Virus Killing Great Lakes Giants

  • Fishing guide Rich Clarke of Clayton, NY, is famous for muskie hunts. He's worried so many adult muskies are falling victim to VHS. (Photo courtesy of Rich Clarke)

Fall is when avid anglers flock to the Great Lakes for one of the most
challenging freshwater catches: the muskellunge, or muskie. Some call it
“the fish of 10,000 casts.” This year’s muskie season is clouded by bad news
of a new fish disease and invasive species crowding muskie habitat. David
Sommerstein reports scientists are watching this top-of-the-food-chain
species carefully:

Transcript

Fall is when avid anglers flock to the Great Lakes for one of the most
challenging freshwater catches: the muskellunge, or muskie. Some call it
“the fish of 10,000 casts.” This year’s muskie season is clouded by bad news
of a new fish disease and invasive species crowding muskie habitat. David
Sommerstein reports scientists are watching this top-of-the-food-chain
species carefully:




It’s a cool afternoon as fishing guide Rich Clarke fillets the day’s catch:


“Went out, caught some northerns, a few bass, some jack perch. Had a
pretty good morning.”


Clarke’s specialty is hunting for muskies, 60 pound fish with a lot of fight:


“I mean, the rod screams, they yank, yank, and yank. It doesn’t come all that
often, but when it comes, it’s one of the most exciting things you’ll see when
you fish in fresh water.”


Clarke worries that magical hit might become even more rare. Since 2005,
several hundred of those prized muskies were found belly-up dead, victims
of viral hemorrhagic septicimia, or VHS.


(Sound of hose)


Clarke washes down his fillet table. He mutters VHS is just another non-
native organism threatening the muskie. There are already more than 180
invasive species in the Great Lakes-St. Lawrence River system:


“Everything from the goby to the , y’know, and weed species and all
sorts of stuff, spiny water fleas, you name it, all sorts of stuff that are not native to this
waterway that we have to deal with, and it changes the whole ecology.”


A new invasive species is found every six to nine months. Scientists can
barely keep up in understanding the impact on the native environment.




In a nearby bay of the St. Lawrence River in northern New York State,
Roger Klindt, John Farrell, and a crew drag a huge net through the water:


“We’ve got two people pulling it slowly through the vegetation just trying
to basically corral fish.”


This is called seining, getting a sample of all the fish that live here. Klindt
and Farrell have been doing this in the same marshy shallows for more than
20 years. And Farrell says what they’ve found this year is disturbing:


“Muskellunge numbers in the index are at their lowest levels on record since
we’ve been collecting data.”


Down from almost 50 in the spring spawning run of 2003 to just 4 this year.
Farrell’s a researcher with the State University of New York Environmental
Science and Forestry. He says this could be the result of VHS killing so
many adult muskies in their reproductive prime.




Yet another invasive species is also troubling, the round goby. It’s an ugly
little fish from Eastern Europe that breeds like crazy. Farrell and Klindt
count minnows flipping and fluttering in the seining net:


“15 black gins, 8 blunt nose, 5 spot tail.”


“I didn’t actually count things, I was just picking gobies.”


Farrell says they’ve found more round gobies in these marshes than ever
before:


“Which is a bit of a surprise to us.”


Now the muskie young have to compete with round gobies for food:


“How these species are going to respond to the presence of gobies is
unknown at this time, but they have high predation rates, they’re very
prolific, becoming extremely abundant, so the food web in this system is
shifting.”


This is what frustrates people who study invasive species. Once researchers
train their focus on one, like the fish disease VHS, another emerges to
confound the equation. Roger Klindt is with New York’s Department of
Environmental Conservation
:


“Change happens, y’know, nothing stays the same forever. But when we
have invasive species and exotic species come in, the change is often so
rapid that native species can’t adapt to it.”


That talk makes anglers nervous. Peter Emerson’s been fishing around here
for years. In fact, he participated in a catch and release program that brought
muskie populations back to health in the 1980s:


“There was a real bonanza, til this virus showed up. I’m hopeful they don’t
go extinct.”


Biologists expect adult muskies that survived VHS will develop resistance to
the disease. But they fear the next generation won’t inherit the immunity,
causing more die-offs of one of America’s most prized freshwater fish.


For The Environment Report, I’m David Sommerstein.

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Fish Disease Spreads to New Waters

  • The external bleeding on this freshwater drum fish is a result of VHS. The disease is spreading beyond the eastern Great Lakes region. (Photo by John Lumsden, University of Guelph)

A virus that’s been killing fish in the Great Lakes is spreading to
other waterways in the US. Chuck Quirmbach reports:

Transcript

A virus that’s been killing fish in the Great Lakes is spreading to
other waterways in the US. Chuck Quirmbach reports:


Viral hemorrhagic septicemia has been limited to the eastern Great
Lakes region, but now it’s gotten into a forty-mile long lake in
Wisconsin. Lake Winnebago draws anglers from a wide area.


Mike Schmal is a local tourism official. He says the fish-killing
virus could be very disruptive.


“There’s numerous bait shops and numerous businesses that depend on the
lake and this is our summer leisure season… when the boating season
begins and when sportfishing begins.”


Scientists say it appears to be impossible to get the virus out of
infected waters, so natural resource officials are trying to stop VHS
from being spread to more lakes and rivers in other states.


It’s not clear how VHS got into the US, though contaminated
ballast water from international ships is one possibility.


For the Environment Report, I’m Chuck Quirmbach.

Related Links

Great Lakes Fish “Quarantined” by Usda

Regulators are worried about a fish disease found in the lakes that could spread to other areas. Federal officials are trying to figure out the next step after banning certain shipments of fish in the Great Lakes Region. Dustin Dwyer has more:

Transcript

Regulators are worried about a fish disease found in the lakes that could spread to other areas. Federal officials are trying to figure out the next step after banning certain shipments of fish in the Great Lakes Region. Dustin Dwyer has more:


The disease is called viral hemorrhagic septicemia. It can cause fish to bleed internally and die.


The disease is harmless to humans, but federal regulators say it could lead to massive die-offs for up to 37 different species of fish, so they’ve stopped fisheries in the eight Great Lakes states, and two Canadian provinces from shipping those species over state lines. The ban only affects live fish.


Jim Rogers is a spokesman with the US Department of Agriculture. He says the ban is meant to stop the spread of the disease while officials figure out what to do next.


“Now eventually that federal ban is going to lift, and we are going to be allowing movement. But right now we just can’t do it with the threat of this disease hanging over us.”


The fishing industry in the Great Lakes has been valued at more than $4 billion a year.


For the Environment Report, I’m Dustin Dwyer.

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