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.

Related Links

New Fish Virus Becoming Long-Term Threat?

Biologists are concerned a new fish virus may become an ongoing threat in the Great Lakes. The virus caused a fish die-off in Lake Ontario and the St. Lawrence River last month. The GLRC’s David Sommerstein reports:

Transcript

Biologists are concerned a new fish virus may become an ongoing threat in the Great Lakes.
The virus caused a fish die-off in Lake Ontario and the St. Lawrence River last month.
The GLRC’s David Sommerstein reports:


Viral Hemorrhagic Septicemia is common in saltwater fish in the Pacific Northwest,
but somehow the virus hopped into the freshwater fish of Lake St. Clair and Lake Ontario
last year. Then, last month, the virus killed hundreds of fish in the St. Lawrence River.
Scientists are trying to determine if the virus is a long-term threat to the Great Lakes
fishery:


“You know, that’s kind of the million dollar question.”


John Farrell directs the Thousand Islands Biological Station. He says many
fish species may become infected with the virus but not show symptoms:


“They may serve as a reservior for the virus. There’s a potential
that the virus could cycle over time, but may be with us for a long time to come.”


Conservation officials are most worried about muskies, trout and salmon – native
fish that anglers love to catch.


For the GLRC, I’m David Sommerstein.

Related Links

Brighter Future for Native Trout

Anglers in Lake Superior are looking forward to the return of the coaster brook trout. The native trout was fished nearly to extinction in the early 1900s. New efforts to help the remaining populations rebound are attracting the interest of fisheries managers around the Great Lakes. The Great Lakes Radio Consortium’s Stephanie Hemphill has the story:

Transcript

Anglers in Lake Superior are looking forward to the return of the coaster brook trout. The native trout was fished nearly to extinction in the early 1900s. New efforts to help the remaining populations rebound are attracting the interest of fisheries managers around the Great Lakes. The Great Lakes Radio Consortium’s Stephanie Hemphill reports:


The French River tumbles into Lake Superior about 15 miles from Duluth. It’s a popular fishing spot, and people are catching rainbow trout. Rainbows are not native to Lake Superior. The Minnesota Department of Natural Resources stocks them from the fish hatchery across the road.


People used to catch coaster brook trout here, but
there aren’t many of the fish around anymore.


“I haven’t seen one of those in years.”


“There aren’t any coaster brook trout. You’re dreaming.”


“‘You very seldom get them, but when you do they’re nice.’ Hemphill: ‘Why are they nice?’  ‘They’re so nice and clean, the colors are so beautiful.’ Hemphill: ‘Are they good eating?’ ‘Oh-h-h, there isn’t any better.'”


For a freshwater fish, coasters are colorful. Their sides are sprinkled with bright red dots. Their fins are edged with a bright white line. When they spawn, their bellies turn iridescent orange.


They hatch in rivers, and then swim downstream to grow up in the lake. They return to the river to spawn.


There used to be lots of coasters around Lake Superior, and in northern Lake Michigan and Lake Huron. They were a popular sport fish. In the 1850s, people came from all over to catch them. By the early 1900s coasters had practically disappeared.


Don Schreiner is the Department of Natural Resources fisheries supervisor in this part of Minnesota. He says coasters are fairly easy to catch. And that’s why they almost disappeared.


“There were no roads up here, people came in by boat, they came in by train. There’s accounts of people standing on the shore and on the riverbank and catching hundreds of brook trout.”


After the fishermen, lumberjacks came. They cut down the big trees that shaded the streams. They floated timber down the rivers, eroding the banks. Now these rivers are much more susceptible to flooding and sedimentation. The coaster brook trout need a rocky bottom, not a mud bottom, to spawn.


Then the state began stocking other fish here, so anglers would have something to catch. Pacific salmon, European brown trout. They compete with the few native brook trout that still survive in Lake Superior streams.


Some people want to try to restore the native brook trout. But others like to catch the big salmon, and the feisty rainbows. Don Schreiner says the DNR has to balance those competing demands.


“I think everybody cares about coaster brook trout as long as it doesn’t cost them anything personally. If I have to give up my favorite species in favor of a coaster brook trout, I might not be willing to do that. That’s the sort of thing we see.”


Angling restrictions imposed in the last few years have helped the trout. Schreiner says it’s possible they’ll bounce back, if people leave them alone, but improving the habitat is also key. That could take 50 years.


Some groups are trying to push things along a little faster.


The Red Cliff Tribal Fish Hatchery near Bayfield Wisconsin specializes in rearing coaster brook trout. Every year a million eggs are hatched here.


“Inside this building is where we keep our adult brood stock fish.”


Greg Fischer is the hatchery manager. He says they raise some fish for a year and a half before releasing them. Workers mark these fish to keep track of them in the wild.


“We have fin clipping parties where for several days we fin-clip each one of the fish, and when we’re stocking anywhere from 50 to 80,000 of these larger fish a year, that’s a lot of marking”


Some coasters from the hatchery might find a home at Whittlesey Creek near Ashland, Wisconsin. The U.S. Fish and Wildlife Service is turning Whittlesey Creek into a refuge for coaster brook trout.


Biologist Lee Newman says it’s a promising spot for spawning. Springs seep up through the gravel bottom. That provides the eggs with a constant flow of oxygen. Newman wants to plant eggs and very young fry directly over the springs. That’s what they did on the Grand Portage Chippewa reservation in Minnesota. And Newman says it worked there.


“We’ve captured pairs of adults that were radio tagged and captured on their spawning beds, and two years later catch the exact same pair on the exact same spawning beds, indicating that they are returning precisely to their home locations.”


Newman says when the fish are very young they can imprint on the chemistry of the stream, and find their way back years later.


Biologists still have a lot of questions about how to help the coaster brook trout. But right now, at least, its future looks a little brighter. For the Great Lakes Radio Consortium, I’m Stephanie Hemphill.