Response of Three Crayfish Congeners (Orconectes spp.) to Odors of Fish Carrion and Live Predatory Fish

Abstract

-We tested the role of olfaction in response to predators and food by three freshwater crayfishes and the potential importance of olfaction in a species invasion. The crayfish Orconectes rusticus (Girard) is replacing Orconectes virilis (Hagen) and Orconectes propinquus (Girard) in northern Wisconsin lakes. To test whether 0. rusticus differs from congeners in its response to the odors of food and predators, we conducted two laboratory experiments comparing five behavioral responses of these Orconectes spp. to odors of dead fish and to live largemouth bass. As expected, all three species responded to carrion odor, suggesting that olfaction is a part of foraging strategy for all three congeners. Orconectes rusticus, however, responded significantly for all five behavioral responses, whereas 0. propinquus and 0. virilis responded significantly for only two and three, respectively. Only 0. rusticus responded to fish predator odor, but in a way contrary to our expectation. In the presence of fish predator odor, 0. rusticus increased time spent out of the shelter. The larger number of significant responses by 0. rusticus suggests that 0. rusticus responded more strongly to the odors of fish carrion and live predaceous fish (as food) than 0. virilis and 0. propinquus. Thus, differential olfaction could contribute to the invasion success of 0. rusticus.