Prey naivety in the behavioural responses of juvenile Chinook salmon (Oncorhynchus tshawytscha) to an invasive predator

Abstract

Summary 1. Non‐native predators might inflict proportionally higher mortality on prey that have no previous experience of them, compared to species that have coexisted with the predator for some time. 2. We tested whether juvenile Chinook salmon (Oncorhynchus tshawytscha) were less able to recognise a non‐native than a native predator, by investigating behavioural responses to the chemical cues of the invasive smallmouth bass (Micropterus dolomieu) and the native northern pikeminnow (Ptychocheilus oregonensis) in both laboratory and field experiments. 3. Laboratory results demonstrated strong innate antipredator responses of individual juvenile Chinook salmon to northern pikeminnow; fish spent 70% of time motionless and exhibited 100% greater panic response than in controls. By contrast, antipredator responses to the chemical cues of smallmouth bass did not differ from controls. 4. These results were supported by similar differences in recognition of these predator odours by groups of juvenile Chinook salmon in fully natural conditions, though responses reflected a greater range of antipredator behaviours by individuals. In field trials, responses to northern pikeminnow odour resulted in increased flight or absence, reductions in swimming and foraging, and increased time spent near the substratum, compared to smallmouth bass odour. 5. Given that survival of juvenile fish is facilitated by predator recognition, our results support the hypothesis that naivety may be an important factor determining the effect of non‐native predators on prey populations. Efforts to manage the effect of native and non‐native predators may benefit by considering complex behavioural interactions, such as these at the individual and group levels.

Direct and indirect effects of an invasive omnivore crayfish on leaf litter decomposition

“…This naivety behavior against invasive predators was already described for many other organisms (e.g. Edgell & Neufeld, 2008;Kuehne & Olden, 2012).…”

“…A naivety effect has been found in native prey in response to introduced predators, with great declines in density and biomass being reported in distinct organisms (e.g. fishes: McLean et al, 2007;Kuehne & Olden, 2012;invertebrates: Freeman & Byers, 2006;Edgell & Neufeld, 2008). Finally, crayfish may also compete with invertebrates for direct consumption of plant litter due to its omnivore behavior and also compete with other predators for invertebrate prey (Gherardi, 2006).…”

Predation on Fishes in the Sacramento-San Joaquin Delta: Current Knowledge and Future Directions

“…All else being equal, foraging theory predicts that predators will choose prey that maximize their net energy gain (Grossman 2014), although this can be achieved through a variety of methods. It is likely that Delta predators prefer fish prey that are energy-rich (Hartman and Brandt 1995), easily handled and consumed (i.e., small, softrayed and fusiform) and naïve to invasive predators (Kuehne and Olden 2012;Carthey and Banks 2014). Several authors document the importance of behavioral naiveté to predation mortality by demonstrating that invasive Lake Trout and Northern Pike feed disproportionately on salmonids despite the apparently higher abundance of native catostomid prey (Johnson and Martinez 2000;Johnson et al 2002;Lepak et al 2012).…”

Largemouth bass use prior experience, but not information from experienced conspecifics, to avoid capture by anglers

“…In nature, however, individuals are constantly bombarded with a host of cues that must be deciphered to formulate an appropriate behavioural response (Bourdeau, Pangle, Reed, & Peacor, ; Stamps & Frankenhuis, ). The ability to generalise cues to avoid novel threats that are similar to familiar threats can therefore enhance survival probability (Sih et al, ), and individuals that fail to avoid a novel threat (Blake, Alberici da Barbiano, Guenther, & Gabor, ; Kuehne & Olden, ) often do so when the novel threat is highly dissimilar from previously experienced threats (Trimmer, Ehlman, & Sih, ).…”