Don’t Let It Loose! - Louisiana red swamp crayfish

Don’t Let It Loose! - Louisiana red swamp crayfish, Procambarus clarkia

Where does the species originate from?

Louisiana red swamp crayfish are native to the Gulf Coast and Mississippi River basin.

How are they introduced and spread?

This species of crayfish make up the vast majority of crayfish consumed as food worldwide. They are commonly sold as pets or as scientific specimen for use in classrooms for educational purposes. Sometimes they are used as live bait. Any of these uses can act as pathways of introduction if people accidentally or intentionally release them into the wild.

Environmental impact:

They feed on aquatic plants, snails, insects and fish and amphibian eggs and young, thus competing with native crayfish that eat the same food types. Red swamp crayfish are highly aggressive and outcompete native crayfish for refuge sites, thus leaving native crayfish exposed to increased predation threats. They are found to reduce amphibian populations in California through direct predation as well as competition for habitat. Invasive populations have also led to declines in native crayfish species in Europe through competition and because they often carry a detrimental crayfish fungus.

Crayfish facts:

·       Red swamp crayfish are immune to newt skin toxins, but native signal crayfish are not.

·       Crayfish usually eat their old exoskeleton (after molting) to recover the minerals contained in  it.

·       Crayfish can live 20 to 30 years.

Don’t Let It Loose!  Releasing classroom pets into the wild is bad for the pet and bad for the environment. Instead of releasing red swamp crayfish into the wild after classroom lessons are complete, some students have enjoyed celebrating the beginning of summer break with a crayfish boil. These crayfish, although a threat to native ecosystems where they invade, are not a threat to your belly. Bon appétit!

Submitted by Briita Orwick, Aquatic Invasive Species Intern - USFWS Pacific Region