Hatchery-reared rainbow trout (Salmo gairdneri) planted under partially controlled conditions in an observation stream failed to show social density regulation or socially induced dispersal. Aggression frequency was only an imprecise function of density, and density may not have been influenced by aggression at all. Dispersal following planting was extensive, but it apparently resulted from individual differences in response to the habitat. Group behavior (schooling) affected dispersal radically in some instances, when fish in large groups undertook movements they would not have undertaken alone or in small groups.
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Thomas M. Jenkins (1971) studied this question.