Is that an invasive crayfish in your fish tank?
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EmailUse the new Great Lakes Almanac to Invasive Crayfish to learn more about pesky crustacean invaders and how to identify them.
What do pet stores and your favorite creek have in common? They are both places you might come across a crayfish. Crayfish are important members of aquatic ecosystems and are a favorite snack for birds and other animals. They are also popular pets. Unfortunately, well-meaning people who keep crayfish in aquariums sometimes release them into waterbodies where they have the potential to become invasive and harmful to our environment. Non-native crayfish such as the red swamp crayfish can rapidly reproduce, outcompeting our native species for food and habitat, and alter aquatic ecosystems. Of the ten crayfish found in Michigan waters, two are invasive: rusty crayfish and red swamp crayfish. Preventing the introduction of non-native crayfish is essential to the health of Michigan waterways.
How do you know if you have an invasive crayfish?
There are a wide variety of crayfish available in the pet industry and retailers, suppliers, and hobbyists are in a unique position to aid in the detection and prevention of invasive species. It is imperative for retailers and hobbyists to know how to identify and report invasive species; however, crayfish identification can be very challenging. With over 600 crayfish species worldwide it can be hard to figure out if a crayfish in a fish tank or available online is a pesky invader. Retail crayfish are especially difficult because they have been bred to have diverse colors, color patterns, and shapes. For this reason, physical features, not color alone, should be used to determine a crayfish species. Research has also shown that crayfish are not always sold at the wholesale or retail level with correct labels, adding another layer of complexity. When scientific names are provided on shipments or tanks, they can be inaccurate due in part to the difficulty of identifying crayfish species. And a variety of simple common names such as red crayfish, white crayfish, striped crayfish can be used to describe the same species.
To aid in the identification of invasive crayfish most likely to appear in the pet trade, Michigan State University collaborated with invasive species specialists across the region to create the Great Lakes Almanac to Invasive Crayfish. This pamphlet, which folds out into a poster, highlights four invaders: rusty crayfish (Faxonius rusticus), red swamp crayfish (Procambarus clarkii), marbled crayfish (Procambarus virginalis), and Australian crayfish (Cherax species). For each crayfish, a detailed description and illustration is provided highlighting significant physical features. This new educational tool, developed with funds from the Great Lakes Restoration Initiative, is being distributed to pet retailers and conservation partners across the Great Lakes region. It is also available to order for free on the Michigan State University Extension Reduce Invasive Pet and Plant Escapes (RIPPLE) website.
The pamphlet also includes recommended steps to take if a suspected invasive crayfish is found. Steps include taking multiple photos from a variety of angles and reporting it to the Michigan Department of Natural Resources. Reporting when invasive crayfish are found, either in retail locations or the wild, is extremely helpful. Reporting these occurrences provides invasive species specialists with valuable information to aid in future educational products. Reports of invasive crayfish in the wild may also result in management action. More identification and reporting information is provided on the Michigan Invasive Species Program website.
Michigan regulations prohibit or restrict four crayfish species: marbled crayfish (Procambarus virginalis), red swamp crayfish (Procambarus clarkii), common yabby (Cherax destructor) and rusty crayfish (Faxonius rusticus). However, regulations differ across the United States which can cause confusion for wholesalers who ship nationwide. In addition, crayfish are extremely agile and commonly hitchhike on aquatic plants and in other fish shipments when they were not intentionally bought.
The Great Lakes Almanac to Invasive Crayfish, along with other invasive species outreach materials, are available to order for free on the Reduce Invasive Pet and Plant Escapes (RIPPLE) website. Since 2015, Michigan State University Extension has been providing free educational materials to Michigan pet retailers and hobbyists about responsible pet ownership and handling of plants and animals to prevent their release into the wild. RIPPLE's education initiatives are coordinated by Michigan State University Extension in partnership with the Michigan Department of Environment, Great Lakes and Energy, Michigan Department of Natural Resources and the Michigan Department of Agriculture and Rural Development. RIPPLE is funded by the Michigan Invasive Species Grant Program.
