This consultation is a contribution to an assessment of the impacts of basin development on fish production in the Lower Mekong Basin (LMB). Fish of different species respond to development activities, in particular hydropower development, in different ways depending upon their migratory behaviour and their ability to adapt to and tolerate new environmental conditions. In order to better assess the impact of hydropower development on fish production in each country and along main Mekong tributaries, it is necessary to assess i) how migratory a given species is (longitudinal/lateral migrations; scale of migration, resilience to environmental change), i.e. what guild it belongs; ii) what contribution this species makes to fish catches basinwide.