Feeding and aggressive behaviours in juvenile coho salmon (Oncorhynchus kisutch) under chemically-mediated risk of predation

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 coho-conditioned 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 trade-off between juvenile growth and mortality.

The scent of death: Chemosensory assessment of predation risk by prey animals

“…Coho salmon juveniles decrease their activity when exposed to odours of visually hunting common mergansers (Mergus merganser) (Martel & Dill, 1993) and starry gobies (Asterropteryx semipunctatus) move less when they detect chemical cues from the highly visual lizardfish (Synodus variegatus) (Smith, 1989). Tadpoles of the tailed frog (Ascaphus truei) are significantly less active when exposed to water conditioned with cues from predatory Pacific giant salamanders (Dicamptodon ensatus) and introduced brook Downloaded by [University of Nebraska, Lincoln] at 11:38 10 June 2016 trout (Salvelinus fontinalis) than in control treatments (Feminella & Hawkins, 1992).…”

Metabolic fright responses of different-sized largemouth bass (Micropterus salmoides) to two avian predators show variations in nonlethal energetic costs

“…Nonlethal predator effects on fish include altered or restricted habitat use (e.g., Power 1984;Reinhardt and Healey 1997;Allouche and Gaudin 2001); changes in foraging (e.g., Miliniski and Heller 1978;Martel and Dill 1993), territorial (Martel and Dill 1993;Martel 1996), and respiratory (Kramer et al 1983;Smith and Kramer 1986) behavior; decreased growth rate (Power 1984;Diehl and Eklöv 1995); and lower reproductive output (Fraser and Gilliam 1992). As the above studies demonstrate, part of the predator-induced decrease in growth rate and reproductive output is the result of lost foraging opportunities and decreased energy intake.…”

Sexual asymmetry in competitive ability in the immature ayuPlecoglossus altivelis

“…The benefits of increased body size are countered by opposing forces such as survivorship for both sexes. For example, foraging incurs predation risk (Martel & Dill 1993), and physical contest for food implies injury risk (Blanckenhorn 1992). Where cost-benefit relationship for large body size differs between the sexes, sex-specific behavior correlated with growth should evolve even in the immature stage.…”