In-water monitoring of sea turtle aggregations in St. Eustatius National Marine Park

Abstract:

All species of sea turtles in the Caribbean have come under threat in recent years due to a multitude of factors. Habitat destruction and modification are playing a larger and larger role in current population declines. Trends projected from data of nesting females are useful in predicting potential shifts in populations, but such changes may not appear in adult female populations until it is too late to protect them. Changes in the populations of juveniles are a much earlier and more accurate indicator to assess the future of the population as a whole. In-water surveys of sea turtle foraging grounds are the best tool to monitor such changes in juvenile and sub-adult populations so that they can be more quickly and effectively protected.

In-water surveys began in the Statia National Marine Park in January 2008 in order to asses the current status and distribution of foraging turtle aggregations (greens, Chelonia mydas, and hawksbills, Eretmochelys imbricata) in the surrounding waters. Surveys yielded a total catch per unit effort (CPUE) of 1.17 turtles per hour, with an average CPUE of 0.67 for greens and 0.50 for hawksbills. Greens and hawksbills were found to occupy different areas in different densities, with more greens in the less protected sea grass beds of the harbors and more hawksbills on the reefs of the reserves. Size and gender data indicate a healthy juvenile and sub-adult population for both species. Future monitoring is needed to assess any changes in this population, and active protection of the foraging grounds of these species is essential to their continued existence within the marine park.