Chemosensory assessment of predation risk by slimy sculpins (Cottus cognatus): Responses to alarm, disturbance, and predator cues

Slimy sculpins (Cottus cognatus) are small benthic fish that commonly co-oc cur with predatory fishes throughout most of their range in North America. In two laboratory experiments we examined the nature and extent of response s of slimy sculpins to chemosensory cues from predatory brook trout (Salvel inus fontinalis) and chemical alarm cues released by conspecific sculpins. Sculpins responded to three different classes of chemical stimuli: (1) cues of predatory brook trout, (2) damage-released alarm cues from conspecific sculpins, and (3) disturbance cues from conspecific sculpins. Sculpins did not distinguish between trout fed different diets; however, the presence of damage-released alarm cues did enhance the intensity of response to the pr edator chemicals. A histological analysis of the skin of sculpins revealed the presence of large sacciform cells that may act as the source of chemica l alarm signals.