The following excerpt is a summary document provided by Deuchler Environmental (DEI) fish biologist Leonard Dane, originally hosted by the Lake County Health Department (LCHD), co-sponsored by the Illinois Lakes Management Association (ILMA) on April 13th, 2018. The original presentation slides are provided in the Media area of the Blog. All materials are the rights of DEI and should not be reproduced without permission.
Lakes Forum: Carp Removal and Fish Habitat Summary
Common Carp are an exotic, nuisance species that is present in many of Illinois Lakes. The most productive and economical way for the removal of Common Carp is by electrofishing. This method is species selective and can cover the entire area of the lake. It is best to do the removal during the spawning season or during a lake draw down when the fish are congregated in the shallows. Removal of Common Carp using electrofishing will be required over multiple years. In a removal project that has been conducted since 2015, there has been over 5400 pounds of Common Carp removed over three years. Each year there has been a decrease in the catch per unit effort which indicates a decrease in Common Carp in the lake. Once the Common Carp abundance is at a manageable level, you should develop habitat for the desirable fish species in your lake.
This leads us into the importance and types of fish habitat. Fish habitat is the waters and substrate necessary for fish spawning, feeding, and growth. This includes all physical and chemical factors necessary for all life stages. Fish habitat is required to provide an area of protection for small fish, an area for predator to hide to ambush prey, and area for food organisms to colonize and grow. Fish habitat is being eliminated by development within the watershed, increased run-off, management of aquatic plants, removing of woody habitat, shoreline development, and sedimentation.
There are various types of natural fish habitat. These include undercut banks, rootwads, boulders, course woody habitat (logs and trees), aquatic plants, deep water areas, overhanging vegetation, as well as shallow areas. However, often times there is a need to increase the amount of habitat available for the fish. The common artificial fish habitat include fish cribs, Christmas trees, fallen trees, and plastic structures. Fish cribs can be made of various materials and can last over 20 years. They are generally 5-6 feet tall and should be placed in 10-15 feet of water. Christmas trees are easily collected during the months of December and January. They can be weighted on the bottom by placing them in a bucket and adding concrete. These too should be placed in 10 -15 feet of water. Tree falls and fish sticks are full size trees put in the littoral zone and should be placed in areas where they won’t be a navigational hazard. There are many configurations for the use of plastic for fish habitat. For more information on the artificial fish habitat structures please contact me. In general, all the habitat should be placed in deep enough water to be fully submerged at all times. Also, if it is placed in an area where boating will occur, be sure it is deep enough to not become a navigational hazard. It is also important to have the structures weighted and/or secured so they remain in place over the life of the structure.