Why are the carp such a big threat to the Great Lakes?
The Big Head and Silver carp are plankton feeders – plankton I all they eat. Plankton is also the main food for most native small fish in the Great Lakes. This includes bait fish (shiner minnows, alewife, and smelt) plus young fish (salmon, lake trout, steelhead, brown trout, perch, bass, and walleye). Plankton is the low end of the food chain. The carp eat 40-60% of their body weight in plankton per day. The average Asian Carp weighs 20+ pounds which means 10# per day of plankton. Once this low end of the food chain is removed/reduced the small fish will not survive and then the larger fish will also have lost their food source and die out. In the Illinois River the Asian Carp now comprise 90% or more of the total biomass of the river. This includes all life in the river. The other species of fish have been displaced and are mostly gone. If the carp get into the Great Lake’s watershed it is expected that the same thing will happen.
