Abstract:
Three species of sea turtles are regular visitors to the waters surrounding Anguilla: Chelonia mydas; Eretmochelys imbricata; and Dermochelys coriacea. A small number of reports have also been made regarding Caretta caretta sightings, but none of these were confirmed with direct evidence. Biometric measurements of turtles sampled in Anguilla began in September 2002, with efforts increasing over subsequent years initially driven by a regional project funded across the UK overseas territories by the UK Foreign and Commonwealth Office and the UK Department for Environment Food and Rural Affairs. After the completion of this project, work continued under the leadership of the Department of Fisheries and Marine Resources (DFMR), Government of Anguilla. Today, the work load is shared with the Anguilla National Trust who lead land based turtle nesting beach surveys with the in-water work remaining under the lead of DFMR. A small number of reports have been produced over the years based on this work, but to date none of the biometric data has been analyzed. This report presents this data, combined with other previously unpublished information. Analysis found clear linear relationships between all biometric measurements taken, except turtle head width, possibly due to growth rate acceleration with age varying between sexes. This suggests that when measuring turtles during sampling, one single measurement may be made from which all other measurements (except head width) can be inferred. This may be beneficial when sampling nesting females susceptible to disturbance. The measurement suggested to be taken in these circumstances for later extrapolation is curved carapace length (CCL) due to simple equipment needs and ease of measure. Growth rates were obtained via recapture measurements from seven individuals (four C. Mydas and three E. imbricata) which gave growth rates for C. Mydas of approximately 6 cm/yr-1 CCL with E. imbricata more variable at between 2-6 cm/yr-1 CCL. Fibropapilloma was first recorded on a C. mydas individual in June 2010, with no occurrences yet reported for E. imbricata. In 2014 and 2015, 31% and 17% of C. mydas individuals captured in Island Harbour showed signs of the virus respectively, with most cases exhibiting well-formed tumors. It is hoped that funding can be secured to expand the current turtle program allowing more frequent sampling, increased numbers of sampling sites, and initiation of GPS tracking studies. With the current moratorium on harvesting sea turtles due to end in 2020 it is essential that as much information is collected as possible on these species, thus allowing properly informed management decisions to be made.
