Marine tidal energy technology is still in its infancy in France and potential environmental impacts on the seabed are virtually unknown. The first French pilot project is currently launched close to Paimpol and the Bréhat Island (Brittany). Environmental monitoring has started in 2012 to assess the baseline of benthic compartment before deployment and the grid-connections of the 4 turbines. The Paimpol-Bréhat tidal site is located on a hard rocky bottom where conventional benthic survey techniques are unsuitable. This paper describes the methodology used to assess the initial state of benthic communities on the turbines and cable deployment area and presents the first results of the mapping and monitoring of the targeted benthic ecosystem.