This aggressive, non-native and invasive species was first discovered in the Monocacy River in June 2007 and later found in Maryland’s portion of the Susquehanna River watershed. Native to parts of Illinois, Indiana, Kentucky, Ohio and Tennessee, it has invaded 14 other states and Canada where it has devastated local aquatic ecosystems. They are known to feed upon fish eggs and can reduce the quality of habitat available to many other species, including native crayfish and game fish.

Rusty crayfish typically have rust-colored spots on either side of the body just in front of the abdomen. Its claws tend to be larger and smoother with fewer wart-like bumps than species native to Maryland such as the devil crayfish. These claws are grayish-green to reddish-brown and have bands on the tips. The rusty crayfish is found in lakes, ponds and streams and can inhabit shallow riffles or pools.

The Maryland Department of Natural Resources is working to control this invasive species, which may have been unintentionally introduced to the state by anglers using it as bait. Anglers are reminded that rusty crayfish cannot legally be imported, sold, possessed live, or released into Maryland’s waters. Anyone finding the species is asked to freeze it, note the exact location and call the Maryland DNR invasive species hotline at 1-877-620-8DNR.

Photograph courtesy of Matt Sell