough to determine foraging site, or their transmissions ceased abruptly (i.e., off Cuba). Selected foraging locations were variable distances from tagging sites, and in 5 geographic regions; no turtles selected foraging sites outside the Gulf of Mexico (GoM). Foraging sites overlapped with known trawling activities, oil and gas extraction activities, and the footprint of surface oiling during the 2010 Deepwater Horizon oil spill (n = 10). Our results highlight the year-round use of habitats in the GoM by loggerheads that nest in the NGoM. Our findings indicate that protection of females in this subpopulation requires both international collaborations and management of threats that spatially overlap with distinct foraging habitats.

We would like to thank the U.S. Fish and Wildlife Service and the Share The Beach volunteers for assistance on this project. This telemetry data was generated as part of the ongoing Deepwater Horizon Natural Resource Damage Assessment (publicly available from www.seaturtle.org).