Pahrump Poolfish antipredator behavior

Predator naïveté has been invoked to explain the impacts of non-native predators on isolated populations that evolved with limited predation. Such impacts have been repeatedly observed for the endangered Pahrump Poolfish, Empetrichthys latos, a desert species that evolved in isolation since the end of the Pleistocene. We tested poolfish for anti-predator responses to conspecific chemical alarm cues released from damaged epithelial tissue versus responses to distilled water as a control. Poolfish did not respond to conspecific alarm cues in terms of two well-documented components of behavioural alarm reactions: reduction in fish activity and movement out of the water column. Epidermal club cells are the presumptive source of alarm cues. We found a low density of club cells in Pahrump Poolfish relative to the well-studied Fathead Minnow, Pimephales promelas, used here as a positive control. Therefore, anti-predator competence mediated by conspecific alarm cues does not seem to be a comp...