Estimates of marine turtle nesting populations in the south-west Indian Ocean indicate the importance of the Chagos Archipelago

• DOI: 10.1017/s0030605319001108
• Publication Date: 2020-02-10T09:01:23Z
• Authors: Jeanne A. Mortimer; Nicole Esteban; Antenor Nestor Gu...; Graeme C. Hays
• Keywords: Archipelago; Atoll; Sea turtle

Abstract Global marine turtle population assessments highlight the importance of south-west Indian Ocean region, despite data gaps for Chagos Archipelago. The archipelago hosts nesting hawksbill Eretmochelys imbricata and green turtles Chelonia mydas, both heavily exploited 2 centuries until protection in 1968–1970. We assessed available habitat spatial distribution activity during rapid surveys 90% archipelago's coastline 1996, 1999, 2006 2016. quantified seasonality mean annual egg clutch production from monthly track counts 2006–2018 along a 2.8 km index beach on Diego Garcia island. An estimated 56% (132 km) provided suitable habitat. Peros Banhos atolls accounted 90.4% 70.4% nesting. Hawksbill showed distinct peaks October–February, nested year-round with elevated June–October. Estimates 6,300 20,500 clutches laid annually 2011–2018 indicate that Archipelago has increased 2–5 times 4–9 since 1996. Regional estimates produce 10 more than turtles, accounts 39–51% an 12,500–16,000 14–20% 104,000–143,500 Ocean. improved status may reflect > 40 years without significant exploitation. Long-term monitoring is needed to captureinterannual variation numbers minimize uncertainty estimates.