Social organisation, shoal structure and information transfer

Recent work suggests that the social structure of fish shoals is nonrandom with strong tendencies for self-sorting by phenotype in individuals of several species. The frequency of shoal encounters is high in most freshwater species but lower in pelagic fishes where intershoal distances tend to be greater. Detailed knowledge of the encounter rates between shoals and the exchange rates of individuals between shoals during encounters makes it possible to predict the transmission of learned behaviours through a population.