 In most upwelling systems, these species are either anchovies or sardines, and usually only one is present, although two or three species may be present occasionally.These fish are an important food source for predators, such as large pelagic fish, marine mammals, and marine birds.Although they are not at the base of the trophic pyramid, they are the vital species that connect the entire marine ecosystem and keep the productivity of upwelling zones so high

A major threat to both this crucial intermediate trophic level and the entire upwelling trophic ecosystem is the problem of commercial fishing.