Research and Monitoring of Bonaire ’s Sea Turtles: 2014 Technical Report
Sea Turtle Conservation Bonaire (STCB) was initiated in the early 1990s to protect the island’s marine turtle populations. Our current research and monitoring efforts, which were standardized more than a decade ago, include monitoring nesting beaches around Bonaire, conducting intensive in-water netting and snorkel surveys (capture-mark-recapture), and tracking post-breeding migration using satellite telemetry. These techniques provide us with a better understanding of Bonaire sea turtles’ breeding success, abundance, health, growth rates, migratory paths and distant feeding grounds, residency duration, habitat quality, and threats.
During the 2014 season, we recorded 63 nests at our index beach on Klein Bonaire. Total hawksbill (45) and loggerhead (18) nests documented there were similar to numbers observed during recent years. Across Bonaire and Klein Bonaire, we observed three species crawling 260 times, including 83 confirmed or suspected nests. Only two green turtle nests were recorded in northeastern Bonaire, whereas hawksbills and loggerheads exclusively nested on Klein Bonaire and the beaches of southern Bonaire. Total nesting activities peaked during June through August, with nesting extending through December.
We documented a much higher number of false crawls (unsuccessful nesting attempts) for both hawksbills and loggerheads in 2014 than in 2013. This phenomenon may result from a small number of individuals which were inefficient nesters (i.e., false crawled multiple times before successfully laying a nest), disturbance to turtles during nesting, and / or indicate deterioration in the quality of particular nesting sites, perhaps due to factors such as removal of vegetation. Estimates of clutch size and hatch success suggest that nearly 8,700 turtles hatched on the beaches of Bonaire and Klein Bonaire during 2014, including some 6,300 hawksbills, 2,200 loggerheads and 160 green turtles.
During in-water snorkel surveys, we observed and captured green turtles and hawksbills in all regions sampled, including Klein Bonaire, along the west coast of Bonaire, and near the reef bordering Lac. Netting in Lac and Lagoen resulted in a record number of captures during 2014, primarily green turtles. The aggregation of green turtles near Lac remains much larger than sites along the west coast, and greens captured there were bigger than conspecifics elsewhere, perhaps a result of the composition and high densities of sea grasses in Lac. Analysis of the 2013 and 2014 capture data from Lac indicates that netting during the second week of a two-week session is less efficient at capturing turtles. These results suggest that conducting netting sessions during non-consecutive weeks may be a more effective sampling strategy.
We received reports from the WIDECAST Marine Turtle Tagging Centre of 5 green turtles caught in nets by Nicaraguan fishers in the sea turtle harvest during the past 18 months. These recoveries provide invaluable information about international movements and migratory behaviors. The prevalence of fibropapillomatosis (FP) among green turtles captured in and near Lac again increased in 2014, as roughly one-third of all captures were observed with external tumors. However, we recaptured two green turtles that were previously treated to eliminate the fibropapilloma tumors. In both cases, the results were positive, perhaps suggesting that removing tumors via surgery or ligation can improve the health of individual turtles and reduce the incidence of FP in Lac.
Retreived from http://www.bonaireturtles.org on April 13, 2015