[acn-l] Invasive Crayfish Discovered in St. Louis Bay

Jay DeLong (thirdwind at att.net)
Tue, 13 Jul 1999 19:48:09 -0700

DATE: 7/8/99
CONTACT: Doug Jensen

Invasive Crayfish Discovered in St. Louis Bay

Rusty crayfish (Orconectes rusticus) were found for the first time in the
Duluth-Superior harbor at Minnesota Power's M. L. Hibbard Steam Electric
Station near the Bong Bridge on June 25. While inspecting for zebra
mussels, Doug Jensen, exotic species expert for the University of Minnesota
Sea Grant Program, and Eric Skadsberg, Plant Manager, collected four of
these invasive crayfish from the screens that guard the plant's water intake
pipes. "Rusty crayfish are aggressive, displace native crayfish, and can
clear-cut aquatic plant beds," said Jensen. "They can grow quickly, avoid
fish predation, and are known to chase fish from nests then eat the eggs."

Minnesota Sea Grant staff responded by sampling 80 locations throughout the
harbor and up to the Fond du Lac Dam to gauge the extent of the infestation.
Based on the trapping efforts, rusty crayfish are also present near the
Blatnik Bridge. Three native crayfish species were also caught. During the
crayfish survey, Minnesota Sea Grant staff also caught nine species of fish,
of which three (round goby, ruffe, and threespine stickleback) are invasive

Selling live crayfish for bait or aquarium use is illegal in Minnesota. Live
crayfish taken from a waterbody can only be used as live bait in that same
waterbody, according to Minnesota Department of Natural Resources
regulations. According to Wisconsin Department of Natural Resources
regulations, crayfish may only be used as live bait in the Mississippi River
and the Great Lakes.

Jensen believes we can prevent or slow the spread of rusty crayfish through
education. He urges everyone not to transport or release crayfish. Boaters
should avoid transporting aquatic plants, drain water from boats and motors,
and discard unwanted bait on land. "Once rusty crayfish gain a foothold
there is no environmentally friendly way to eradicate them," said Jensen.
"Preventing the spread of rusty crayfish and all the other aquatic invaders
from the harbor is an essential part of protecting our inland waters."

Rusty crayfish have been found in at least 41 lakes and rivers in Minnesota.
In the Arrowhead region, they have been found in 15 locations in St. Louis
County including: Bass Lake, Birch Lake, Eagles Nest 1, 2, 3, 4, East
Vermilion, Esquagama Lake, Little Long Lake, Rock Pond, Shagawa Lake,
Shagawa River, Spring Lake and Vermilion Lake. They have been reported from
eight locations in Lake County including: Basswood Lake, Fall Lake, Moose
Lake, Newfound Lake, Newton Lake, Skull Lake, Sucker Lake, and Triangle
Lake. In Cook County, they have been found in the Pigeon River and Lake

Rusty crayfish are native to the Ohio River Basin. This pest may have
spread to Minnesota through ballast water discharge, live bait use by
non-resident anglers, and releases by students or teachers after studying
crayfish purchased from a biological supply house.

A fact sheet describing biology and impacts of rusty crayfish is available
from Minnesota Sea Grant. For a free copy of Rusty Crayfish: A Nasty
Invader contact Minnesota Sea Grant at 218/729-6191 or visit our Web site at
www.d.umn.edu/seagr/. For more information contact Doug Jensen, Exotic
Species Information Center Coordinator, at 218/726-8712 or
djensen1 at d.umn.edu.

Minnesota Sea Grant is a federally and state funded program that supports
research and public education programs related to Lake Superior and
Minnesota's inland waters.

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Mark D. Sytsma
Environmental Biology Dept.
Portland State University
Portland OR 97207-0751

Voice: 503-725-3833
Fax: 503-725-3888

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