Sea lamprey Origin: Atlantic Ocean. Entered via Erie Canal in 1921. Problem: Attaches to and kills marine life, causing financial
difficulties for fisheries and are a threat to native species. Location: Great Lakes; hot zone is St. Mary's River,
which connects Lake Superior and Lake Huron east of Michigan's
Eurasion ruffe Origin: Azov, Black and Caspian seas. Entered Duluth
Harbor via ballast water in 1986. Problem: Bottom dwelling fish that competes with native
fish for food and habitat. Spine on gills and fins make them
difficult for other fish to eat. Location: Great Lakes and the Sand River in northern
Zebra mussel Origin: Caspian Sea. Spread by ballast water to the United
States in the 1980s. Problem: Attaches to hard surfaces and reproduces by
the millions annually. Location: Great Lakes, Mississippi River, St. Croix River
and some inland lakes such as Lake Pepin and Lake Zumbro in
Round goby Origin: Azov, Black and Caspian seas. Entered via ballast
water in 1990. Problem: Bottom dweller that takes over prime native
fish spawning sites. Easily identified by its underside suction
disk that has a clam shell-like appearance, which helped anglers
catch 120 of them in and around Lake Superior in 1998. Location: Great Lakes.
Eurasian watermilfoil Origin: Europe, Asia and North Africa. Believed to have
been intentionally introduced for aquarium use in the 1960s.
Problem: Thick vegetation; degrades water quality, restricts
swimming, fishing and boating; clogs water intakes. Depletes
water oxygen levels for wildlife. Location: In 48 states; abundant in the Great Lakes and
the Twin Cities metro area.
Spiny water flea Origin: Great Britain, Northern Europe, Caspian Sea.
Entered via ballast water in 1984. Problem: Small crustacean competes with small fish for
food and reproduces rapidly. Sharp spine makes it hard for other
fish to swallow. Location: Great Lakes and some inland lakes.