Fall and Rise of Nesting Green Turtles (Chelonia mydas) at Aldabra Atoll, Seychelles: Positive Response to Four Decades of Protection (1968–2008)

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.