Title
Progress of the REMMOA aerial surveys conducted in the
French EEZ and adjacent waters: contrasted cetacean
habitats in the southwest Indian Ocean
Author(s)
Laran, S.;Doremus, G.;Mannocci, L.;Van Canneyt, O.;Watremez, P.;Cadinouche, A.;Dulau-Drouot, V.;Mayer, F.M.;Monthy, D.;Andrianarivelo, N.;Razafindrakoto, Y.;Toilibou, A.;Rildoux, V.
Published
2012
Abstract
The French Agency for marine protected areas (Agence des aires marines protégées; AAMP) decided to conduct a series of
surveys from 2008 onwards following a standardized methodology that would allow comparisons within and between regions as
well as temporally, for the identification of hotspots of abundance and diversity and the establishment of a future monitoring
scheme of cetacean and other pelagic megafauna across the French EEZ. The general study areas of the REMMOA surveys
include all sectors of the French EEZ in the tropical Atlantic (French Caribbean and Guiana), southwestern Indian (Reunion
Island, Mayotte and the Scattered Islands) and south Pacific oceans (French Polynesia, New Caledonia, Wallis and Futuna). The
objective of this paper is to present the analysis of the Southwestern Indian Ocean survey with a focus on comparing cetacean and
other pelagic megafauna communities in areas characterized by contrasted oceanographic conditions. The SW Indian Ocean
survey was conducted from December 2009 to April 2010. Total effort deployed in the six areas amounted to 84,000 km. A total
of 1,274 sightings of cetaceans were collected on effort, including 17 different taxa. In addition to this, 8 sightings of the sirenian
Dugong dugon were collected, as well as over 22,343 seabird, 586 turtle and 338 elasmobranch sightings. Relative densities were
estimated for six groups of cetaceans and for seabirds, sea turtles and elasmobranchs. Southern and central Mozambique Channel
was characterized by the dominance of large delphininae, with a maximum density encountered in the central part of the channel
(27.3 x10
-2
ind.km
-2
, CV=23%). Delphininae relative density peaked around the Seychelles Plateau (32.6 x10
-2
ind.km
-2
,
CV=29%). The northern Mozambique Channel was dominated by globicephalinae and was also favorable to beaked whales
(D=0.52 x10
-2
ind.km
-2
, CV=43%). Northeast of Madagascar and around La Reunion and Mauritius Islands densities were very
low in general, except for deep divers. In the near future the priority is to conduct the same kind of analyses on French Polynesia
data and complete the first series of REMMOA surveys in the South West Pacific Ocean between November 2012 and March
2013. The long term objectives of the REMMOA surveys is to establish an initial situation of cetaceans and other pelagic
megafauna diversity and relative abundance and to build up a monitoring strategy to be implemented from this point onwards.
When the series of surveys is completed, it is planned to hold a workshop that would examine the statistical properties of the
complete data set and infer recommendations for monitoring strategies. In this exercise, expertise from the marine mammal,
seabird and fish scientific communities would be most welcome and the outcomes of this work extremely useful for all
stakeholders and managers in charge of monitoring cetaceans across the tropics.
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