Predator‐Naïve Brown Trout ( Salmo trutta ) Show Antipredator Behaviours to Scent from an Introduced Piscivorous Mammalian Predator Fed Conspecifics

Introduced mammalian predators may pose a high risk for native and naïve prey populations, but little is known about how native fish species may recognize and respond to scents from introduced mammalian predators. We investigated the role of diet‐released chemical cues in facilitating predator recognition, hypothesizing that native brown trout ( Salmo trutta ) would exhibit antipredator behaviours to faeces scents from the introduced American mink ( Neovision vison ) fed conspecifics, but not to non‐trout diets. In treatments‐control and replicate stream tank experiments, brown trout showed significant antipredator responses to faeces scent from mink fed conspecifics, but not to faeces scent from mink fed a non‐trout diet (chicken), or the non‐predator food control, Eurasian beaver ( Castor fiber ). We conclude that native and naïve brown trout show relevant antipredator behaviours to an introduced mammalian predator, presumably based on diet‐released conspecific alarm cues and thereby estimate the predation risk.