While populations of top marine predator fish like tuna, billfish and sharks plummet, Stanford University researchers have found that anchovies, sardines, and other small fish are at an equal or greater risk of suffering a collapse. Analyzing over 200 scientific assessments of fisheries around the globe, the Stanford team found that populations of small fish were at least as likely as large ones to have collapsed at some point in the last 50 years. A major cause of population crashes in all fisheries is overfishing. Over 25 percent of the world's fisheries consist of small fish, primarily for use in animal feed, fertilizer and nutritional supplements. Small fish compose a vital link in the oceanic food chain, and a plunge in population could precipitate declines in the mammals, birds and other fish who depend on those species for food. Though small fish may have short reproductive cycles and, as a consequence, recover quickly, the species dependent upon them may take much longer - profoundly disrupting ecosystems.