Humpback whale lives in Madagascar coastal water during their breeding and calving period. Sainte Marie channel is an important concentration area to C3 population and first place for whale watching activities in the Indian Ocean. Partnership was established since 2009 between Cétamada association, eco volunteer and promoter whale - watching trip hotel. Objectives ar e to manage whale - watching trip, to promote environmental education and to collect scientific data. Data were collected using touristic observations and approaches. Data analysis allows studying structure, distribution and attendance areas of this populati on, an important means of establ ishing a conservation strategy i n this area. This sampling method allows collecting GPS coordinates, number and group types, and individual number observed. Work performed with one Cétamada partner in 2011 and 2012 , using database online (Cetanet .org ) showed th e following: 1606 tourists participated to whale watching trip, which allowed making 559 hours of sampling. In total, 1609 humpback whales were recorded. Distribution and social structure of C3 population are regular in this channel. Observation frequency shows no temporal and spatial variation although population is located in varying depths. This study could be adapted in some areas in Madagascar where touristic activities are associated in humpback whales. This participative method enable to conduct, loc al population, touristic actors and tourist to protect and to conserve marine wildlife. It would help to understand characteristic and to study population modelling in different area.