Crawfish, also known as crayfish or crawdads, are common freshwater crustaceans found throughout Illinois waterways. Their widespread presence means they are an integral part of the state’s diverse aquatic ecosystems.
Crawfish Species in Illinois
Illinois is home to a variety of native crawfish species. These include the virile crayfish (Faxonius virilis), found across the state in many lakes and ponds, the prairie crayfish (Procambarus gracilis), known for its burrowing habits, the white river crayfish (Procambarus acutus), papershell crayfish (Faxonius immunis), and devil crayfish (Lacunacambarus diogenes).
However, the state’s crawfish populations also include introduced species that challenge native biodiversity. The rusty crayfish (Faxonius rusticus) became prevalent in Illinois during the 1990s and is now found across the state. This aggressive species can outcompete native crawfish for resources and habitat, and it is known to consume aquatic vegetation and fish eggs.
Another invasive species, the red swamp crayfish (Procambarus clarkii), is also present in Illinois, particularly in the Chicago region. This species is highly invasive and can cause significant ecological and structural damage, including destroying nesting grounds and competing with other aquatic species. Importing or possessing live rusty or red swamp crayfish is prohibited in Illinois due to their ecological threat.
Where Crawfish Live
Crawfish in Illinois inhabit a broad spectrum of freshwater environments. They can be found in various aquatic settings, including streams, rivers, lakes, ponds, and even temporary wetlands and ditches. Some species, like the virile crayfish, thrive in the open waters of lakes, even at depths of 60 feet in Lake Michigan.
These crustaceans seek out habitats that offer shelter and food. They often hide under rocks, woody debris, or submerged vegetation, which provide protection from predators. Many crawfish species are also adept burrowers, constructing complex tunnel systems in muddy banks or along the margins of water bodies. These burrows, sometimes marked by distinctive “mud chimneys” at the surface, allow them to access groundwater during dry periods and escape extreme temperatures.
Their Role in Ecosystems
Crawfish are integral to the health and functioning of Illinois’ aquatic ecosystems. They act as omnivores, consuming a variety of organic materials, including decaying plant matter, small invertebrates, and even fish eggs. This feeding behavior contributes to nutrient cycling and the decomposition process, helping to maintain water quality.
Beyond their role as consumers, crawfish serve as a food source for numerous other animals. Fish such as bass, crappie, and panfish rely on crawfish as a significant component of their diet. Various birds, including herons, and mammals like raccoons and river otters also prey on crawfish, demonstrating their position in the food web. Additionally, some crawfish species are considered “ecosystem engineers” because their burrowing activities can influence sediment composition and water flow, creating microhabitats that benefit other aquatic organisms.
Rules for Catching Crawfish
For recreational crawfish harvesting in Illinois, a valid sportfishing license is required for anyone 16 years or older. This license permits the taking of crawfish for personal use, but not for sale or bartering.
Legal methods for capturing crawfish include using hands, dip nets, minnow traps, cast nets, and minnow seines. Specific regulations apply to the equipment used: crawfish traps, for instance, cannot exceed 24 inches in width or diameter, 36 inches in length, or have a mesh larger than 1/2 inch bar measurement. Each entrance aperture on traps must not exceed 1.5 inches in diameter, and unattended traps require a tag displaying the operator’s name, mailing address, and phone number.
Collected live crawfish must be used as bait only on the specific body of water where they were caught and cannot be transported to other water bodies. It is illegal to possess, import, sell, or use live rusty crayfish or red swamp crayfish as bait in Illinois. However, dead specimens of these invasive species can be used as bait. Anglers should always consult the current Illinois Department of Natural Resources (IDNR) regulations for the most up-to-date and site-specific rules before harvesting crawfish.