Press Release Posted 5/22/07
- The Department of Natural Resources announced Saturday that two fish from Little
Lake Butte des Morts in the Lake Winnebago chain of lakes have preliminarily tested
positive for the deadly fish virus called viral hemorrhagic septicemia or (VHS).
Additional dead fish samples taken from Lake Winnebago, itself, appear to have
Though VHS is
not a health threat for people who eat or handle fish infected with the virus,
it can infect more than 25 game fish, panfish and bait fish species. State fish
managers had suspected it to be present in Lake Michigan and possibly in Lake
Superior and in the Mississippi River. This would be the first infection to be
confirmed in Wisconsin inland waters. Wisconsin
recently enacted emergency rules for boaters, anglers and people who harvest wild
bait to prevent the spread of VHS in inland waters
"This is a major fish health crisis," said Fisheries Director Mike Staggs,
"We have to take aggressive steps now and enlist the help of the public to
stop this spread."
Fish managers met Saturday to implement immediate steps to deal with the infection
and limit its spread. DNR asked the Fox Locks Authority to close the Menasha Lock
immediately and to keep it closed until more information about the spread of the
disease could be confirmed; boaters can expect to be turned back from the lock
starting today. In addition, DNR began the process of posting all boat launches
with actions boaters should take to avoid spreading the disease.
"We need to err on every possible side of caution," Staggs said. "Believe
me, nobody wants to see this disease get into more of our lakes. Do not take live
fish (including unused bait minnows) away from the landing or shore. Drain all
water from bilges, bait buckets, live wells, and other containers when leaving
the landing or shore."
Lake Butte des Morts is downstream from Lake Winnebago and separated by one dam
and one functioning lock, which has now been closed. The Lake Winnebago chain
is home to Wisconsin's unique sturgeon population. On May 11, 2007 the University
of Wisconsin Veterinary Diagnostic Lab (WVDL) informed DNR that two samples of
freshwater drum taken from Little Lake Butte des Morts on May 2, 2007 had tested
positive for VHS. The samples have been sent to an approved federal lab for confirmation.
The fish were collected by DNR fisheries staff during muskellunge spawning
netting and were submitted for testing because they had shown external signs of
VHS. Since that time, DNR has been receiving reports of hundreds of freshwater
drum dying on Lake Winnebago, itself. On May 9 and 10 samples of those dead fish
were sent to WVDL for testing. A visual inspection of the Lake Winnebago fish
by DNR's certified fish health inspector showed the same external signs of VHS
as the Little Lake Butte des Morts fish. Also the DNR staff that collected the
fish on Little Lake Butte des Morts reported seeing dead and dying drum washing
over the dam separating that water from Lake Winnebago.
Because the virus can infect so many different ages and species of fish, VHS could
spread more quickly in inland lakes, which are much smaller than the Great Lakes,
potentially devastating fish populations and fishing opportunities. Walleye, spotted
musky, yellow perch, bluegill and northern pike are all susceptible to the virus,
as are common bait species such as emerald and spot-tail shiners.
appealing to anglers, boaters and other water users to help prevent the further
spread of VHS by taking a few simple steps:
· Never move live fish or fish eggs to other waters and always buy bait
minnows only from Wisconsin bait dealers because bait from other states may not
have been tested for VHS. These steps are required by the new emergency rules.
· Inspect boat, trailer
and equipment and remove visible aquatic plants, animals, and mud before leaving
the lake launch.
water from boat, motor, bilge, live wells, and bait containers before leaving
a lake. This step is recommended for boaters on all waters and is required under
the emergency rules for boaters on the Great Lakes and the Mississippi River and
their tributaries up to the first dam.
Dispose of leftover bait in the trash, not in the water. Do not take live fish
or live fish eggs away from the boat landing.
Rinse boat and recreational equipment with hot water OR dry for at least five
· Report large numbers
of dead fish or fish with bloody spots to your local DNR fish biologist or conservation
Wisconsin already has taken steps to deal with VHS. The state
Natural Resources Board on Wednesday, April 4, unanimously passed emergency rules
prohibiting anglers and boaters from moving live fish, and requiring them to drain
their boats and livewells, before leaving Wisconsin's Great Lakes waters, the
Mississippi River and those waters' tributaries up to the first dam.
in Wisconsin is a $2.3 billion industry. More information on aquatic invasive
species and Wisconsin's programs to prevent their spread is available on the DNR
Questions and Answers on Viral Hemorrhagic Septicemia (VHS)
is VHS? What is the significance of the recent discovery of VHS in the Great Lakes?
Viral Hemorrhagic Septicemia is an infectious viral disease of fish that has been
found in fish from the Atlantic Coast of Europe and Atlantic and Pacific Coasts
of North America. Historically, VHS was known as a very serious disease of freshwater-reared
rainbow trout in Europe. At least four different genetic strains or forms of the
virus are known to exist. The North American marine strain has a relatively low
infection rate compared to that of the European freshwater strain. Until 2005,
VHS was only found in the marine environment in North America. Several fish kills
in the Lower Great Lakes since 2005 have been associated with VHS. To date, VHS
has been confirmed from wild fish in the Bay of Quinte Lake Ontario, Lake St.
Clair, Lake Erie and the St. Lawrence River. Scientists believe that this appearance
may represent an invasion of the freshwater strain in North America.
North American freshwater fish species are affected?
In the Great Lakes,
VHS has been found in smallmouth bass, yellow perch, crappie, muskellunge, northern
pike, bluegill, walleye, round gobies, sheepshead, and some sucker species. Scientists
are concerned; however, that VHS could also strike native salmonids such as trout,
salmon and whitefish in the wild, and salmonids in hatcheries and net pen operations.
did VHS get here?
It is unclear how the virus spread to the Great Lakes;
it is possible the marine virus may have been introduced to the Great Lakes some
time ago and it simply evolved to live in freshwater. The VHS virus is a strain
that undergoes rapid mutations (spontaneous genetic changes) and may have adapted
to freshwater environments in North America. Recently, VHS was found in stored
fish samples that were collected in the Great Lakes during 2003, suggesting the
virus has been present in the Great Lakes for some time.
does VHS spread?
It is unclear exactly how the disease is spread but
it appears that the virus can be shed by infected fish into the water through
metabolic waste materials, particularly by fish that survive the disease and become
carriers. It also appears that carrier fish or offspring of carriers become more
resistant to the disease. The virus can infect fish of all ages. It may enter
a host fish through the gills or food or contact with some contaminated object.
It does appear that stressed fish more vulnerable to viral infection. Typical
fish stressors include sudden water temperature changes, crowded hatchery conditions
and, spawning activity. The timing of the recent fish die-off in the Great Lakes
coincided with the spawning by some of the fish species, such as muskellunge.
does it do to fish? What are the symptoms of a fish with VHS infection?
Like many fish diseases, the type of symptoms present in a fish change with the
severity of the infection. At low infection intensity fish may display few to
no symptoms as is the case in most wild disease outbreaks. Hatchery or pen-reared
fish are much more susceptible because of the confined conditions. As the infection
severity increases, fish become darker and the eyes bulge with some bleeding around
the eye and base of the fins. The gills are usually quite pale with some pin point
bleeding. Mortalities appear at this point because hemorrhaging reduces the oxygen
carrying ability of the blood. Dark red patches may appear on the front and sides
of the head.
If the fish is opened
up, bleeding on the surfaces of the intestine, liver, swim bladder can be seen.
Fluid also builds up in the body cavity giving the fish a swollen belly. Later,
if infection increases, the body continues to darken and the eyes really stick
out of the head. At this point, the gills look gray or even white and the fish
may swim in a corkscrew pattern. Most fish kills from VHS occur in water temperatures
from 40 to 60 F (3-12 C) and few occur at temperatures above 62 F (15 C). NOTE:
The detection of a VHS infection can only be made from sophisticated laboratory
testing. A diagnosis cannot be made based solely on the observation of visible
signs because many different diseases of fish have very similar signs of disease.
is the long-term outlook for VHVS in the Great Lakes?
Diseases like VHS
run their course just as they do in human populations. At first mortalities may
appear to be large, but many biologists believe that most fish can survive the
disease if they are not otherwise stressed because mortalities generally occur
in weaker, stressed fish. The remainder will build up a natural immunity to the
virus and the numbers of fish killed by the virus will decline.
it a health risk to people?
There is no apparent health risk for
people contracting VHS. Because it takes a long time to identify the causes of
fish kills in lab studies, people should be cautioned against handling or eating
any fish that does not act or appear to be healthy because of the risk of contracting
avian botulism a bacterial disease that does pose a human health threat.
is being done to prevent the spread of VHS?
The state Natural Resources
Board passed Emergency Rules effective April 2007 require that boaters and anglers:
Note: In light of a preliminary positive test of two fish on Little Lake Butte
des Morts, the DNR is asking all boaters and anglers to immediately adopt these
practices on all state waters.
· Drain all water from your boat, trailer,
bait buckets, coolers, and other containers before you leave the landing or shore
fishing site location on Lake Michigan, Lake Superior, the Mississippi River or
· Do not transport live fish, including bait fish,
away from any Great Lakes or Mississippi River drainage landing or shore fishing
location. This includes tributaries up to the first dam.
· Do not
use "cut" or dead bait from other waters (except when fishing in Lake
Michigan, Green Bay, or tributaries).
· Do not use minnows unless
they were purchased from a Wisconsin bait dealer or you legally caught the minnows
from the place you are fishing.
In a hatchery, the best means of controlling
the disease is to prevent the contact of the virus and fish. This can be done
by hatchery disinfection, egg treatment with anti-viral agents, and using ultra-violet
light treatment of hatchery water. It is important to stock disease free fish
and to monitor freshwater populations for signs of further spread. Information
on diseased wild fish is difficult to obtain because they often die undetected
and fish can decompose rapidly making disease diagnoses very difficult. New research
is being developed that would allow more rapid detection of the disease.
should I do if I see a fish kill?
If you observe a fish kill on
the Great Lakes, please contact the Wisconsin Department of Natural Resources
at (608) 266-8782 or your local DNR office. If you see fish with any of the outward
signs of VHS as described above please mention this as well. This will help biologists
keep track of where the disease may be appearing.
questions and answers about VHS were developed by the University of Wisconsin
Sea Grant Institute and the Department of Natural Resources