St. Eustatius Sea Turtle Conservation Programme - Annual Report 2008
The St Eustatius Sea Turtle Conservation Programme was initiated in 2001 due to concerns that the island’s sea turtle populations were being threatened due to habitat degradation and destruction. The programme is managed by St Eustatius National Parks Foundation (STENAPA), which is the main environmental non-governmental organization on the island.
The Sea Turtle Conservation Programme is affiliated to the Wider Caribbean Sea Turtle Conservation Network (WIDECAST) and adopts its monitoring and tagging protocols.
Since monitoring began, three species of sea turtles have been confirmed nesting on the island; leatherback (Dermochelys coriacea), green turtle (Chelonia mydas) and hawksbill (Eretmochelys imbricata). There was an unconfirmed nesting by a fourth species, the loggerhead (Caretta caretta), in 2004.
Five nesting beaches have been identified; Zeelandia Beach, Turtle Beach, Lynch Bay, Oranje Bay and Kay Bay. Zeelandia Beach is the primary nesting beach, and the only place where all three species nest regularly; the other beaches are used occasionally by green and hawksbill turtles.
Morning track surveys are carried out on Zeelandia Beach and Turtle Beach throughout the nesting season. The other nesting beaches were monitored weekly. Every track is identified to species; categorised as a false crawl, activity or a nest; all confirmed nests are included in the nest survival and hatching success study.
- Morning track surveys were conducted daily from 13 March to 6th November; a total of 238 index beach morning surveys were completed.
- 20 confirmed leatherback nests (from deposition observation or excavation proof) were recorded from 13th March – 14th June on Zeelandia Beach (stakes 1-17); in addition, four probable lays and two false crawls were recorded.
- Green turtles were recorded from 26 July until 14th October; 46 Activities were recorded including 1 confirmed nest, 14 probable lays and 31 false crawls.
- Hawksbill turtles were observed from the 8th of April until 10th of September. A total of nine activities were recorded. Four were potential nests and 5 were tracks only.
Night patrols are only conducted on our index beach, Zeelandia to Turtle Beach due to limited personnel and minimal nesting on other beaches; patrols run from 9:00pm – 03:30am. Each turtle encountered is identified to species; tagged with external flipper tags and an internal PIT tag (leatherbacks only); standard carapace length and width measurements are taken; nest locations are recorded for inclusion in the nest survival and hatching success study.
- Targeted night patrols were conducted from 24th March – 05 October; 74 patrols were completed, totalling 499.5 hours of monitoring.
- 19 leatherback, 1 hawksbill and 5 green turtles were seen giving a 32% encounter rate.
- Five individual leatherbacks were observed during patrols; all received external flipper tags and 3 received PIT tags. Biopsy samples were taken from these turtles.
- Leatherback 133713290A, observed on 12th of May was originally tagged by STENAPA in 2002, again in 2004 and received new flipper tags in 2008. Leatherback 023*359*883 also received new flipper tags; this turtle was originally tagged in Trinidad and Tobago 2005.
- No hard shell species were tagged or observed nesting during the 2008 season.
Average carapace measurements for female Leatherbacks nesting in 2008:
- Leatherback: Curved carapace length (CCL) = 156.1 cm; Curved carapace width (CCW) = 115.6 cm.
- No Greens or Hawksbills were measured for fear of disturbance in 2008.
All located leatherback nests were included in a study of nest survival and hatching success. During morning track surveys false crawls and probable nests were marked. Close to the expected hatching date the observers recorded signs of hatchling emergence. Two days after hatchling tracks had been recorded the nest was excavated to determine hatching and emerging success.
- Only the confirmed leatherback nests were included in this study.
- All probable hard-shell nests were lost due to storms, swash and flooding.
- Mean incubation period for leatherbacks was 69 days.
Excavations were performed on 14 nests; 13 leatherback and the unmarked green nest. Many nests could not be found for excavation purposes.
- Average egg chamber depth was 77.8 cm for the leatherback and one green nest = 47cm.
- Mean clutch size for leatherback = 79 yolked + 35.8 yolkless eggs and the green nest = 116 yolked + 0 yolkless eggs.
- Nine nests hatched or partly hatched out of 13 excavated Leather back nests, 4 were unsuccessful nests.
- Leatherbacks showed a very low mean hatching success rate at 7.27% of the 13 excavated nests and 41.81% emerging success in 2008.
Turtle incidents amounted to one injured and four dead turtles in 2008, the highest annual number since commencement of the turtle conservation program.
- On Sunday, the 23rd of March, an Olive Ridley (Lepidochelys olivacea ) was found dead entangled in a net at Lynch bay by local citizens of Saint Eustatius. This has been the first confirmed presence of an Olive Ridley turtle in Statian waters.
- A small green turtle was observed by the Marine Park Manager and turtle intern on the 27th of April at 16:00 when returning from a dive. The injured turtle was seen on the surface just outside of the harbour pier and appeared to be stuck on the surface.
- On April 28th a small (10-50cm) suspected green turtle was found by Alain Beurgur (Scubaqua) at STENAPA reef during a night dive and was described to be cut in half. The Marine Park Manager and the Turtle intern were informed the next morning and immediately inspected the site. No turtle was found and it is suspected that the carcass had been taken by a shark during the night.
- The Marine Park Manager was alerted on the afternoon of July 6th to the presence of a stranded Hawksbill Turtle just out from the Twelve Guns snorkel site. On arrival Mr. Munson was greeted by Mr. Van Duren and was shown the turtle, which was deceased being severely tangled in green fishing net with no noticeable lacerations or body damage.
- On the morning of 13th of September 2008, The Marine Park Manager accompanied by a STENAPA volunteer came across a dead Hawksbill at Lynch Beach. Biometrics were taken and the animal showed no obvious cause of death.
Beach erosion continued on Zeelandia Beach in 2008:
- Many of the numbered marker stakes were lost due to high tides. Approximately 30 were replaced in March and the beach re-staked.
- Beach mapping and erosion monitoring continued this year. Data were collected in March, July, September and October.
- Sand mining compounded the erosion problem at the northern end of Zeelandia Beach. One summons was issued by STENAPA and fine paid by accused sand miner.
- An estimated 20 tonnes of sand was taken from Zeelandia (at stake 14) from the 24th March to 2nd of November.
- Beach protection efforts continued with the placement of massive boulders in front of a primary access point for sand miners.
- Approximately 18 cliff falls were recorded from April to October.
Various community activities were conducted in 2008:
- During July 2008, STENAPA conducted its second Summer Club for four sessions each week. A total of forty children aged eight to 13 signed up for the club which included hiking, snorkeling and turtle education activities. STENAPA’s Summer Club turtle education program ran from 2 July to 2 August every Tuesday and Thursday.
Twelve extensive beach clean-ups were conducted on our index beach, Zeelandia during Family Friday volunteer activities. The September cleanup coincided with Ocean Conservancy’s International Coastal CleanupTM Campaign on 20th September. Twelve large garbage sacks of itemized plastic, cans, rope, Styrofoam and a huge fishing net were collected on this particular cleanup. Beach cleanups were carried out by the Marine Park Manager, STENAPA staff and interns, Working Abroad volunteers, local citizens and BroadReach volunteers.
- A total of 17 trucks full of rubbish bags were removed from the islands’ beaches.
- During EnviroWeek in the week of 16 October the Junior Rangers, led by Parks Ranger Hannah Madden, conducted a cleanup on Lynch beach and Venus Bay. A number of island clean ups were carried out by local children in our education programs: Snorkel club and Junior Rangers.
The Sea Turtle Conservation Programme was featured in regular articles in the regional press, television and on the local radio. The STENAPA quarterly newsletter included several features about the research activities conducted in 2008. The STENAPA website contains several pages dedicated to the programme. The island videographer Dwight Barran was alerted to the beach on two occasions to video tape a nesting leatherback for local television. Reporters/dive magazine photographers also joined on a few occasions to witness and photograph nesting events.
The turtle conservation programme continued generating interest from the local population of St. Eustatius. The Marine Park Manager spoke with several interested members of the public who were keen to view the nesting activity of a turtle, nest exhumation or a hatchling release. The turtle phone was filled with a list of interested people to contact when there were possibilities for seeing turtles. This approach was very popular and a grassroots approach of connecting with marine turtles. In 2008 a total of 40 islanders and tourists joined the night patrols. Other interested Statians were called to the beach when a turtle was nesting.
Staff participated in several regional and international events in 2008:
The Marine Park Manager, Lee Munson, accompanied by the Office Administrator/Marine Park Assistant, Jessica Berkel attended a Turtle Research and Management techniques Course between October 13th – 18th, on Bonaire. Both Lee and Jessica, together with Manager, Nicole Esteban, attended the WIDECAST Annual General Meeting held on St Kitts from December 18th - 20th .
In April 2008, STENAPA welcomed its second Marine Turtle Intern, Joseph Roche to St Eustatius. Joe had previous experience working with marine turtles, especially leatherback turtles, in 2006 in Gandoca, Costa Rica. His duties included organizing the turtle aspect of the STENAPA Summer Club, coordinating beach cleanups, beach mapping and managing the data, as well as night patrols, tagging, morning beach surveys and habitat survey dives. Unfortunately Joe terminated his internship half way through the season. His partial replacement was Gerdijanne Leestemaker, our main island turtle volunteer from Holland who has shown a huge commitment and passion for nesting turtles. She has been invaluable to the success of the 2008 nesting program and has assisted in other areas at STENAP A.
In March 2008, the Zeelandia beautification project continued. The primary objective was to deter vehicles from driving on the beach, stop sand mining and prevent further erosion. A Family Friday was dedicated to replanting of palm trees and yucca plants that succumbed to the warm weather. Only a few of these plants took root and have established themselves at Zeelandia. The information signs placed at Zeelandia were routinely inspected and cleaned. The purpose of these signs is to educate the public about turtles that nest on the beach and remind people not to drive on the beach. In 2008 the prime access point to the beach was blocked by way of huge boulders donated from a nearby construction site. This barrier offers limited protection as other access points still allow sand miners the opportunity to venture on to the beach. Our presence on the nesting beach at night dramatically reduces the instances of sand mining at Zeelandia.
Surveys for the In-Water Monitoring of Sea Turtle Aggregations in St Eustatius National Marine Park began in January 2008 in order to assess the current status and distribution of foraging turtle aggregations in the surrounding waters of St Eustatius. The foraging population is formed of greens, Chelonia mydas, and hawksbills, Eretmochelys imbricata. 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 harbours 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.
Several recommendations are made for the 2009 season:
- Continued participation of volunteers, from Working Abroad and the STENAPA intern Programme. Limit beach patrols to 4 additional people.
- Foster public awareness of the Turtle Programme within the island of St Eustatius and the Netherlands Antilles. Introduce the new intern on the radio along with the 2009 nesting season and activities for interested members of the community.
- Continue with STENAPA Summer Club and have the Turtle Education activities integrated into a fundamental component.
- Monitoring of nesting beaches to continue: daily track surveys on all beaches and effective night patrols of the primary nesting beach.
- Further development of the research programme: Introduce an experimental hatchery in the “SAFE AREA” described in this report and monitor for hatching success.
- Compare hatching success data with neighbouring islands such as St Kitts.
- Strongly focus on relocating nests to the hatchery that may be exposed to swash, erosion, cliff fall, sand mining, runoff, and pollution.
- A proposal to extend the satellite tracking to leatherback turtles for DCNA.
- Continue with grant proposals that are necessary to finance equipment and activities of this programme.
- Monitoring of the water table at Zeelandia beach should be a priority in 2009 to determine if the subterranean water levels are causing possible egg failure but more importantly accelerating possible beach erosion.
- Continue to develop the Zeelandia Beautification Project to include a revamp of the concrete turtle, signage, plantation and possible picnic area for individuals interested in the beauty of Zeelandia Beach.
- Make additions to the boulder barriers to deter vehicles from venturing on to the beach and organise for them to be painted during summer club.
- Continue with the beach mapping project and make conclusions from comparisons with previous years.
- Revitalize the in-water turtle sighting surveys with the local diving centres. This information will help make more informed decisions regarding the in-water monitoring programme.
- Continue the in-water survey including night surveys and feeding behaviour investigations. o Continue with tissue sampling and arrange samples for processing.
- Improve on nest marking from 2008 with more accurate triangulation, nest marking tape and a protocol that remains continuous throughout the season.
- Approach NuStar energy and encourage a switch from white to red light for all East facing lights. This is also something to request for the lighting at the buildings that face Zeelandia beach.