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For Release:   IMMEDIATELY
September 3, 1999

Fred Binkowski, Senior Scientist, Great Lakes WATER Institute, 
and UW Sea Grant Advisory Services Aquaculture Specialist, (414) 382-1723

Phil Moy, UW Sea Grant Advisory Services Fisheries Specialist, (920)


MADISON (9/3/99) - Bob Wasikowski Sr. spends the early mornings of his
retirement years fishing in Milwaukee Harbor - and occasionally advancing
scientific knowledge of the lake.
	Last week Wasikowski took several fish to the Great Lakes WATER
Institute in Milwaukee for identification. Fisheries biologist Fred
Binkowski identified the fish as white perch, an aggressive, non-native
predator previously unknown in Wisconsin waters of Lake Michigan outside of
Green Bay.
"I knew it was a white perch," Wasikowski said.  "But my buddies said it was
a white bass.  I'd seen them up near Marinette [on Green Bay] before, and I
knew they weren't white bass.  The only way to settle the matter was to take
them in." 
Phil Moy, Advisory Services fisheries specialist for the University of
Wisconsin Sea Grant Institute, said it was yet another case of the angling
public helping scientists and resource managers keep abreast of the rapidly
changing fish populations in Lake Michigan.
"They're our eyes and ears out there," Moy said.  "They're often the first
to find an invasive species in a new area."
In early July, anglers alerted the Wisconsin Department of Natural Resources
that another invasive predator, the round goby, had moved into Milwaukee
And in late August, sport fishermen - and fisherkids - helped the DNR
document the presence of round gobies in Sturgeon Bay. A WDNR staff member
there was talking casually to a fisherman at an automotive service garage.
The fisherman mentioned he had caught round gobies at Sunset Park. When DNR
divers went to investigate, they met several children fishing from shore.
The children donated a few gobies they had caught to the investigation.
The DNR divers found about 50 gobies of various sizes among the rocks and
riprap near the boat ramp at the park.  Based on the number and size
distribution of the gobies observed by the divers, it seems likely the
population has been established for some time. 
 	Like the Milwaukee Harbor population, this introduction is most
likely a result of inter- or intra-lake transport of the fish in the ballast
water of a freighter, Moy said.  Lake vessels are commonly brought for
repair at the shipbuilding facilities near Sunset Park.
Both gobies and white perch may out-compete more desirable native fish like
yellow perch for food and habitat.  
White perch, which have inhabited Green Bay for several years, are known to
be aggressive invaders and may have contributed to the decimated populations
of yellow perch in Lake Michigan during the nineties, according to
"Finding white perch in Milwaukee Harbor makes them new suspects in the
yellow perch case - suspects with a rap sheet," Binkowski said.  "We know
from Sea Grant-sponsored research in Green Bay that they eat young yellow
perch, both larvae and fingerlings.  White perch are the junkyard dogs of
the fish community." 
Despite their common name, white perch are not related to yellow perch.
White perch are actually members of the same family as white, striped, and
yellow bass, which they more closely resemble. The white perch, an East
Coast native, first found its way into the Great Lakes in the 1980s. In its
native range it is anadromous, spending its adult life in ocean but swimming
up coastal streams to spawn. 
The white perch has a mottled coloration on the sides and back, lacks the
dark colored, horizontal black bars along the body seen on white bass, and
does not get as large.
Other aquatic invasive species also threaten Wisconsin waters, Moy said.
Zebra mussels, ruffe, Eurasian water milfoil, and invasive zooplankton like
the spiny water fleas Bythotrephes cederstromi and Cercopagis pengoi are
present in Wisconsin's Great Lakes waters and have already spread to some
inland waters.  Like gobies and white perch, ruffe prey upon and compete
with native fish for forage and living space. The spiny water fleas displace
native zooplankton, but they have long spines that make it difficult for
small sport fish to consume them.
These species depend on water flow or human activities to spread, Moy said.
They are likely to spread into areas adjacent to their new locations and to
other ports that lake vessels frequent either for freight transportation or
for repair.
Anglers who find organisms that they cannot identify should take one to a
Sea Grant or DNR office.  These animals should not be returned to the water.

Once these organisms are established in Lake Michigan or Lake Superior there
is almost no way to control their spread throughout those lakes, Moy said.
The public can, however, help prevent their spread to inland lakes and
Anglers and boaters should be careful not to transport animals, vegetation,
or water from one body of water to another.  This includes water in bait
buckets, live wells, and bilge water and any vegetation that tangles onto
the trailer as boats are launched or retrieved. Boaters should carefully
inspect their boats for the presence of zebra mussels that attached during
summer use.
Free, wallet-sized cards for identifying gobies, ruffe, and zebra mussels
are available from these UW Sea Grant offices:

		Sea Grant Fisheries Specialist UW-Manitowoc
		705 Viebahn St.  
		Manitowoc, WI 54220-6699
		(920) 683-4697

		Sea Grant Water Quality Specialist
		ES105 UW-Green Bay
		Green Bay, WI 54311-7001
		(920) 465-2795

		Sea Grant Education Specialist
		Great Lakes WATER Institute
		600 E. Greenfield Ave.
		Milwaukee, WI 53204-2944
		(414) 227-3291

		Sea Grant Communications Office
		1975 Willow Dr.
		Madison, WI 53706-1177
		(608) 263-3259

Created in 1966, Sea Grant is a national network of 29 university-based
programs of research, outreach, and education dedicated to the protection
and sustainable use of the United States' coastal, ocean, and Great Lakes
resources.  The National Sea Grant Network is a partnership of participating
coastal states, private industry, and the National Sea Grant College
Program, National Oceanic & Atmospheric Administration, U.S. Department of


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