Hawksbill and Green Turtle Abundance Estimates from Chagos Archipelago

A collection of abundance estimates for immature hawksbill and green turtles in a tidal lagoon, derived from a multi-method study. The study captured and marked 50 turtles and used satellite tracking data from 27 turtles to estimate a total population of 339 turtles, with densities ranging from 265 to 499 turtles per square kilometer. The research was conducted by Holly Stokes of Sea Turtle Conservation and published in 2026.

Use Cases

• Compare hawksbill turtle density estimates (265-499 turtles km-2) from this site against other global foraging locations.
• Analyze the proportion of hawksbill (84%) versus green turtle (16%) populations within the lagoon's total abundance estimate of 339 turtles.
• Model population dynamics using the count of 50 marked turtles and satellite tracking data from 27 turtles to refine resighting and emigration probabilities.
• Assess the effectiveness of long-term protection by examining the reported high hawksbill density relative to 17 other global foraging sites.

Strengths

• Provides a total abundance estimate of 339 turtles with a specific density range (265-499 turtles km-2).
• Integrates data from three distinct methodologies: UAV surveys, satellite tracking (27 turtles), and mark-recapture (50 turtles).
• Includes species-specific breakdowns, reporting that 84% of the estimated population are hawksbill turtles and 16% are green turtles.

Limitations

• The dataset is focused on a single tidal lagoon in the Chagos Archipelago, limiting geographic generalizability.
• Sample sizes for the foundational capture-mark-recapture (50 turtles) and satellite tracking (27 turtles) components are relatively small.
• The data describes a specific point in time; longitudinal trends in abundance are not provided.

Provenance

Source

Dataverse, authored by Holly Stokes of Sea Turtle Conservation.

Collection Method

Combined UAV surveys, high-resolution satellite tracking (Fastloc-GPS), and catch-mark-recapture approaches.

Freshness

Data was last updated in January 2026.

Geography

Tidal lagoon in the Chagos Archipelago, Indian Ocean.