Predator detection and learning ability in an endemic lake sucker

Authors: Stephanie Kraft, Todd A. Crowl

Year: 2008 (xl)

Abstract

In 2007, the International Union for the Conservation of Nature (IUCN) reported that 39% of all fish species evaluated are threatened; the highest for any vertebrate group. Threats to fish populations include habitat destruction, alteration, pollution, overexploitation, and nonnative species. Nonnative fish can impact native fish fauna in many ways including competition, disease, hybridization, and predation. Predation is often cited as the largest effect of nonnative fish, possibly due to the inability of native fish to recognize the predation threat posed by nonnatives. Endemic fish may be particularly susceptible to the effects of nonnative predators due to their limited range and often limited evolutionary ties to predators. Many fish assess predation risk through chemical alarm cues, which are stored in skin cells and released when cells are ruptured. The alarm cue serves as a signal of immediate threat to conspecifics in the area. Many fish also possess the ability to detect this alarm cue in the odor of predators who have recently consumed conspecifics. This ability may allow native fish to learn to recognize the odor of nonnative predators and thus evade predation. We investigated this using the June sucker, Chasmistes liorus , an endemic lake sucker in Utah Lake, Utah. Of the thirteen fish species native to Utah Lake only the June and Utah sucker, Catostomus ardens, still reside in the lake. Several nonnative predatory fish, including Largemouth Bass, Micropterus salmoides, have been introduced. We found that while the June sucker did not innately recognize the odor of largemouth bass, they were able to detect chemical alarm cues in the odor of a bass fed June sucker. We also found that June sucker could learn to associate Largemouth Bass odor with predation threat, though this association was short lived.