Seychelles sea turtles
Sea turtles
Two species of sea turtle nest in Seychelles: the green turtle Chelonia mydas and the hawksbill turtle Eretmochelys imbricata. In addition loggerhead Caretta caretta, leatherback Dermochelys coriacea and olive Ridley turtles Lepidochelys olivacea have occasionally been recorded in Seychelles waters but do not nest. All turtles are protected by law in Seychelles but poaching does continue. Nesting beaches are currently threatened by development although numbers are increasing in protected areas (mostly nature reserves).
Nature Protection Trust of Seychelles monitored the turtles nesting on the beaches of Silhouette island from 1997. Some of the main beaches used by turtles are difficult to reach and so monitoring effort varied over the years. Monitoring came to an end in 2010 with the closure of our Silhouette project.
Monitoring methods
On the east side of Silhouette all beaches are easy to reach and are visited regularly by island residents and visitors who reported nesting turtles. The main nesting beach is at Grande Barbe, due to its isolation this is harder to reach. No data were gathered in 1997-1998, in 1999-2003 only single visits were made during the nesting season, in 2003-4 and 2008-9 data were based on single counts of nests found half-way through the season, and 2007-8 was based on a complete count of the first half of the season. Compete counts were made for 2004-8. In order to estimate the total number of nests for other years the daily number of nests for the 2004-8 data were used to determine an average nesting pattern, producing a mean nesting rate for each week of the nesting season for hawksbill turtles (too few green turtles were recorded to generate a model). Pointe Etienne is a small beach but is used by a large number of turtles, this is only accessibly occasionally and all nests were counted and the total seasonal nesting estimated using the same method as at Grande Barbe. For this site systematic data were only collected in 2006-7 and 2007-8.
Monitoring results
See the 2009 NPTS scientific report for turtle monitoring - download here
Turtle tagging
Most turtle monitoring projects tag nesting turtles but we did not tag turtles on Silhouette, preferring to leave the animals undisturbed. The small number of tagged animals seen were recorded:
| Left tag | Right tag | Nested | Origin |
| SEY 425? | SEY 4255 | 2004-5 at Anse Patates | Cousine |
| ? | scar | 2004-5 at Grande Barbe | |
| clips but no tag | 2004-5 at Grande Barbe | ||
| ? | ? | 2004-5 | |
| - | scar | 2005-6 at Grande Barbe | |
| SEY 2601 | SEY 2602 | 2006 (twice) at Grande Barbe | Cousine 1997 |
| SEY 6942 | ? | 2006 at Grande Barbe | Cousine 2003 |
| SEY ???2 | SEY 6943 | 2006 at Grande Barbe | Cousine 2003 |
| SEY 2863 | SEY 2862 | 2006 at Grande Barbe | North |
| - | 1756 | off-shore | Aldabra 1996 |
Hatching success
In recent years hatching success has been reduced at the La Passe side of the island due to increased development. In 2006 lights at the newly developed hotel attracted hatching turtles inland, away from the sea. Several hundred were rescued from the garden and from a marsh, but many others died in the lights or caught by crabs. In 2007 we designed a special turtle box which can be placed over the nest just before it is due to hatch. This blocks out all light on three sides and the top, leaving only the light reflecting on the sea visible to the hatchlings. As a result only 3 baby turtles needed rescuing in the 2008-9 season. |  |
