Tiny crustaceans invade area waterways

A small crayfish is found along the banks of the Potomac River in Shepherdstown, West Virginia. The thousands of rivers and streams that flow to the Chesapeake Bay are home to many species of native crayfish—also called crawfish, crawdads or mudbugs—which are freshwater crustaceans that resemble small lobsters. But several species of invasive crayfish also call the waterways home, displacing native species of crayfish and reducing the amount and diversity of underwater plants.

Certain species of crayfish are commonly eaten or even kept as pets in freshwater aquariums. But the widespread use of live crayfish by fishermen as bait has led to their introduction in waterways across the region. Unused buckets of live crayfish are often unknowingly dumped into rivers and streams, where they aggressively establish themselves at the expense of native crayfish populations.

Some of the most infamous invasive crayfish in the region include the rusty crayfish (Orconectes rusticus), the red swamp crawfish (Procambarus clarkii) and the virile crayfish (Orconectes virilis). According to the Maryland Department of Natural Resources (DNR), virile crayfish populations in the state are nine times more abundant than all native crayfish species combined. And because removing invasive crayfish would harm other, native species, prevention is the only effective way to stop the spread. The DNR recommends never moving caught crayfish from one waterbody to another and either disposing of unused bait humanely or saving it for future use.

Learn more about invasive species in the Chesapeake Bay watershed.