In contrast to research on farming systems, research on natural resource systems seldom applies rigorous priority setting techniques, mainly due to difficulties associated with estimating research impact ex ante for such systems. This article presents a replicable approach to priority setting that addresses these difficulties. Assessment is based on multiple criteria, combining economic surplus analysis with subjective scoring, based on information drawn from a cross-country survey of expert opinion. The approach is applied to the WorldFish Center, a global agricultural research organization focusing on living aquatic resources, both farmed and wild. The exercise demonstrates the relevance of conventional evaluation techniques to fisheries research based on a practical application of its impact pathways.