Authors: Guy Martel Lawrence M Dill
Publish Date: 1993/06/01
Volume: 32, Issue: 6, Pages: 365-370
Abstract
Juvenile coho salmon Oncorhynchus kisutch spend the first year of their lives in their natal streams where they may often hold feeding territories They also face significant risk of predation by birds and fish and should alter their behaviour to reduce risk of mortality when these predators are present Although there is laboratory evidence that coho react to predator visual stimuli chemoreception of avian predator presence has not previously been reported We tested the influence of chemical stimuli of common merganser Mergus merganser preying on juvenile coho on two aspects of coho territorial behaviour foraging and aggression in flowthrough aquaria After a mixture of merganser and cohoconditioned water was introduced into the system juvenile coho significantly reduced their attack distance on drifting prey The fish also significantly decreased their aggressive behaviour directed towards mirrors total number of acts intensity of acts and time spent when the same odour was present They did not change their behaviour in either experiment after control introductions of water treated with fish alone These results are interpreted within the framework of a tradeoff between juvenile growth and mortality
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