Two Superior, WI, teenagers have discovered
a thriving population of round gobies
(Neogobius melanostomus), an exotic fish, in the Duluth-Superior
harbor near Barker's Island Marina.
"Unfortunately, this is the most significant confirmed report of a goby
infestation in the Duluth-Superior harbor to date," said Doug Jensen, Exotic
Species Information Center coordinator for the University of Minnesota Sea Grant
program. "This also shows that anglers, especially youth, are getting the
message about exotic species. One of the teenagers said he remembered how to
identify the round goby based on television news coverage and a recent newspaper
article," said Jensen.
Cousins Tom and Cody Krause (15 and 13 years, respectively) reported their
finding to Minnesota Sea Grant on Thursday, July 23, after reading a July 20
Duluth News-Tribune article. The article described how scientists found nine
gobies in the harbor during June, and included contact information.
As avid anglers, the Krauses often fish together for yellow perch. They caught
83 round gobies during the week of July 20, east of the Tourist Information
Center along the railroad grade that parallels Highway 2. They gave a sample to
Sea Grant for confirmation.
"Anglers are often the first to find new infestations," said Jensen. "We are
concerned because this new infestation increases the potential for accidental
spread by anglers to other waters.
"The other big news is that gobies now infest all of the Great Lakes," said
Jensen. "Lake Ontario was the lone hold-out until this month. Infestations in
the first two North American inland lakes were also found this summer."
Gobies are considered undesirable because they compete with native fishes for
habitat, disrupt the aquatic ecosystem, and are a nuisance to anglers. The
goby is an aggressive, small, bottom-dwelling fish that is mostly slate-gray,
with frog-like raised eyes, a prominent black spot on the dorsal (top) fin, and
a distinctive, fused, scallop-shaped pelvic (bottom) fin. Identification cards
are available in most Sea Grant and natural resource agency offices around the
Round gobies were first discovered in North America in 1990 in the St. Clair
River near Detroit. They were introduced through ballast water discharged by
transoceanic ships coming from the gobies' native waters in the Caspian Sea and
Black Sea in the Baltic region of Eurasia. Round gobies were first found in
Lake Superior in the summer of 1995.
"To minimize their spread, possession of live round gobies by anglers is illegal
in most of the Great Lakes states and Ontario," said Jay Rendall, Exotic Species
Program coordinator for the Minnesota Department of Natural Resources. "In
Minnesota, it is illegal to possess or transport round gobies. However, it is
legal to possess a frozen goby with the intent to transport it to a local office
for positive identification."
The Krauses caught the gobies using a small, green, ant-style jig, tipped with a
piece of angleworm. Water depth at the site ranges from 2 to 4 feet. The
bottom is covered with gravel and cobble. "Along with breakwalls and riprap,
this is perfect round goby habitat," said Jensen. The gobies came from a
reproducing population--there were mature males, females, and young gobies.
Anyone who catches a round goby in Lake Superior or any inland lake should not
throw it back alive. They should kill the fish by freezing and contact
Minnesota Sea Grant at (218) 726-8712, the fisheries office of a local natural
resource agency, or a U.S. Fish and Wildlife Service office.
Contact Minnesota Sea Grant at 218.726.6191, or by e-mail at email@example.com.