Loggerhead turtle Caretta caretta density and abundance in Chesapeake Bay and the temperate ocean waters of the southern portion of the Mid-Atlantic Bight
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We conducted aerial surveys of sea turtles in 2011 and 2012, incorporating corrections for perception and availability bias in Chesapeake Bay and near-shore continental shelf waters of the Mid-Atlantic Bight off the US states of Virginia and Maryland. Results of these surveys and ancillary research to determine surface times for loggerhead turtles provide us with a new baseline population estimate for turtles in the region. Prior surveys were conducted in Chesapeake Bay in the mid-1980s and early 2000s, and in ocean waters in the late 1970s and early 1980s. Although comparison of density estimates not corrected for availability between prior surveys and this effort suggests that the population of sea turtles, especially loggerhead turtles, is higher than previous estimates, differences between surveys may be the result of survey methodologies and cannot be assumed to be true changes in density. Surface time for availability corrections was calculated using dive summaries from satellite telemetry on 27 loggerhead turtles tracked between 2011 and 2015. We calculated stratified seasonal availability corrections for bay and ocean waters based on assumed differences in turtle behavior and water clarity between the 2 habitats. For each habitat, we provided seasonal corrections for 3 detection depth bins (shallow, moderate, and deep) to account for differences in sub-surface detection ranges. Differences and trends toward differences among availability corrections underscore the need to better understand the many variables that affect surface time for sea turtles in temperate waters, and the effect that availability has on abundance and density estimates.
Barco , S G , Burt , M L , DiGiovanni , R A , Swingle , W M & Williard , A S 2018 , ' Loggerhead turtle Caretta caretta density and abundance in Chesapeake Bay and the temperate ocean waters of the southern portion of the Mid-Atlantic Bight ' Endangered Species Research , vol. 37 , pp. 269-287 . DOI: 10.3354/esr00917
Endangered Species Research
Copyright © The authors 2018. Open Access under Creative Commons by Attribution Licence. Use, distribution and reproduction are unrestricted. Authors and original publication must be credited.
DescriptionFunding was provided by the NOAA Species Recovery Grants to States program (Award #NA 47200033) issued to the Virginia Department of Game and Inland Fisheries which contracted with the Virginia Aquarium & Marine Science Center Foundation. Additional funding for tags and turtle capture was also provided by US Fleet Forces Command as well as the Virginia Aquarium Batten Collaborative Research Fund and Batten Professional Development Fund.
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