Abstract
Global mesopelagic stock estimates indicate a potential biomass which goes far beyond any other commercial fishing resources. Since the 1970's, mesopelagic resources around the world have thus been a subject for developing new large-scale fisheries. However, empirical catch rates from several trial fisheries from other countries and in Norway, do not correspond to global biomass estimates, and none of the commercial attempts have proven economically viable. Instead, the rather disappointing results have revealed major knowledge gaps concerning stock assessment, their position in the ecosystem and technological development for commercial harvesting. As the implementation of sustainable management principles are mandatory for commercial fisheries, this article addresses the present status and what managerial knowledge needs are relevant for the development of sustainable mesopelagic fisheries.