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Fisheries Behavioral Ecology - Abstracts

Ryer, C.H. and B.L. Olla. 1996. Social behavior of juvenile chum salmon, Oncorhynchus keta, under risk of predation: the influence of food distribution. Environmental Biology of Fishes 45:75-83.


Social interactions can influence both foraging reward and vulnerability to predators. We examined social interactions in groups of juvenile chum salmon, Oncorhynchus keta, receiving food that was either spatially dispersed, with many food items appearing synchronously, or spatially clumped, with individual food items appearing asynchronously. These experiments were conducted both in the presence and absence of predators. When food was dispersed and predators were absent, juvenile chum formed schools and all individuals had access to food, despite frequent agonistic interactions. When predators were present, schooling and feeding continued, but agonistic interactions ceased. In contrast, when food was clumped, dominant fish utilized aggression to monopolize food regardless of whether predators were present or absent, resulting in decreased group cohesion. These results illustrate that food distribution and social interaction may play a role in determining how fish balance predation risk against foraging reward.


Last updated 31 March, 2009

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