Bass virus in Michigan – 07/30/2004

  • October 1, 2013 at 3:09 am #548

    by Babe Winkelman
    The Pilot-Independent
    Last Updated: Friday, July 30th, 2004 12:42:21 PM

    In an age in which state fish and wildlife managers are loathe to
    restrict opportunity, fisheries officials in Michigan are asking the
    state’s largemouth bass anglers to heed an unlikely request: to stop

    That’s right, the Michigan Department of Natural Resources has called
    on anglers who target largemouth bass to voluntarily refrain from
    fishing during the heat of summer, in attempt to reduce angling
    stress on bass populations.

    The reason: the continued spread of Largemouth Bass Virus (LMBV),
    which is said to be one of 100 naturally occurring viruses that
    affect fish but whose origins are unknown. The virus, which has
    caused largemouth bass die-offs throughout parts of the United
    States, is related to those found in frogs and other amphibians and
    is nearly identical to a virus isolated in fish imported to the
    United States via the aquarium trade.

    Last month, the Michigan DNR announced that LMBV “continues to
    spread” in lakes in southern Michigan, which prompted fisheries
    officials to make the public request.

    “We’re asking that they (anglers) voluntarily forgo bass fishing from
    July 15 to Aug. 15, which is generally the peak of summertime
    temperatures and when the highest incidents of mortality occur,” said
    Gary Whelan, DNR fish production manager. “Remember that the request
    is voluntary. This is something anglers can do to protect the state’s
    largemouth bass population and to ensure healthy populations in the
    future. It’s common sense.”

    LMBV was first detected in Michigan waters in the fall of 2000 in
    Lake George, which is on the Michigan-Indiana border. From earlier
    research and surveys conducted by the DNR in 2002 and 2003, the virus
    has been confirmed in 15 of 30 lakes examined, according to the
    Michigan DNR. “The DNR cannot eradicate this virus or treat affected
    wild fish populations,” Whelan said.

    “However, as we continue investigating this disease, we appreciate
    receiving reports of unusual fish moralities.”

    The disease was first discovered in South Carolina’s Santee-Cooper
    Reservoir in 1995 following a die-off of largemouth bass. To date,
    the virus has been found in wild fish in as many as 19 states, in
    lakes and impoundment’s from Texas east to the Chesapeake Bay area,
    north as far as Vermont, and south into Florida.

    When LMBV was first discovered, fisheries biologists worried that the
    disease could have far-reaching ramifications for largemouth bass
    populations, that largemouth bass fishing could be in jeopardy.

    However, it appears that those dire predictions were largely
    exaggerated. In most instances, fisheries biologists say, die-offs of
    adult fish associated with the disease impact roughly 10 percent in a
    given body of water. The bottom line is that researchers believe that
    LMBV-related deaths appear to be minor compared to kills prompted by
    pollution and other environmental-related problems.

    The wild card for researchers is that most LMBV-infected bass appear
    completely normal. It’s not until the virus triggers the disease that
    the fish begin to exhibit signs of impairment, including difficulty
    swimming. It is believed that LMBV attacks the swim bladder, causing
    fish to lose their “bouncy control.” In addition, some fish appear to
    be bloated.

    What’s known for certain is that most of the die-offs occurs from
    June through September, when surface water temperatures, particularly
    in the south, are highest.

    According to Whelan, mortality occurs when largemouth bass are most
    stressed. Potential stressors could include a combination of factors:
    very hot weather, high angling pressure, poor water quality, crowding
    in livewells and tanks, and other pathogens.

    “Any measure that can be taken to minimize stress on these fish will
    reduce the impact of the disease and mortality,” Whelan said. “That’s
    why we’re asking anglers to voluntarily stop fishing during that
    month period.”

    While research on LMBV continues throughout the country, including
    Michigan State University, the disease is still largely a mystery. It
    is not known to infect humans, and infected fish are considered safe
    to eat, though they should be thoroughly cooked, fisheries officials

    Most researchers believe that the disease will remain in lakes and
    impoundments and impose added pressure on bass populations. Still,
    there is no evidence that LMBV has caused any long-term damage to any
    largemouth bass fishery — at least to date.

    For now, researchers say the best course of action is to stop the
    virus from spreading into other bodies of water. Here are a few tips
    that anglers should follow to prevent the spread.
    • Clean boats, trailers and other equipment thoroughly between
    fishing trips.
    • Do not move fish or fish parts from one body of water to another,
    and do not release live bait into any body of water.
    • Handle bass as gently as possible if you intend to release them. As
    always, all fish should be released as soon as possible.
    • If you intend to release fish, refrain from hauling them for long
    periods in live wells.
    • Minimize targeting largemouth bass during very hot weather
    • Report dead or dying largemouth bass to your state natural
    resources agency.
    • Educate other anglers about LMBV.

    Babe Winkelman is a nationally known outdoorsman. Watch his award-
    winning “Good Fishing” television show on Outdoor Channel, WGN-TV,
    and the USA Network.

The forum ‘Strange Animal Deaths’ is closed to new topics and replies.