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GLIN==> News Release - Major Zebra Mussel Infestation in Duluth Harbor

                                NEWS RELEASE

9/28/00                Contact: Doug Jensen, MN Sea Grant (218) 726-8712 or
                       Gary Montz, MN Dept. of Natural Resources (651) 297-4888

Major Zebra Mussel Infestation in Harbor Impacts Native Mussels, Boaters

Minnesota Department of Natural Resources (DNR) biologists recently confirmed a 
major infestation of zebra mussels in the Duluth-Superior Harbor.  The extent of
the heavy zebra mussel infestation was discovered while biologists were 
conducting the first comprehensive survey for native freshwater mussels in the 
state.  Officials suspect mild winters and warm summers the last three years 
have created ideal conditions for zebra mussels to grow. 

"One-hundred percent of the native mussels I found on the bayside of Park Point 
were heavily infested with zebra mussels," said Dan Kelner, DNR malacologist who
conducted the surveys by SCUBA diving.  "A lot of the native mussels were 
already dead or dying because the zebra mussels make it difficult for them to 
eat and breathe," he said.  "Every hard underwater surface was carpeted with 
zebra mussels."

University of Minnesota Sea Grant staff using an underwater video camera also 
noticed very heavy colonization of zebra mussels in the Duluth Ship Canal last 

"This increase in zebra mussels and discoveries of zebra mussels attached to 
boats means boaters taking their watercraft from the harbor should take extra 
time and care to inspect and remove zebra mussels," said Doug Jensen, Exotic 
Species Information Center Coordinator for Minnesota Sea Grant. 

"Boat owners who moored their watercraft over the summer in Duluth, the lower 
Mississippi, or the St. Croix River are the ones most likely to be transporting 
zebra mussels," said Jensen.  "They should be prepared to clean their boats 
before leaving water accesses."

"So far, we haven't found any zebra mussels in inland waters in Minnesota, and 
we want to keep it that way," said Jay Rendall, DNR Exotic Species Program 
coordinator.   "Our rules and regulations reinforce that it's important to 
prevent the spread of zebra mussels and other prohibited species, but it's the 
cooperative and voluntary action by boaters that is making the real 

In Minnesota, it is unlawful to transport zebra mussels or aquatic plants on a 
public road or to launch a boat with them attached.  Violators are subject to 
misdemeanor or civil penalties from $50 to $1,000.  "Most boaters are doing a 
good job of inspecting and cleaning off their boats," said Rendall.  "But the 
renewed zebra mussel growth emphasizes the need for boaters to be careful."

One of the native mussel species at risk in the St. Louis River estuary is the 
creek heelsplitter (Lasmigona compressa), which is listed as a species of 
special concern in Minnesota.  "Based on the 98 percent loss of Lake Erie's 
native mussels due to zebra mussel infestation, it doesn't bode well for our 
native mussels in the lower part of the estuary," said Jensen.

More than 70 percent of the mussel species once found in North America are now 
extinct, endangered, or declining, said Kelner.  In Minnesota, more than half of
native mussel species are listed as endangered, threatened, or of special 

Zebra mussels arrived in the harbor in 1989, likely the result of ship ballast 
water discharge.  Across the Great Lakes they are clogging water intake pipes 
and eating plankton  needed by young fish.  Some companies have spent up to $2 
million annually to control this exotic mussel.  Zebra mussels attach to hard 
surfaces, such as boat hulls and motors and can also attach to aquatic plants.  
Microscopic larvae can be transported in bait buckets, live wells, and bliges.  
This makes it important for boaters to remove all plants from their boat and 
trailer, scrape or wash any live mussels from the boat, and to empty water from 
livewells and bait buckets before leaving infested waters.

State officials said that citizens can help  by volunteering for the Zebra 
Mussel Watch program.  Volunteers across Minnesota look for zebra mussels on 
boats and docks in the fall and report new findings to the DNR.  To get involved
for next year, contact the DNR at (651) 296-2835, or Sea Grant at (218) 

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