Non-native crayfish upset the natural balance in streams:

Rusty crayfish (via USGS)

Crayfish are an important part of the food web in streams. But in Pennsylvania, an invasive species called rusty crayfish is taking over. And in some areas, they’re so dense they stack on top of each other.

Dave Lieb with the Western Pennsylvania Conservancy says rusty crayfish are bigger and more aggressive, and they’ll eat just about anything, including fish eggs, algae, and insects.

“When you have an exotic crayfish invasion ultimately fish populations tend to decline,” says Lieb.

Rusty crayfish were introduced by people dumping bait or unwanted pets into waterways. So today, it’s against the law in Pennsylvania to move crayfish from one body of water to another.

Get Schooled:

• Learn more about the rusty crayfish from Minnesota Sea Grant.
• Read up on native and invasive crayfish from Michigan Lake & Stream Associations.

Hear More:

Hear Dave Lieb describe the challenges to removing invasive crayfish populations:

The fine print:

• This segment was produced in partnership with Cornell’s Atkinson Center for a Sustainable Future and made possible by the Foundation for Pennsylvania Watersheds.