Tests showing VHS hasn’t spread to more state waters

DNR Report

Madison – All planned testing of wild fish for VHS fish disease
has been completed for 2008, and results show that – so far – the
deadly fish virus has not spread in Wisconsin and that state waters
have not suffered the kind of fish kills once feared, according to
DNR officials.

Fish from 67 different waters were tested for VHS in 2008, and
the only positives were found in fish from Lake Michigan, where VHS
already was known to exist. Round gobies found washed ashore on a
Milwaukee Beach in June and yellow perch collected a short while
later both tested positive. The diagnosis of VHS in the round
gobies, an invasive fish species, represents the only instance this
year in Wisconsin in which VHS was diagnosed as the cause of a fish
kill.

“This is good news on all fronts,” said Wisconsin DNR Fisheries
Director Mike Staggs. “There was a lot of concern in 2007 that VHS
was already widespread in Wisconsin and that it would spread
rapidly. Based on the sampling we’ve done last year and this year,
it’s clear that’s not the case, and that’s a very good thing.”

Staggs said the test results affirm the DNR’s rules for boaters,
anglers, and people who harvest wild bait are working to avoid
spreading the disease.

VHS prevention

“We thought the virus could be contained if we could get boaters
and anglers to drain their boats and not move live fish,” Staggs
said. “It seems we’ve been successful and we’re thankful for the
public response. We need boaters and anglers to keep up the good
work now and in the future to contain VHS and other invasive
species.”

VHS, or viral hemorrhagic septicemia, first was detected in
Wisconsin in Lake Winnebago system waters in May 2007 and later
that month in Lake Michigan system waters. None of the other 50
waters tested that year were positive for VHS.

The virus does not affect humans, but it can infect dozens of
fish species, can spread rapidly (fish to fish and through the
water), and it caused large fish kills in 2005 and 2006 in the
lower Great Lakes.

To assess the prevalence of the disease in Wisconsin in 2008,
DNR fisheries crews collected fish from 67 waters for testing by
the Wisconsin Veterinary Diagnostic Laboratory in Madison, the La
Crosse Fish Health Center, and Microtechnologies, a private lab in
Maine, said Tim Simonson, the fish biologist who has been
coordinating DNR’s VHS surveillance efforts.

VHS distribution

Most of the work was done at the same time DNR crews were
conducting fish population surveys in April and May, and when water
temperatures were below 60 degrees Fahrenheit – when the virus is
most active. The fish collected for testing included walleyes,
muskies, smallmouth bass, and yellow perch, all angler favorites
and all species that are among the most susceptible to VHS.

“The samples had to be collected during a short period when the
water temperatures were right, and processed immediately,” Simonson
said. “Our fisheries staff did a tremendous job getting this work
done on top of their already scheduled fish-sampling
activities.”

All of the VHS-sampled fish were tested for one of three
reasons: as part of the DNR’s planned surveillance for VHS that was
funded in part by a federal grant; because the fish had symptoms
consistent with VHS; and as part of DNR’s efforts to keep VHS and
other diseases out of the state hatchery system. Reproductive
fluids from all wild game fish that were spawned in spring to
supply eggs for the hatcheries were screened for VHS and other
viruses.

Waters tested included popular, high-traffic waters such as Lake
Du Bay, the Wisconsin River at several locations, the Minocqua
Chain of Lakes, Little St. Germain Lake, Lake Kegonsa, Lake
Koshkonong, the Willow Flowage, the Gile Flowage, and Lac Courte
Oreilles.

“We can’t say with 100-percent certainty that VHS is not
somewhere outside these known waters, but it’s certainly not
prevalent,” Simonson said. “We’ve looked at so many different
places and so many different watersheds.”

Test results of fish taken from several Lake Winnebago and Fox
River waters tested negative for VHS, including Little Lake Butte
des Morts and the Wolf River in Waupaca County.

The DNR is seeking another federal grant to help pay for VHS
monitoring next year; waters planned for the project will be
scattered across the state to continue to assess the prevalence of
VHS.

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