No largemouth bass virus found upstream of Pool 3 in Mississippi River
Largemouth Bass Virus, which was discovered in the Mississippi River
south of the Twin Cities last year, has shown no evidence of spreading
upstream, according to the Minnesota Department of Natural Resources (DNR).
Joe Marcino, a pathologist with the DNR's Ecological Services Division, said
DNA tests showed no sign of the virus in 60 largemouth and smallmouth bass
collected between Little Falls and St. Paul this fall.
The disease was discovered last year in fish collected by the U.S. Fish and
Wildlife Service from Mississippi River in Pool 3 (near Red Wing) and Pool 7
(southeast of Winona). Largemouth Bass Virus has killed largemouth bass in
more than 24 locations nationwide. However, it does not kill entire
largemouth populations. Surveys on lakes following a kill suggest fish
populations remain within normal ranges.
Other members of the sunfish family known to become infected with the virus
include the spotted bass, Suwanee bass, bluegill, redbreast sunfish, white
crappie and black crappie. So far, the virus has proved fatal only to
"There is no evidence that Largemouth Bass Virus has killed any fish in
Minnesota," Marcino said.
"We're very pleased not to find evidence that the disease has moved
upstream," Marcino added. "We will continue to monitor fish populations in
the Mississippi, inland lakes and private hatcheries for Largemouth Bass
Virus and several other diseases."
The Minnesota DNR fish and wildlife pathology laboratory has been testing
fish for the disease for the last two years. Largemouth and smallmouth bass
from state and private fish hatcheries have been examined for the presence
of the virus. The disease has also not been detected in Minnesota's inland
Infected fish are safe to handle and eat. Largemouth Bass Virus is one of
more than 100 naturally occurring viruses that affect fish but not humans or
warm-blooded animals. Its origin is unknown, but it is related to a virus
found in frogs and other amphibians. It is nearly identical to a virus
isolated in fish imported to the United States for the aquarium trade.
Anglers can help prevent the spread of Largemouth Bass Virus, other fish
diseases, and the spread of exotic species by taking the following steps:
• do not transport live fish and stock them in another water body; a permit
is required to transport and stock live fish in Minnesota
• remove visible plants and animals from boats, trailers and other boating
equipment before leaving any water body
• drain water from the motor, live well, bilge and transom wells at the ramp
access before leaving any water body
• dispose of unwanted minnows and leeches on shore; never release live bait
into a water body, or release aquatic animals from one water body into
another water body
• wash and dry boats and other boating equipment that normally gets wet in
order to kill exotics and pathogens that were not visible at the boat
launch. Recent research has determined that Largemouth Bass Virus can live
for several hours in water, confirming the importance of this practice.
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