St. Eustatius Sea Turtle Conservation Programme - Annual Report 2005
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 hawksbills turtles.
Daily track surveys are carried out on Zeelandia Beach and Turtle Beach throughout the nesting season; the other nesting beaches are monitored sporadically. Every track is identified to species; categorised as a false crawl or a nest; all nest locations are recorded for inclusion in the nest survival and hatching success study.
- Track surveys were conducted from 5 April to 21 November; a total of 190 surveys were completed.
- Leatherback nesting activity occurred from 29 March – 22 June; 11 nests and eight false crawls were observed; all emergences were on Zeelandia Beach.
- Green turtles were recorded from 4 July – 1 October; 15 nests and 52 false crawls were encountered; nesting was on Zeelandia Beach, Turtle Beach and Kay Bay.
- Two hawksbill nests were observed on 27 May and 19 September; the first was on Kay Bay, the second on Zeelandia Beach.
Night patrols are only conducted on Zeelandia Beach due to limited personnel and minimal nesting on other beaches; patrols run from 9.00pm – 4.00am. 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.
- Night patrols were conducted from 18 April – 20 October; 165 patrols were completed, totalling over 1,000 hours of monitoring.
- Three leatherbacks and five green turtles were encountered during patrols; all were tagged by the Programme Co-ordinator.
- One of the green turtles was carrying a tag that had originally been applied in August 2002; this was the first record of a remigrant turtle for the project.
Average carapace measurements for females nesting in 2005:
- Leatherback: Curved carapace length (CCL) = 148.2cm; Curved carapace width (CCW) = 111.6cm
- Green: CCL = 108.8cm; CCW = 100.0cm
- No hawksbill turtles were encountered during night patrols.
All marked nests were included in a study of nest survival and hatching success. During track surveys they are monitored for signs of disturbance or predation; close to the expected hatching date observers record signs of hatchling emergence. Two days after tracks have been recorded the nest is excavated to determine hatching and emerging success.
- 28 nests were marked; 11 leatherback, 15 green and two hawksbill
- Two nests were lost during the incubation period; one leatherback nest was washed away during high tides and one green turtle nest was buried underneath a cliff fall.
- Incubation period for leatherbacks was 60 days, for greens 58.6 days and for hawksbills 63 days.
Excavations were performed on 20 nests; eight leatherback, 10 green and 2 hawksbill.
- Average egg chamber depth varied greatly between the three species; leatherback = 73.5cm, green = 57.5cm and hawksbill = 44.5cm
- Mean clutch size for each species; leatherback = 77.8 yolked + 48 yolkless eggs; green = 101.2 eggs and hawksbill = 147 eggs.
- Hatching success was greater for green nests than either hawksbill or leatherback; 76.8% compared to 41.1% and 3.5%, respectively.
- Emerging success was lower for leatherback nests than either hawksbill or greens; 2.1% compared to 41.1% and 70.1%, respectively.
- Very little predation was observed and few deformed embryos were recorded; one albino green turtle hatchling was encountered, and one green turtle egg contained twin embryos.
- One green turtle nest was relocated 25 days after it was laid, due to the risk of erosion; the eggs appeared relatively unaffected by the relocation, for when excavated the hatching success was 76.4%.
- In future years the practise of relocating nests laid in erosion zones to safer sections of the beach will continue.
A satellite tracking project was initiated in 2005 by the Dutch Caribbean Nature Alliance. This research was an inter-island collaboration of STENAPA and the Nature Foundation St Maarten. Dr Robert van Dam was the lead biologist, providing expertise and training in satellite telemetry methodology.
- Two transmitters were successfully deployed on nesting females; one on a green turtle from St Eustatius in September, the second on a hawksbill from St Maarten in October.
- The green turtle returned to nest once more after the transmitter was attached; she then remained in the near-shore waters of the island, less than 5km from the release site on the Atlantic coast. This may be the first record of an adult green turtle female being resident in her breeding area. Transmissions ended on 15 November, 2005.
- The hawksbill turtle migrated over 350km; she travelled to the British Virgin Islands, before her transmissions stopped on 14 December, 2005.
- An extensive education programme was part of the project. Island schools were visited by the Programme Co-ordinator and students aged 5 – 13 were taught about satellite telemetry and its use in turtle conservation. Several newspaper articles were published, and radio interviews given; in addition an exhibit was organised at the local library.
- Two competitions were organised for students; for the “Name the Turtle” Competition students had to draw a picture of a turtle, write a story about a turtle or make a model turtle out of recyclable materials. 106 entries were received; three winners were chosen and they won various prizes, including the chance to pick the name of one of the transmitter turtles. A similar competition was held on St Maarten. The green turtle was given the name “Miss Shellie” and the hawksbill was called “Archy”.
- The “Where’s the Turtle?” Competition had students guessing where the turtles would go on their migrations, and how far they would swim. The winners will be informed early in 2006.
Beach erosion continued on Zeelandia Beach in 2005:
- Many of the numbered marker stakes were lost from 2004, due to high tides.
- Over 20% were more than 2m from their 2004 location, suggesting extensive cliff erosion.
- Sand mining compounds the erosion problem at the northern end of Zeelandia Beach. Despite being an illegal activity it occurred throughout 2005, in the gulley and on the beach
- Five major cliff falls were recorded; each month from June – October.
- Monitoring of erosion will be a priority for 2006.
Several different community activities were conducted in 2005:
- A puppet show was organised for local schools and the after school programme to teach about several threats to turtles, and how they could be avoided.
- Presentations on turtles were given at the Auxiliary Home and the Methodist church.
- STENAPA participated in the School Vacation Programme; Antonio Flemming assisted with night patrols in his second year of the project.
Six beach clean-ups were conducted on Zeelandia Beach. A total of 12 trucks full of rubbish bags were removed in addition to a fridge, large rope, fishing net and car batteries. Unfortunately support from the local community in these events was disappointing.
The Sea Turtle Conservation Programme was featured in regular articles in the local press and on the radio. The STENAPA quarterly newsletter included two features about the research activities conducted in 2005 and the website contains several pages dedicated to the programme, with a focus on the Sea Turtle Satellite Tracking Project 2005.
Staff participated in several regional and international meetings in 2005:
- The 2004 Programme Co-ordinator attended the 25th International Sea Turtle Symposium in Savannah, Georgia, USA, 16 – 22 January 2005 and the WIDECAST Annual General Meeting. A teacher from the high school and a student also travelled to the symposium.
- The 2005 Programme Co-ordinator was invited to a workshop in Cuba; the focus of this meeting was to discuss the role of community involvement in sea turtle conservation projects. She gave a presentation about the programme on St Eustatius.
- In October the Programme Co-ordinator gave a lecture as part of the “Sea & Learn on Saba” event; the work of the Sea Turtle Conservation Programme was presented to international biologists, tourists and local residents.
Several recommendations were made for the 2006 season:
- Continued participation of volunteers, from Working Abroad and the STENAPA Intern Programme.
- Monitoring of nesting beaches to continue; daily track surveys on all beaches and night patrols of the primary nesting beach.
- Further development of the research programme; expand the focus of the programme by implementing an in-water survey of juvenile turtles and continue the satellite tracking project, with the possible inclusion of leatherback turtles.