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Aerial and snorkelling census techniques for estimating green turtle abundance on foraging areas: A pilot study in Mayotte Island (Indian Ocean)

Published online by Cambridge University Press:  15 July 2005

David Roos ,
Dominique Pelletier ,
Stéphane Ciccione ,
Marc Taquet  and
George Hughes
David Roos
Affiliation:
Laboratoire Ressources Halieutiques, Ifremer, BP 60, 97822 Le Port Cedex, France
Dominique Pelletier
Affiliation:
Laboratoire MAERHA, IFREMER, BP 21105, 44311 Nantes Cedex 3, France
Stéphane Ciccione
Affiliation:
Centre d'Étude et de Découverte des Tortues Marines de La Réunion, BP 40, 97898 St-Leu Cedex, France
Marc Taquet
Affiliation:
Laboratoire Ressources Halieutiques, Ifremer, BP 60, 97822 Le Port Cedex, France
George Hughes
Affiliation:
4 Thorngate Road Pietermaritzburg 3201, South Africa
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Abstract

Monitoring the abundance of green turtles (Chelonia mydas) is necessary to assess population trends and risks of collapse. This note presents a study aimed at comparing three techniques for the direct estimation of green turtle numbers in their foraging habitats (seagrass beds and reef flats). The experiment was carried out at Mayotte Island, Western Indian Ocean. The techniques involved were surveys by snorkel, and aerial surveys using a microlight aircraft and a paramotor. Each technique had shortcomings and advantages. While each technique provided estimations of turtle numbers only surveys by snorkel permitted identification of species and sex, whenever visibility and turtle behaviour permitted. Along the shorelines, and over foraging areas, the paramotor was found to be most suitable for direct estimations of turtle numbers. The major advantage of this technique lied in its capability to obtain a synoptic snapshot of turtle distribution over foraging areas. Linear surveys from a microlight aircraft are better suited to monitor foraging areas located further away from the shore.

Keywords

Green turtleChelonia mydasAbundance estimationAerial surveySnorkelling surveyForaging habitats
Type
Research Article
Information
Aquatic Living Resources , Volume 18 , Issue 2 , April 2005 , pp. 193 - 198
Copyright
© EDP Sciences, IFREMER, IRD, 2005

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