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. Its
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 BASS
"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
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 another.
* 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
* Stage tournaments during cooler weather, so fish caught
will not be so stressed.
* Report dead or dying fish to state wildlife agencies.
* Volunteer to help agencies collect bass for LMBV
* 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: