Marbled crayfish (Procambarus virginalis) was created in the pet trade business so there are no natural wild populations. Marbled crayfish have not been detected in Michigan, but they are an important watchlist species. They live in rivers, ponds, wetlands, streams, and can survive drought periods by burrowing underground. These crayfish are typically 4 to 5 inches long, have a marbled pattern on their back that is either olive/dark brown or reddish blue, and have narrow claws.
Have you seen this species? Promptly report it to us or the DNR Fisheries Division. It is important to note the exact location, time, and include photos.
Environmental effects
A single marbled crayfish can establish an entire population. All individuals are female and lay upwards of 700 eggs in the lifetime. The eggs do not have to be fertilized and are identical clones of the adult. Michigan State University extension has a great article that discusses the risk of this species establishment. Marbled crayfish have the ability to deplete food sources for native species due to their reproduction method. They eat algae, fish, amphibians, and aquatic plants. The burrows created in streambanks can cause stabilization issues as well.
Native Look-A-Likes
Michigan’s native calico crayfish (Faxonius immunis) looks similar to the marbled crayfish. Although, typically it does not grow larger than 3.5 inches and is a green/gray color with orange claws. The file below is a great resource for other crayfish native to Michigan.
Prevention is key
The most effective treatment is prevention. Never release non-native species into our waterways. RIPPLE has a great video explaining the importance of proper transfer of non-native species.