VIRUS SPREADS IN MICHIGAN
FOR IMMEDIATE RELEASE, 12 MAR 02
CONTACTS: John Hnath, 616-668-2132
Kelley Smith, 517-373-3375
LARGEMOUTH BASS VIRUS SPREADS IN MICHIGAN
ANGLERS URGED TO HELP PREVENT SPREAD OF DISEASE
LANSING--State resource officials today
announced that Largemouth Bass Virus appears to be spreading in southern
Michigan lakes, and called upon anglers to help contain the disease and
protect fish populations. Largemouth Bass Virus (LMBV) is one of
more than 100 naturally occurring viruses that affect fish, and is closely
related to viruses found in frogs and other amphibians. It's origin and
how it is spread are unknown. The virus is not known to infect humans, and
infected fish are considered safe to eat. However, it is recommended that
all fish should be thoroughly cooked as a precaution. In the fall of
2000, biologists from the Michigan and Indiana Departments of Natural
Resources discovered the presence of LMBV while jointly investigating a
die-off of largemouth bass in Lake George, located on the Michigan-Indiana
border near I-69. The discovery marked the first time LMBV had been
detected in either Michigan or Indiana and was the furthest north that the
virus had been detected in the United States. It was first discovered in
the Santee-Cooper Reservoir of South Carolina in 1995, following a die-off
of largemouth bass.
Since then, the virus has been detected in wild
fish from North Carolina, South Carolina, Florida, Georgia, Alabama,
Tennessee, Kentucky, Mississippi, Texas, Missouri, Arkansas, Indiana,
Illinois and Michigan. It is now confirmed that the virus in Lake
George was not an isolated event. LMBV has been found in another border
lake between Michigan and Indiana, two additional Michigan lakes and three
additional lakes in northern Indiana. The virus was also detected this
year in lakes and reservoirs in Illinois for the first time. Michigan DNR
Fish Pathologist John Hnath said LMBV appears to infect other fish
species, including smallmouth bass, bluegill and crappies, but has caused
mortality to only largemouth bass. Most fish mortalities associated with
the virus involve other stressors to the fish, including warm water
temperatures and heavy fishing pressure.
"The DNR cannot eradicate
this virus or treat affected wild fish populations," Hnath said.
"However, as we continue investigating this outbreak, we appreciate
receiving reports of unusual fish mortalities." Consistent with the
recommendations reported from the Largemouth Bass Virus Workshop III,
sponsored Feb. 22 by ESPN and BASS Federation, the DNR is calling on bass
clubs and others who target largemouth bass to voluntarily help reduce
angling stress on largemouth bass populations during warm weather. DNR
Fisheries Division Chief Kelley Smith noted the DNR will be monitoring
lakes in southern Michigan this summer, in partnership with the Michigan
"This disease has never been detected this far
north, and we still do not know how largemouth bass populations will be
affected in Michigan's lakes," Smith said. "We urge all members
of the angling community to help us monitor the waters. Further, we look
forward to working with our partners at the Michigan BASS Federation, and
appreciate their willingness to assist us in collecting information
necessary to better understand and manage this virus." There are few
outward signs that a fish has the virus. The virus has been found in many
lakes where there have not been reports of disease or mortalities of fish.
Affected fish usually appear normal, although they may be lethargic, swim
slowly and are less responsive to activity around them. Dying fish often
are seen near the surface and have difficulty remaining upright. Upon
internal examination, such fish usually will have bloated swim bladders,
which accounts for the cause of swimming problems. Red sores or other
lesions occasionally may be seen on the skin of the fish, but these are
secondary in nature and not part of the virus infection.
The DNR concurs with recommendations from the
LMBV Workshop III, and reminds anglers and boaters to take the following
steps to help prevent the spread of the virus:
- Clean boats, trailers, other equipment thoroughly
between fishing trips to keep from transporting LMBV, as well
as other undesirable pathogens and organisms, from one water body to
- Do not move fish or fish parts from one body of water to
another, and do not release live bait into any water body.
- Handle bass as gently as possible if you intend to release them.
- Stage tournaments during cooler weather, so fish caught will not be so
- Report dead or dying fish to state wildlife agencies.
- Volunteer to help agencies collect bass for LMBV monitoring.
- Educate other anglers about LMBV.
The Michigan DNR will continue to communicate any new
information learned about the disease in Michigan. The following internet
site offers more information: