Let's talk about the impact of largemouth bass virus

Bass in several Virginia impoundments, including Smith Mountain Lake, are being impacted by largemouth bass virus (LMBv), but anglers give little indication of being overly alarmed. That's as it should be. LMBv appears to be a disease we can get along with.

"The good news: The fisheries usually do make a complete or near complete recovery," said Dan Wilson, fisheries biologist for the Department of Game and Inland Fisheries.

The bad news: The virus can hang around for 4 or 5 years. Bass anglers aren't expected to see their catch rates significantly decline; rather, they can expect to catch fewer big bass, especially 18- to 20-inch fish, Wilson said.

The number of adult bass in Smith Mountain Lake has looked good for several years, so Wilson was surprised while working up data last fall that revealed bass bigger than 15 inches had declined 16 percent in 2012 and bass 20 inches and longer were down 55-percent.

It is possible the declines were the result of inherent sampling variables, Wilson said, but he doubts that.

"Most likely the decline is due to LMBv," he said.

Even accomplished anglers appear to be unaware of the virus and its impact, so let's take a closer look at what we are up against.

Where LMBv is found

The virus first was discovered in Lake Weir, Florida in 1991. The first reported fish kill as a result of the disease occurred four years later at Santee Cooper Reservoir in South Carolina. From there, the virus spread across the southern United States.

In addition to 20,000 acre Smith Mountain Lake, several impoundments in Virginia that have been impacted include Kerr Lake where biologists report the density of bass larger than 4 pounds has declined. This helps explain the feeling of many anglers that bass fishing in 50,000 acre Kerr simply isn't what it once was.

The once spectacular trophy bass fishing at Briery Creek Lake has fallen on hard times since the early 2000s. Biologists blame that on LMBv.

In 2011, DGIF researchers tested 16 bodies of water, including large impoundments, small impoundments and major rivers. LMBv was detected in all but one, the tidal James River. Included were Lake Anna, Chesdin Lake and Sandy River Reservoir.

Impact of LMBv

"In most cases, the initial impact of LMBv is that big bass die at a little higher rate and growth slows a little," Wilson said. "While these two factors independently do not seem like a big deal, the two combined cause a reduction in larger fish."

Since big bass are fewer, this means greater numbers of 8- to 12-inch young bass, which give the appearance that everything is healthy.

You get an idea of the drought of large bass in Smith Mountain when you look at the recent Oakley Big Bass Tour which attracted 670 bass anglers and none was able to land a citation-size (8 pound-plus) largemouth. The winning fish was less than 6.5 pounds. The past weekend, Roanoke Valley Optimist Club and Challenger Little League Baseball tournament dew about 450 entrants. The top largemouth was 7.32 pounds.

The good news of LMBv

Officials say that bass normally build up immunity to the disease. The reservoirs in the southern states that were hit hard in the late 1990s have recovered to pre-exposure angling success rates.

"Another good note, our 2013 sampling (at Smith Mountain Lake) seems to be showing that things seem to be leveling off or at least not getting worse," Wilson said.

There is no cure for the disease. The virus must run its course. Anglers can help limit its impact by refraining from holding tournaments during the heat of the summer when bass are under stress, and by not releasing bass in one body of water that have been caught in another, officials say.

The disease poses no threat to human health.

Your comments welcome: xtrails@earthlink.net

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