Utilisation de la technique vidéo STAVIRO pour l’observation et le suivi des ressources et des écosystèmes récifo-lagonaires de Mayotte. Etude pilote et recommandations pour les suivis futurs

• In order to assess the sustainability of fish resources in the Natural Marine Park of Mayotte (Western Indian Ocean), indicators and monitoring protocols must be determined. • This study relied on the underwater video technique STAVIRO for assessing fish communities and resources. A pilot survey was conducted in Nov. 2014 in the south-east quarter of the Mayotte lagoon, an area encompassing the marine reserves of Longogori, M’Bouzi and the Saziley Marine Park. Out of 115 stations collected, 104 were analysed for habitat and fish, based on a list of 527 species with fishing, ecological, or emblematic interest (cf. AMBIO/A/1). • 43 indicators were computed, analysed, and for some mapped. The PAMPA computing tool was used in this purpose. • 130 fish species and one turtle species were observed. Surgeonfish and butterflyfish were seen on more than 85% of stations, parrotfish on 80%. Lethrinids, serranids and triggerfish were seen on 60% of stations. • Four habitats were present in the stations: Living coral, slab, detritic hard bottoms and sandy bottoms. Slab corresponded to reef flat, while sandy bottoms were found on the inner slope. Fish were significantly more abundant on the barrier reef and in the living coral habitat. • Seven indicators significantly varied according to fishing pressure. Results showed that it is necessary to redefine fishing pressure estimates, and that pressures per fishing gear would be useful for the assessment. • Commercial species, carnivores, piscivores, herbivores, parrotfish, surgeonfish and serranids were significantly more abundant in the Longogori Marine Reserve than outside of the reserve on the barrier reef. These results were consistent with previous studies. • A two-step monitoring protocol was recommended: a) a survey covering the entire lagoon every 6 year; and b) an annual survey focusing on selected fishing grounds and a reference protected site.