ESR 31:211-225 (2016)  -  DOI: https://doi.org/10.3354/esr00765

In-water assessments of sea turtles at Glover’s Reef Atoll, Belize

Samantha Strindberg1,*, Robin A. Coleman2,4, Virginia R. Burns Perez2, Cathi L. Campbell1,5, Isaias Majil3, Janet Gibson2

1Wildlife Conservation Society, Global Conservation Program, 2300 Southern Blvd., Bronx, NY 10460, USA
2Wildlife Conservation Society, Global Conservation Program, PO Box 768, 1755 Coney Drive, 2nd Floor, Belize City, Belize
3Belize Fisheries Department, Princess Margaret Drive, PO Box 148, Belize City, Belize
4Present address: Sawfish Consulting Ltd., 31 Santa Maria Street, Belmopan City, Belize 5Present address: Archie Carr Center for Sea Turtle Research, Department of Biology, University of Florida, Gainesville, FL 32611, USA
*Corresponding author:

ABSTRACT: The decline of sea turtle populations in the Caribbean has led to intensive recovery efforts. In Belizean waters, hawksbill turtles are seemingly making a comeback. At Glover’s Reef Atoll particularly, juvenile hawksbill turtles are found in the fore-reef habitat. The population status and dynamics of this foraging aggregation were assessed to inform conservation management and to ascertain the national and regional importance of this site. During 12 sampling periods from 2007 to 2013, turtles of all species were counted, captured, and tagged. For hawksbill turtles, the capture-recapture histories were combined with the counts using a mark-resight analysis under a robust design. This provided estimates of abundance as well as survival and transition rates. From 2009 onward, distance sampling was also used to estimate density and abundance of hawksbill turtles and the less frequently encountered green and loggerhead turtles. Distance sampling provided a more cost-effective estimation method for multiple species and another more precise source of abundance estimates for hawksbills. This is the first study known to use either mark-resight or distance sampling methods during snorkel surveys of sea turtles. It produced reasonably congruent abundance estimates of >1000 juvenile hawksbills and an order of magnitude less of green and loggerhead turtles. The mark-resight analysis estimated an apparent juvenile hawksbill survival probability of 0.975 (95% CI: 0.936-0.99), indicating that mortality factors are low. The Atoll provides important developmental habitat for juvenile hawksbills, contributing to the recovery of the species on the national and regional scale.


KEY WORDS: Hawksbill turtle · Green turtle · Loggerhead turtle · Distance sampling · Mark‑resight · Glover’s Reef Atoll · Belize · Caribbean


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Cite this article as: Strindberg S, Coleman RA, Burns Perez VR, Campbell CL, Majil I, Gibson J (2016) In-water assessments of sea turtles at Glover’s Reef Atoll, Belize. Endang Species Res 31:211-225. https://doi.org/10.3354/esr00765

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