Daniel Kelly | Fondriest Environmental
The rusty crayfish is a freshwater crustacean native to parts of Ohio, Kentucky and Indiana. It chiefly made its home in the Ohio River basin before expanding to other areas within the Great Lakes region. It now inhabits large portions of Illinois, Minnesota, Pennsylvania and Wisconsin, as well as the New England and western states and the Canadian province of Ontario.
Though it is hard to distinguish the rusty crayfish from other freshwater lobsters, there are a few characterizing markings that help:
- Large, grayish-green or reddish-brown claws;
- brown, rust-colored bodies;
- and dark spots on its sides.
The rusty crayfish molts, or sheds its shell, to grow to a maximum length of about four inches. At maturity, males outpace females in size, but both are known to have larger claws than other types of crayfish.
As an invasive species, the rusty crayfish is known to hurt native aquatic plants, small invertebrates and fish. It sometimes uses its pincers to snap at the feet of swimmers, but populations of lake trout, walleye, bluegill and bass seem particularly prone to attacks from rusty crayfish.
Prevent Its Spread
The expansion of rusty crayfish to its non-native areas has been fostered by anglers who use the creature as live bait. The crayfish has been the subject of science class projects in grade schools, and also inhabit home aquaria. Many believe teachers and others have mistakenly released them after use. These and other activities have contributed to its distribution across the United States:
To combat the spread of rusty crayfish, management plans are often implemented on localized levels. They include public education on identifying the crayfish, how to properly dispose of it and other organisms used as live bait, and also emphasize the importance of reporting crayfish sightings to environmental agencies.
In the Great Lakes region, the use of large, predatory fish to control crayfish populations has been suggested. Many states in the area, as well as nearby parts of Canada, have prohibited the possession and transport of rusty crayfish, as well as its use as live bait.