Red Swamp Crayfish (Procambarus clarkii)

Description

Appearance

Red swamp crayfish are crustaceans with long antennae, two pincer claws, and eight legs. They can grow up to five inches long. The body is dark red, the underside of the tail has a thick black stripe, and the claws and sides have raised red spots. The tip of the head is wedge-shaped, and the seams on the back touch in the center, near the head. Red swamp crayfish create small chimney-like borrows in shoreland areas. Young, small crayfish can be difficult for non-specialists to identify.

Biology

The red swamp crayfish is an omnivore, consuming many food sources such as plants, animals, organic material, sediment, etc. They live in a variety of wet habitats and are tolerant of many environmental conditions. They move across land to find suitable habitat. In shoreland areas, just above the water line, they create burrows with holes up to two inches in diameter and a “chimney” of mud around the opening. Breeding typically occurs in the fall, and females can produce up to 500 eggs, which incubate and mature while attached to the female. Females can be found incubating eggs or carrying young year-round. Recently hatched crayfish remain in the burrow with their mother up to eight weeks. Their life span is two to five years.

Origin and Spread

The red swamp crayfish is native to the southern Mississippi River drainage and inland areas around the Gulf Coast. The species is commonly imported and sold for human consumption, and to schools by biological supply houses, leading to the potential for illegal release into the wild. It is illegal to import red swamp crayfish into Minnesota, dead or alive, without a permit. There is only one confirmed infestation in Minnesota, found in 2016 in Lake Tilde (Clay County), where only two live specimens have been collected. Refer to the infested waters list for current distribution.

Don't be fooled by these look-alikes

Look-alikes:

  • Rusty crayfish (invasive)
  • Northern clearwater crayfish (native)
  • Calico crayfish (native)
  • Virile crayfish (native)

 

Regulatory Classification

Red Swamp Crayfish (Procambarus clarkii) is a prohibited invasive species, which means it is unlawful (a misdemeanor) to possess, import, purchase, transport, or introduce this species except under a permit for disposal, control, research, or education.

 

Threat to Minnesota Waters

Invasive species cause recreational, economic, and ecological damage—changing how residents and visitors use and enjoy Minnesota waters.

Red swamp crayfish impacts:

  • Outcompete native crayfishes for shelter and food.
  • Compete with fishes directly for prey and indirectly by consumption of fish eggs.
  • Disturb shoreland areas through the construction of burrows.

 

What you should do

People spread red swamp crayfish primarily by illegal release: of aquarium pets, of biological specimens, after improper use and disposal of live bait, and after use in live crayfish boils. It is illegal to release or dispose of unwanted aquatic plants or animals in or near public waters. Refer to Habitattitude for alternatives to release.

Whether or not a lake is listed as infested, Minnesota law requires water recreationists to:

  • Clean watercraft of all aquatic plants and prohibited invasive species.
  • Drain all water by removing drain plugs and keeping them out during transport.
  • Dispose of unwanted bait in the trash.
  • Dry docks, lifts, swim rafts and other equipment for at least 21 days before placing equipment into another water body.

Report new occurrences of red swamp crayfish to the DNR immediately by contacting your DNR Invasive Species Specialist or log in and submit a report through EDDMapS Midwest.

 

Control Methods

There is no known population control for red swamp crayfish in natural water bodies at this time. Trapping may reduce numbers, but is not likely to have a significant impact on populations.

 

Resources