The Kick-off meeting of SOMBEE took place in Montpellier from the 9^th to the 11^th Of October 2019. The Biodiversa and Belmont Forum project will develop over the coming three years, with great scientific challenges to innovate our capacities in projecting the future of marine biodiversity. Ten teams from around the world discussed how to best model the eco-evolutionary dynamics of whole marine ecosystems, identified the data needed to parameterize and calibrate these novel models, elaborated a working plan to engage multiple stakeholders in the co-building of fishing and climate change scenarios that are meaningful at the regional and local scale. SOMBEE partners are thankful to the Advisory board (Mark Dickey-Collas, Paul Leadley, Steve Mackinson, Frédéric Le Manach) whose excellent feedbacks helped to better align with expectations from the academic, conservation, and fisheries management world.