Based on published documents and consultation of experts when necessary, the review will: Synthesise the latest understandings of the role of forage fish in ecosystems around the world; Synthesise the principles of management drawn from published studies including the reports produced by the Lenfest, FACTS, and European Union Working Groups; Describe management practices and tools for forage [...] The following sections review the roles of forage fish in the ecosystem starting with the concept of wasp-waist ecosystems, describing the particular role of small pelagic fish (e.g. [...] For instance, the capelin collapse in the Barents Sea led to the abandonment of seabird colonies and the invasion of coastal areas by harp seals in search of food (Gjøsaeter et al. [...] For instance, the removal of large predators that results in the increase of the middle-level prey, which in turn results in the decrease in biomass of plankton species (low trophic level). [...] In the North Sea, the condition of cod and of several large fish predators is linked to the amount of sandeel in their diet (ICES 2010b).