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1 December 2011 Fall and Rise of Nesting Green Turtles (Chelonia mydas) at Aldabra Atoll, Seychelles: Positive Response to Four Decades of Protection (1968–2008)
Jeanne A. Mortimer, Rainer G. von Brandis, Anna Liljevik, Roselle Chapman, John Collie
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Abstract

When Aldabra Atoll became a nature reserve in 1968, its endangered nesting green turtle (Chelonia mydas) population was the first to be protected in the Indian Ocean. In 1983, Aldabra became a UNESCO World Heritage Site managed by the Seychelles Islands Foundation (SIF). But prior to 1968, its green turtles suffered intense exploitation documented by trade statistics, historical literature, and a scientific study in 1927. Three population surveys conducted just before, during, and shortly after 1968 provide baseline data by which to assess the long-term population recovery monitored since 1980 using a standardized track count protocol. The 52 nesting beaches distributed along the 83-km outer rim of Aldabra were classified into 6 beach groups (WGT, SETT, DDM, DJL, CC, and North), with total beach length of 5.2 km. During Phase 1 (1980–1994) of the study, 17 index beaches (WGT #1–17) were monitored 4 times per month and other beaches opportunistically. During Phase 2 (1994–2008), index beaches (WGT #1–22 and SETT) were monitored at least 4 times per month and remote beaches monthly. Track counts were converted to estimated egg clutch production using nesting success data. Reproductive output for the atoll rose from a mean annual estimated 2000–3000 clutches in the late 1960s to 15,669 (SD  =  2776) during 2004–2008, equivalent to a mean estimated 3100–5225 females nesting annually (assuming an average of 3–5 egg clutches per female). This represents a 500%–800% increase during 40 years of complete protection. During Phase 2, the rate of increase was highest at the Settlement Beach (SETT), which had historically suffered the most intense exploitation.

Chelonian Research Foundation
Jeanne A. Mortimer, Rainer G. von Brandis, Anna Liljevik, Roselle Chapman, and John Collie "Fall and Rise of Nesting Green Turtles (Chelonia mydas) at Aldabra Atoll, Seychelles: Positive Response to Four Decades of Protection (1968–2008)," Chelonian Conservation and Biology 10(2), 165-176, (1 December 2011). https://doi.org/10.2744/CCB-0872.1
Received: 20 June 2010; Accepted: 1 June 2011; Published: 1 December 2011
KEYWORDS
Cheloniidae
Indian Ocean
nesting trends
population assessment
Reptilia
Testudines
track counts
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