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GFP News - June 26, 2015

GFP Discovers Invasive Rusty Crayfish in South Dakota Waters

PIERRE, S.D. -- A new aquatic invasive species (AIS) has been discovered in South Dakota waters.

A South Dakota Game, Fish and Parks (GFP) conservation officer in the southeastern part of the state encountered an angler who had illegally trapped crayfish for bait from the Missouri River below Gavins Point Dam. Among that illegal bait was what the conservation officer suspected to be rusty crayfish. Additional GFP samples were obtained from the area and experts confirmed the invasive species.

While its’ impacts may not be as immediately drastic as their AIS counterparts such as Asian carp or zebra mussels, rusty crayfish are an extremely aggressive crayfish species. They typically grow much larger than native crayfish species and directly compete with these species for food and suitable habitat.  

“Native crayfish are an important food item for many sport fish, so establishment of rusty crayfish may not only reduce the availability of an important food source, but the larger size of rusty crayfish can make them unsuitable for fish to eat,” said GFP AIS program coordinator, Mike Smith. “Rusty crayfish have also been found to uproot and limit vegetation growth in water bodies they inhabit. Diverse vegetation provides important habitat for many aquatic organisms including fish and aquatic invertebrates.”

Anglers are reminded that live rusty crayfish are illegal to possess and/or transport.  Furthermore, anglers should be aware that no live bait may be harvested in the portion of the Missouri River below Gavins Point Dam. If an angler believes they have found a rusty crayfish in a new water body, they should contact their local GFP office as soon as possible to report the sighting. 

For more information on aquatic invasive species in South Dakota and to learn more about how to help slow their spread visit Images of rusty crayfish can also be found in the media gallery online at


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