The ecosystem approach for fisheries advocates an integrated management of marine resources that promotes both conservation and sustainable use in an equitable way. Co-viability is proposed here as a relevant modelling framework to deal with the analysis and exploration of scenarios in line with such an ecosystem approach. Co-viability analysis does not strive to determine optimal or steady-state paths for the joint dynamics of resources and exploitation, but rather aims at maintaining the trajectories of systems within satisfying normative bounds that mix ecological and social requirements. Hence the approach offers a multicriteria perspective and provides ways to analyse the vulnerability of social-ecological system dynamics. Conceptual links to Population Viability Analysis and conservation biology are strong. Moreover it is closely related to the Maximin or Rawlsian approach, which provides important insights regarding intergenerational equity. Examples inspired from the Bay of Biscay fisheries illustrate the proposed approach.