Asian Carps Establishment into the Great Lakes: Incorporating Foraging Behaviour and Alternate Food Sources

There is mounting concern regarding the potential for invasion of the Asian Silver Carp (Hypophthalmichthys molitrix) and Bighead Carp (H. nobilis) into the Great Lakes ecosystem given their history of rapid expansion and domination of the Mississippi River system. Asian carps differ from other invading freshwater fishes in that they are an active, large bodied highly opportunistic planktivore that can consume a wide diversity of prey including members of the microbial food web (ciliates and nanoflagellates). Silver carps are considered phytoplanktivorous, consuming plankton down to several microns in size (including cyanobacteria), but also consume a wide range of zooplankton, and while Bighead carps are considered primarily zooplanktivorous, they also consume algal food. Given the threat to the Great Lakes fisheries, Canada and the US have established the Bi-national Asian Carp Risk Assessment Action Plan to determine risks of arrival, survival, establishment, spread and ecological impacts. The range of Asian carps are not likely to be restricted by climatic conditions but rather food resources and spawning habitat. Here I will discuss the current state of knowledge on the food requirements for Asian carps, identification of alternate food sources from each of the Great Lakes and how high-risk regions for establishment and population growth within the Great Lakes have been identified using an individual-based, area-restricted modeling approach driven by food resources.