ESR 3:217-227 (2007)  -  doi:10.3354/esr003217

Reproductive seasonality and trend of Chelonia mydas in the SW Indian Ocean: a 20 yr study based on track counts

M. Lauret-Stepler 1,2,5,*, J. Bourjea2, D. Roos3, D. Pelletier4, P. G. Ryan1, S. Ciccione5, H. Grizel2

1Percy FitzPatrick Institute, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
2Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER), Rue Jean Bertho BP 60, 97822 Le Port Cedex, Ile de la Réunion
3Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER), blvd Jean Monnet BP 171, 34203 Sète Cédex, France
4Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER)/IRD BP A5, 98848 Nouméa Cédex, Nouvelle Calédonie
5Kelonia, L’Observatoire des Tortues Marines de La Réunion, BP 40, 97898 Saint Leu Cedex, Ile de la Réunion

ABSTRACT: The green turtle Chelonia mydas is classified as endangered because of global declines over the past few centuries due to human exploitation and habitat destruction, particularly the loss of nesting areas. We used the number of tracks as an indicator of breeding female abundance at their nesting sites to study the seasonality and trends of turtles breeding at 3 islands in the SW Indian Ocean: Europa, Tromelin and Grande Glorieuse, over 20 yr. On Tromelin, tracks were counted along the entire nesting beach, but on Europa and Grande Glorieuse counts were limited to a proportion of the island. Europa and Tromelin exhibited similar seasonal patterns, with a well-defined peak during the wet season (November–February), compared to a dry season peak for Grande Glorieuse (March–June). The main season was significantly longer on Grande Glorieuse (288 ± 43 d) than on Europa (218 ± 60 d), with Tromelin intermediate (252 ± 43 d). There was greater variation in the start of a season compared to the median and end at all sites throughout the study. Approximately 7178 ± 3053 (n = 19) tracks were recorded annually on the entire nesting beach on Tromelin, compared with 1480 ± 666 (n = 19) on 16% of nesting beaches on Grande Glorieuse and 1361 ± 903 (n = 23) on 26% of beaches on Europa. The number of tracks has increased significantly on Europa (3% yr–1) and Grande Glorieuse (6% yr–1). The increasing number of nesting turtles illustrates the effectiveness of conservation measures on sites formerly exploited by humans.


KEY WORDS: Green turtles · Chelonia mydas · Track count · Trend · Seasonality · Eparses Islands · Indian Ocean


Full text in pdf format
Supplementary appendix 
Cite this article as: Lauret-Stepler M, Bourjea J, Roos D, Pelletier D, Ryan PG, Ciccione S, Grizel H (2007) Reproductive seasonality and trend of Chelonia mydas in the SW Indian Ocean: a 20 yr study based on track counts. Endang Species Res 3:217-227

Export citation: Endnote - Reference Manager
Mail this link - Contents Mailing Lists - RSS
- -