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| Conservation
Issues |
Results of LMBV Workshop III Announced
B.A.S.S. Communications
LITTLE ROCK, Ark. - Largemouth Bass Virus (LMBV) seems to have lessened its grip on bass fisheries in the South.
That was one of several positive revelations from B.A.S.S.' Largemouth Bass Virus Workshop III staged here Feb.
22. Nearly 100 fisheries biologists and research scientists attended this annual session, which has become the
means by which state and federal wildlife agencies and universities share and compare the latest findings and anecdotal
information about the virus. Fewer fish kills attributable to LMBV were reported during 2001 than in the two previous
years, and those incidents were less severe than those in the past, state biologists said.
"The news is good from Alabama. It's been very quiet," said biologist Jerry Moss.
As evidence of the improved state of Southern fisheries, Dave Terre presented preliminary results that show only
45 of 899 adult-size largemouth bass sampled in LMBV-positive reservoirs in Texas were infected with the virus.
"Largemouth Bass Virus is just one of many challenges for managing bass populations, not the single one,"
added Tony Goldberg, a scientist at the University of Illinois.
Minor kills were reported in Arkansas, Georgia, Louisiana, Indiana, and Michigan. The latter two are of most significance
overall, because they further confirm that LMBV is not confined to Southern waters. During the summer of 2000,
biologists attributed a kill in Lake George on the Indiana-Michigan border to the virus. At that time, resource
managers had hoped that the Lake George incident was an aberration, and that LMBV would not be found in any additional
Northern fisheries. This past year, though, the virus was found in two lakes in Michigan, three in Indiana, and
two on the border, all in the same area. In addition, Illinois biologists confirmed the virus in fish from four
lakes, as well as some hatchery stocks, although no mortalities were linked to LMBV.
Among the many mysteries of LMBV is what triggers it to turn from an infection into a deadly disease; many of the
bass that test positive for the virus are otherwise healthy. Equally perplexing is how the virus is transmitted
from one fish to another and one lake to another. Dealing with such uncertainties, resource managers want to err
on the side of caution. "LMBV now is considered a significant, reportable pathogen," said Michigan's
John Hnath. "And we've requested that the virus be added to the list of diseases of concern for the Great
Lakes watershed." Elsewhere during the past six years, LMBV has been found in fish from Texas north to the
Missouri-Arkansas border, east to the Chesapeake Bay area, and south into Florida.
Until this year, the virus, which poses no threat to humans, was believed to have been first confirmed as an identifiable
virus at South Carolina's Santee Cooper Reservoir during 1995. But at this year's workshop, John Grizzle of Auburn
University cited evidence that the virus existed in Florida's Lake Weir in 1991. Scientists continue to debate
whether LMBV is a new phenomenon or has been around for years, killing bass but not being recognized as the culprit.
"What we do know is that this virus is not everywhere, as are some viruses," said Grizzle, emphasizing
the need to learn as much about the disease as quickly as possible so as better to contain it.
And more good news is that the learning curve should accelerate rapidly during the next few years, as more than
$400,000 from Wallop-Breaux (federal Sport Fish Restoration Program) is funding research at places such as Auburn,
Louisiana State, Mississippi State, and the Warm Springs Fish Health Center. Additionally, state agencies and other
universities are financing valuable work. Scientists are developing more sensitive and non-lethal ways to test
for the virus, as well as looking at how factors such as temperature, angling pressure, genetics and toxins might
trigger the virus to turn deadly. They also are examining potential non-lethal impacts, such as slower growth rates
among younger fish infected with the virus.
The latter could explain why fewer bass of 5 pounds or more are being caught in some states, but resource managers
are quick to add that much more data is needed to determine the cause. They add that while angling success has
declined in some lakes for a year or two following a die-off, no evidence exists that fisheries have been significantly
impacted. Other factors, they say, must be considered as well.
In Oklahoma, "we had the hardest winter in 20 years in 2001-2002, big shad kills in most lakes, a really long,
cool spring that altered water temperatures and stratification patterns, and extremes of high water and low water
- often on the same lake only months apart," said biologist Gene Gilliland.
"Throw in LMBV, and who knows how these things are affecting fish behavior." Such complications make
the mystery of LMBV that much more difficult to unravel, but they don't deter fisheries scientists in their research.
"LMBV may or may not be a problem, long-term," said Auburn's Grizzle. "We have no way of knowing
right now. That's why we need to do what we can as quickly as we can."
For more information contact B.A.S.S. Communications at (334) 272-9530. |
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