A popular fish might be making a comeback in the upper Great Lakes. Yellow perch were once a favorite catch for sport and commercial fishermen, but their populations crashed in the 1990’s. Biologists say new surveys in Lakes Huron and Michigan have found huge numbers of young perch. The GLRC’s Peter Payette reports:
Transcript
A popular fish might be making a comeback in the upper Great Lakes.
Yellow Perch were once a favorite catch for sport and commercial
fishermen, but their populations crashed in the 1990’s. Biologists say
new surveys in Lakes Huron and Michigan have found huge numbers of
young perch. The GLRC’s Peter Payette reports:
A survey of Lake Michigan found more perch were born last year than in
the best years on record. Two or three times as many.
Recent studies of perch in Lake Huron’s Saginaw Bay have shown
similar results. It’s not clear why fish numbers would suddenly
skyrocket. Weather is believed to be one factor.
Dave Fielder is a biologist with the Michigan DNR. He says perch in
Lake Huron have also benefited from the decline of alewives, which are
an invasive species.
“We’ve known for a long time that alewives are formidable predators and
competitors on newly hatched yellow perch fry.”
Fielder says most of the newborn perch are not surviving so the adult
population in Saginaw Bay has not grown. He says it may be too many
perch have been born and there’s not enough food for them all.
Asian carp are one of the invasive species featured in the exhibits in your local museums. (Photo courtesy of USFWS)
The zebra mussel is another invasive species that is hurting the Great Lakes' natural food chain. (Photo courtesy of USGS)
Big, public aquariums spend a lot of money to make fish look like they’re at home in the wild. But lately some aquariums are showing fish that are out of place. The GLRC’s Shawn Allee looks at one aquarium’s effort to give them the spotlight, too:
Transcript
Big, public aquariums spend a lot of money to make fish look like
they’re at home in the wild, but lately some aquariums are showing fish
that are out of place. The GLRC’s Shawn Allee looks at one aquarium’s
effort to give them the spotlight, too:
The federal government’s spending millions to keep Asian Carp out of
the Great Lakes. Biologists worry Asian Carp could devastate the lakes’
ecosystem. Recently, though, several carp were brought within sight of
the Great Lakes, and biologists are happy about it.
Chicago’s Shedd Aquarium is on the shore of Lake Michigan. It’s
holding an exhibit of Asian Carp and other alien invasive species.
Curator Kurt Hettinger captured the aquarium’s carp during a trip on an
Illinois river.
“They’re literally jumping, sometimes over the bow of the boat,
sometimes smacking into the side of the boat. I just looked behind me
and was amazed to see all these fish jumping in the wake of the boat, and
to this day, I’m still stunned by this.”
And Hettinger’s more than just stunned. He’s worried.
Asian Carp are an invasive species, basically … pests that crowd out
native fish, and that river where he caught them hooks up to Lake
Michigan.
Again, Asian carp haven’t made it to the Great Lakes, but more than one
hundred and sixty other invasive species have arrived and are breeding
quickly.
One example’s the zebra mussel. At first, scientists worried about how
much money it could cost us. Zebra mussels multiply so fast they can
block pipes that carry cooling water to power plants. But now, we know
the zebra mussel’s disrupting the lakes’ natural food chain.
In other words, invasive species are a huge economic and ecological
nuisance. That’s why the Shedd Aquarium started the exhibit.
“The public I think has seen enough stories about the damages and the
spread and the harmfulness, but those stories are not very often coupled
with solutions.”
That’s ecologist David Lodge. He says the exhibit tries to show how
people spread these species around. Lodge points to one exhibit tank. It
looks like a typical backyard water garden. It’s decked out with a small
fishpond, water lilies, even a little fountain shaped like an angel. It looks
pretty innocent, but Lodge says plants and fish you buy for your own
water garden could be invasive species.
“All those plants and animals that are put outside, then have an
opportunity to spread. Now, it doesn’t happen very often, but with the
number of water gardens, it happens enough so that they are a serious
threat to the spread of species.”
Birds or even a quick flood could move seeds or minnows from your
garden to a nearby lake or river.
The Shedd Aquarium’s not alone in spotlighting invasive species.
Several aquariums and science museums are also getting on board. For example one in
Florida shows how invasive species have infested the Everglades.
Shedd curator George Parsons went far and wide for inspiration.
“I was in Japan last year when we were planning this, and I just
happened to stumble across one of their aquariums and they had an
invasive species exhibit, except that they were talking about large mouth
bass and blue gill. You know, something that is our natives. So, it was
kind of ironic to see that out there. It was kind of neat.”
Like us, the Japanese take invasive species seriously. Back in 1999 the
humble Midwestern Blue Gill created a national uproar. Turns out, they
had taken over ponds throughout the Emperor’s palace, and how did the
bluegill get to Japan?
Probably as a gift from a former Chicago mayor. Apparently, the mayor
thought blue gill might make nice sport fishing in Japan. It was an
innocent mistake, but it’s just the kind of mishap biologists want all of us
to avoid from now on.
Some groups are looking for ways to reduce the damage to natural areas done by off-road vehicles. An organization representing off-road riders agrees that there should be rules for off-roading… but not complete bans on the recreational vehicles. The Great Lakes Radio Consortium’s Lester Graham
reports:
Transcript
Some groups are looking for ways to reduce the damage to natural areas
done by off-road vehicles. An organization representing off-road riders
agrees that there should be rules for off-roading… but not complete bans
on the recreational vehicles. The Great Lakes Radio Consortium’s Lester
Graham reports:
Off-road riding is a lot of fun for a lot of people, but some environmental
groups want off-road vehicles banned in many state and national parks.
For example, one study is looking at banning off-road vehicles from
some sand dunes on Lake Michigan because they damage rare plants.
Russ Ehnes is with the riders’ group the National Off-Highway Vehicle
Conservation Council.
“We all need to be sensitive when it comes to threatened and endangered
species and habitat, but we need to also find ways to provide
opportunities instead of just eliminating opportunities.”
Ehnes concedes as the number of off-road riders has increased, damage
to natural areas has worsened. He says it’s up to the park managers,
though, to find a way for everyone, including riders, to enjoy the parks
and preserve the important habitat.
Illinois has joined the ranks of states that say federal mercury standards don’t go far enough. Governor Rod Blagojevich says he’ll tighten restrictions on his state’s 22 coal-burning plants. The Great Lakes Radio Consortium’s Robert Wildeboer reports:
Transcript
Illinois has joined the ranks of states that say federal mercury standards
don’t go far enough. Governor Rod Blagojevich says he’ll tighten
restrictions on his state’s 22 coal burning plants. The Great Lakes Radio
Consortium’s Robert Wildeboer reports:
Democratic Governor Rod Blagojevich says he first became aware of the
dangers of mercury when his pregnant wife began limiting how much
fish she ate.
Coal-burning plants emit Mercury into the atmosphere. It eventually
ends up in the water supply, contaminating fish.
Blagojevich says current federal standards are inadequate. He wants
plants to contain 90 percent of the mercury pollution they create within 6
years.
“What we’re doing here today is protecting Lake Michigan. Our Lake.
Not just the lake of the city of Chicago, not just the lake of those of us
who live in Illinois, but the Lake that our whole country has come to rely
on and it’s critical for us to protect our natural resources, our lakes and
our rivers and our streams.”
Blagojevich says his proposed standards are among the toughest in the
nation. Critics say the extra financial burden could cause businesses to
move to neighboring states, but Blagojevich says he hopes other Great
Lakes states adopt similar measures.
For the GLRC, I’m Robert Wildeboer.
Host tag:
Illinois won’t adopt the proposed rules until they are approved by a state
legislative committee.
Lake Michigan dunes with a power plant in the background. (Photo courtesy of EPA)
In some places, creeks wash bacteria into the lakes on or very near swimming beaches, making contracting E. coli a greater threat. (Photo by Lester Graham)
A sewage treatment plant in Chicago, Illinois. (Photo courtesy of
EPA)
If you swim or play on the beaches around the Great Lakes, you’ve
probably heard about ‘beach closings.’ At best, the situation is an inconvenience.
At worst, it’s a serious health risk for some people. That’s because the
beaches are closed due to dangerous levels of bacteria in the water.
Beach closures are not all that new, but Shawn Allee reports… the
science behind them could change dramatically in the next few years:
Transcript
We’re continuing our series, Ten Threats to the Great Lakes. Our field guide through the series is Lester Graham. He says anyone who visits Great Lakes beach is familiar with one of the Ten Threats.
If you swim or play on the beaches around the Great Lakes, you’ve
probably heard about ‘beach closings.’ At best, the situation is an inconvenience.
At worst, it’s a serious health risk for some people. That’s because the
beaches are closed due to dangerous levels of bacteria in the water.
Beach closures are not all that new, but Shawn Allee reports… the
science behind them could change dramatically in the next few years:
(Sound of dog and beach)
During the summer, dogs and their owners usually play together in the
water along this Lake Michigan beach, but today, several dog owners
scowl from the sand while their dogs splash around.
“It’s e coli day … it’s a hardship.”
This beachgoer’s upset, and like she said, e coli’s to blame.
Park officials tested the water the previous day and found high levels of
the bacterium. Missing a little fun on the beach doesn’t sound like a big
deal, but there’s more at stake than recreation.
Cameron Davis is with the Alliance for the Great Lakes, a regional
advocacy group.
“Beaches are most peoples biggest, tightest connection to the Great
Lakes, so when beaches close, they really impact our quality of life in the
region.”
And ultimately, health is at stake too. For a long time, scientists tested
beach water for e coli because it’s associated with human feces. That is,
if e coli’s in the water, there’s a good chance sewage is there too, and
sewage can carry dangerous organisms – stuff that can cause hepatitis,
gastric diseases, and rashes.
Sewage can get into the Great Lakes after heavy rains. That’s because
some sewers and drains can’t keep up with the flow, and waste heads to
the lakes.
For a long time, scientists thought human feces was the only source of e
coli in Great Lakes water, but a puzzling phenomenon has them looking
for other causes, too. Experts say cities have been dumping less sewage
into the Great Lakes in recent years, but we’re seeing more e coli and
more beach closings.
Paul Bertram is a scientist with the U.S. Environmental Protection
Agency. He says, we’re closing more beaches because we’re testing
them more often.
“But I don’t think it’s because the Great Lakes are getting more polluted,
and more filled with pathogens, I think we’re just looking for it more.”
If we’re finding more e coli because we’re testing more often, we still
have a problem. We still need to know where the e coli’s coming from.
Bertram says there might be another culprit besides sewage.
“There is some evidence that it may in fact be coming from birds, flocks
of seagulls, things like that.”
But some researchers doubt sewage and bird droppings can account for
high e coli levels.
(Sound of research team)
A few researchers are sorting vials of water in a lab at the Lake Michigan
Ecological Research Station in Indiana.
Richard Whitman leads this research team. He says, in the past,
scientists could predict beach closings by looking out for certain events.
For example, they would take note of sewer overflows after heavy rains.
Whitman says researchers can’t rely on those triggers anymore.
“A large number, maybe even a majority of closures remain unexplained.
Today, we have closures and there’s no rainfall, may not even be
gulls, and we don’t know why the bacteria levels are high.”
Whitman has a hunch that e coli can grow in the wild, and doesn’t
always need human feces to thrive.
“This is my theory. E coli was here before we were. It has an ecology of
its own that we need understand and recognize.”
The idea’s pretty controversial. It runs against the prevailing theory that
e coli only grows in waste from warm-blooded animals, such as human
beings and gulls, but the idea’s also a kind of political bombshell.
If he’s right, it would mean our tests for e coli aren’t very accurate – they
don’t tell us whether there’s sewage around. After all, if e coli is nearly
everywhere, how can we assume it’s a sign of sewage?
“As a pollution indicator, you don’t want it to multiply. If it’s got an
ecology of its own, multiplying on its own, doing its own thing, then it’s
not a very good indicator.”
Whitman wants us to try other kinds of tests to find sewage. One idea is
to look for caffeine in the water. Caffeine’s definitely in sewage but it’s
not found naturally in the Great Lakes, but until we change our water
tests, Whitman will continue his work. He says we still need to know
how much e coli’s in nature and how much is there because of us.
Environmentalists want the government to keep a close watch on the new
science. They say we can’t let questions about the relationship between
e coli and sewage stop our effort to keep sewage and other waste out of
the Great Lakes.
Diporeia are disappearing from Lakes Michigan, Huron, Erie, and Ontario. The actual size of a diporeia is ½ an inch. (Courtesy of the EPA)
Some of the life in the Great Lakes has been hit hard by industry and trade. Pollution and
invasive species have hurt some of the native plants and animals important to the food
chain. While popular game fish might be the first to come to mind, it’s a little organism
at the bottom of the food chain that has biologists and fishing experts most concerned.
The Great Lakes Radio Consortium’s Lester Graham reports:
Transcript
In a survey, experts said one of the Ten Threats to the Great Lakes is a disappearing
species. Some native fish populations and organisms are declining. Our guide through
the Ten Threats series is Lester Graham.
Some of the life in the Great Lakes has been hit hard by industry and trade. Pollution and
invasive species have hurt some of the native plants and animals important to the food
chain. While popular game fish might be the first to come to mind, it’s a little organism
at the bottom of the food chain that has biologists and fishing experts most concerned.
The Great Lakes Radio Consortium’s Lester Graham reports:
(Sound of swinging doors)
Jack Donlan is taking me behind the fish counter at Donlan’s Fish House. In the
backroom he’s scaling and filleting some whitefish.
“Of the fishes caught in the Great Lakes, whitefish is one of the big volume fishes. Lake
perch, walleye bring more money per pound, but I would think from a tonnage-wise,
whitefish, it’s an extremely popular fish.”
This is a popular place to get Great Lakes fish, but Donlan’s suppliers, the commercial
fishers, are worried about the catch. At some places in the Great Lakes whitefish aren’t
doing too well.
(Sound of Lake Guardian motors)
Tom Nalepa is trying to figure out why whitefish are struggling. He’s onboard the U.S.
Environmental Protection Agency research ship, the Lake Guardian. Nalepa is a
biologist with the National Oceanic and Atmospheric Administration’s Great Lakes
Environmental Research Lab. He’s been studying Lakes Michigan and Huron, and on
this day he’s getting ready to study the bottom of Lake Erie.
He’s not studying whitefish. He’s actually looking for a tiny shrimp-like crustacean, only an
eighth to a quarter inch long, called diporeia. Eighty-percent of the whitefish diet is
made up of diporeia.
“And what we’re seeing is a dramatic drop in populations, and not only drops, but there are
large areas now in all the lakes, except Lake Superior, that no longer have diporeia. This
is real concern because diporeia is a very important fish food.”
Researchers used to find eight to 10-thousand diporeia or more in a square meter of sediment just
a few years ago. Now, there are only a dozen or so, or none at all. Diporeia is one of the
mainstays of the bottom of the food chain, and Nalepa says whitefish aren’t the only ones
that eat the tiny critters in the sediment at the bottom of the lakes.
“Just about every type of species found in the Great Lakes will feed on diporeia at some
stage in its life-cycle. Diporeia is high in calories and has a high-energy content. It’s a
very good food, nutritious food source for fish.”
Without it, fish are not getting enough to eat. Marc Gaden is with the Great Lakes
Fishery Commission. He says when diporeia disappears, commercial fishers can’t help
but notice.
“Right now we’re seeing skinnier whitefish. Whitefish that are somewhat emaciated in
some areas because they just don’t have as much of these low-end of the food web organisms
to eat, and we think it’s related to an invasive species that came in.”
That invasive species is the zebra mussel, and more recently another invader that was
likely carried to the lakes in the ballasts of ocean-going cargo ships, the quagga mussels.
Back on the Lake Guardian, Tom Nalepa says he’s seen the connection again and again.
“There’s no question that it’s related to zebra mussels and quagga mussels. In every area
that we’ve studied, regardless of the lake area, declines were happening a couple of years
after the quagga mussel or zebra mussel were first found, but that connection remains
elusive.”
Biologists thought the invasive mussels might have been filtering out all of the food the
diporeia eat, but when they find diporeia, they don’t appear to be starving. They appear
healthy. Now, scientists are wondering if there’s some kind of disease or toxin spread
by the mussels that’s wiping out the diporeia.
Even if researchers learn why the diporeia are disappearing, there might be nothing that
can be done to help. Some scientists worry that the decline of diporeia and other
organisms at the base of the food chain might ultimately lead to a massive collapse of fish
stocks in the Great Lakes.
Several state agencies in the region will
reduce the amount of salmon stocked in Lakes Huron and Michigan next year. The change is designed to help the alewife population recover. Alewives are the salmon’s main food source, but as the Great Lakes Radio Consortium’s Peter Payette reports, some biologists think helping the alewife will hurt native fish:
Transcript
Several state agencies in the region (IL, IN, MI, WI) will reduce the amount
of salmon stocked in Lakes Huron and Michigan next year. The change is
designed to help the alewife population recover. Alewives are the salmon’s
main food source, but as the Great Lakes Radio Consortium’s Peter Payette
reports some biologists think helping the alewife will hurt native fish:
The total number of salmon stocked in the two lakes will be cut by more than
a third next year. The state agencies that manage the stocking programs say
there was widespread support for the decisions, but one dissenting voice was
the Chippewa Ottawa Resource Authority, or CORA.
CORA supports recovery of native fish species like the Lake trout. Mark
Ebener is a fishery Biologist with CORA. He says you can’t protect
alewives and expect lake trout to do well.
“So you have to commit to one or the other. Instead of what the states are
going to do, and what Michigan is going to do, it’s going to protect alewife
by reducing stocking so they can have healthier salmon, but at the same time
it’s going to say, ‘Well tribes we still want you to support Lake trout
rehabilitation and we still support it and think it’s still feasible.'”
Female lake trout that have a diet heavy in alewives can develop a nutrient
deficiency. It causes most of their young to die soon after birth.
The Asian Carp is a big eater… and it’s moving closer to
the Great Lakes. Great Lakes states are hoping to stop the carp with electric barriers on the Chicago Ship and Sanitary Canal. But as the Great Lakes Radio Consortium’s Rebecca Williams reports… a Congressional committee voted against operating money for the barriers:
Transcript
The Asian Carp is a big eater, and it’s moving closer to the Great Lakes.
Great Lakes states are hoping to stop the carp with electric barriers on the
Chicago Ship and Sanitary Canal, but as the Great Lakes Radio Consortium’s
Rebecca Williams reports a Congressional committee voted against operating
money for the barriers:
It’s estimated the Asian Carp is about 20 miles away from Lake Michigan.
Right now there’s a temporary electric barrier standing in its way, and the
Army Corps of Engineers is building a second, stronger barrier. Great Lakes
states are looking to Congress for money to operate the carp barriers, but a House-Senate
conference committee recently voted against any funding for them. Without federal funding the
state of Illinois will have to come up with the hundreds of thousands of dollars to operate and
maintain the barriers.
Marc Gaden is with the Great Lakes Fishery Commission.
“We think that this is actually a national problem. The carp escaped from the
southern United States and have been making their way northward and have been causing
destruction on their whole path, so this is something that’s more than just
a Great Lakes or even a state of Illinois issue.”
Gaden says two additional bills before Congress could provide money to
operate the barriers, but he says the carp might move faster than either of
those bills.
These fishermen at Port Clinton, Ohio, are a few miles away from the dead zone that develops in Lake Erie every summer... so far, most fish can swim away from the dead zone. But the dead zone is affecting the things that live at the bottom of the lake. (Photo by Lester Graham)
One of the Ten Threats to the Great Lakes is nonpoint source pollution. That’s pollution that
doesn’t come from the end of a pipe. It’s oil washed off parking lots by storms, or pesticides and
fertilizers washed from farm fields. Nonpoint source pollution might be part of the reason why
some shallow areas in the Great Lakes are afflicted by so-called dead zones every summer.
Transcript
In another report on the Ten Threats to the Great Lakes series, reporter Lester Graham looks at a
growing problem that has scientists baffled:
One of the Ten Threats to the Great Lakes is nonpoint source pollution. That’s pollution that
doesn’t come from the end of a pipe. It’s oil washed off parking lots by storms, or pesticides and
fertilizers washed from farm fields. Nonpoint source pollution might be part of the reason why
some shallow areas in the Great Lakes are afflicted by so-called dead zones every summer.
Dead zones are places where there’s little or no oxygen. A dead zone develops in Lake Erie
almost every summer. It was once thought that the problem was mostly solved. But, it’s become
worse in recent years.
(sound of moorings creaking)
The Environmental Protection Agency’s research ship, the Lake Guardian, is tied up at a dock at
the Port of Cleveland. Nathan Hawley and his crew are loading gear, getting ready for a five day
cruise to check some equipment that measures a dead zone along the central basin of Lake Erie.
“What I have out here is a series of bottom-resting moorings that are collecting time series data of
currents and water temperature and periodically we have to come out here and clean them off and
we take that opportunity to dump the data as well.”
Hawley is gathering the data for scientists at several universities and the National Oceanic and
Atmospheric Administration’s Great Lakes Environmental Research Lab. The information helps
them measure the behavior of the dead zone that occurs nearly every year in Lake Erie…
“What we’re trying to do this year is get a more comprehensive picture of how big this low-oxygen zone is and how it changes with time over the year.”
One of the scientists who’ll be pouring over the data is Brian Eadie. He’s a senior scientist with
NOAA’s Great Lakes Environmental Research Lab. He says Lake Erie’s dead zone is a place
where most life can’t survive…
“We’re talking about near the bottom where all or most of the oxygen has been consumed so
there’s nothing for animals to breathe down there, fish or smaller animals.”
Lester Graham: “So, those things that can swim out of the way, do and those that can’t…”
Brian Eadie: “Die.”
The dead zone has been around since at least the 1930’s. It got really bad when there was a huge
increase in the amount of nutrients entering the lake. Some of the nutrients came from sewage,
some from farm fertilizers and some from detergents. The nutrients, chiefly phosphorous, fed an
explosion in algae growth. The algae died, dropped to the bottom of the lake and rotted. That
process robbed the bottom of oxygen. Meanwhile, as spring and summer warmed the surface of
Lake Erie, a thermal barrier was created that trapped the oxygen-depleted water on the bottom.
After clean water laws were passed, sewage treatment plants were built, phosphorous was banned
from most detergents, and better methods to remove phosphorous from industrial applications
were put in place.
Phosphorous was reduced to a third of what it had been. But Brian Eadie says since then
something has changed.
“The concentration of nutrients in the central basin the last few years has actually been going up.
We don’t understand why that’s happening.”
Eadie says there are some theories. Wastewater from sewage plants might be meeting pollution
restrictions, but as cities and suburbs grow, there’s just a lot more of it getting discharged. More
volume means more phosphorous.
It could be that tributaries that are watersheds for farmland are seeing increased phosphorous. Or
it could be that the invasive species, zebra mussel, has dramatically altered the ecology of the
lakes. More nutrients might be getting trapped at the bottom, feeding bacteria that use up oxygen
instead of the nutrients getting taken up into the food chain.
Whatever is happening, environmentalists are hopeful that the scientists figure it out soon.
Andy Buchsbaum heads up the Great Lakes office of the National Wildlife Federation. He says
the dead zone in the bottom of the lake affects the entire lake’s productivity.
“If you’re removing the oxygen there, for whatever reason, for any period of time, you’ve
completely thrown that whole system out of balance. It’s all out of whack. It could mean
irreversible and devastating change to the entire ecosystem.”
And Buchsbaum says the central basin of Lake Erie is not the only place where we’re seeing this
low-oxygen problem…
“What makes the dead zone in Lake Erie even more alarming is that we’re seeing similar dead
zones appearing in Saginaw Bay which is on Lake Huron and Green Bay in Lake Michigan.
There, too, scientists don’t know what’s causing the problem. But, they’re already seeing
potentially catastrophic effects on aquatic life there.”
State and federal agencies and several universities are looking at the Lake Erie dead zone to try to
figure out what’s going on there. Once they do… then the battle likely will be getting
government to do what’s necessary to fix the problem.
Because alewives are the main source of food for some sport fish, some people forget that they're an invasive species. (Photo courtesy of NOAA Fishery Service)
As we look at the “Ten Threats to the Great Lakes,” we’re spending some time examining the effects of the alien invasive species that have changed the Lakes. One of the first invasive species to arrive in the Great Lakes was the alewife; it’s native to the Atlantic Ocean. It has become the most beloved of all the invasives. That’s because it’s food for the most popular sport fish in the Great Lakes. But in the beginning, the sport fish was introduced to get rid of the alewives. Peter Payette reports:
Transcript
Today we’re continuing our series on Ten Threats to the Great Lakes. The Great Lakes Radio Consortium’s Lester Graham is our series guide:
As we look at the “Ten Threats to the Great Lakes,” we’re spending some time examining the effects of the alien invasive species that have changed the Lakes. One of the first invasive species to arrive in the Great Lakes was the alewife; it’s native to the Atlantic Ocean. It has become the most beloved of all the invasives. That’s because it’s food for the most popular sport fish in the Great Lakes. But in the beginning, the sport fish was introduced to get rid of the alewives. Peter Payette reports:
When autumn arrives in Northern Michigan, salmon fishermen line the rivers. The fish, native to the Pacific Ocean, swim upstream to spawn and then die. That’s why Tim Gloshen says they’re not interested in his bait.
“But if you irritate ’em enough and keep putting it in front of them, they’ll snap at it sometimes and you got to be ready when they hit it and set your hook.”
Anglers caught eight million pounds of salmon in Lake Michigan last year. Most of the fish are caught out in the lake.
“I got buddies that are catching couple hundred a year out there. They’re out there twice a week at least, all summer long, you know.”
Tim and his buddies and everyone else who fishes for salmon in the Great Lakes are at the top of the food chain. The money they spend on food, lodging, tackle, and boats figures heavily into decisions about how to manage the Lakes.
But it wasn’t always so.
Pacific salmon were stocked here about forty years ago to control the invading alewives. The native lake trout had just about been wiped out by overfishing and the sea lamprey. With no big predators left, the alewife population exploded.
At one point, it was estimated that for every ten pounds of fish in Lake Michigan, eight were alewives. Occasional die-offs would cause large numbers of alewives to wash up on beaches all over the Great Lakes. Historian Michael Chiarappa says all this was happening as America was feeling the urge to get back in touch with nature.
“And that’s when you get this rise in greater interest in sport fishing, recreational fishing, hunting. Teddy Roosevelt sort of epitomized the spirit of the strenuous life; get back out there and engage nature. It’s good for the soul, it’s good for the body, it’s good for the mind.”
So the salmon was brought in to control the alewife population and transform the Great Lakes into a sport fishing paradise. And it worked. But alewives remained the best food source for the ravenous salmon.
So now a healthy alewife population is seen as a good thing by the states that benefit economically from the recreational fishing. Mark Holey, with the U.S. Fish and Wildlife Service says this has caused people to forget alewives are an invasive species.
“If alewives were knocking on the door today, there may be a much different discussion about it. It may be more like the Asian carp.”
How the alewife would compare to Asian carp is unknown, because the Asian carp has been found in the Mississippi River, but not yet in the Great Lakes. What is known is that when alewives are abundant, native fish don’t do well. For example, Holey says biologists used to think PCBs caused many young lake trout to die. Now they know early mortality is mostly due to thiamin deficiency.
Thiamine is a vitamin lacking in lake trout that eat too many alewives.
“From the studies that we’ve been involved with, anywhere, right now, anywhere between thirty to fifty percent of the females that we take eggs from show some… their eggs show some signs of thiamine deficiency. Which means survival of those eggs are impaired.”
In some cases, none of the eggs will survive. So a worse case estimate would be half of the wild lake trout in the Great Lakes can’t reproduce because of alewives. This is why advocates for native fish species have been happy to see the alewife populations decline in recent years. They almost disappeared from Lake Huron.
Mark Ebener is a fisheries biologist for the Chippewa Ottawa Resource Authority. He says the government agencies that stock salmon and lake trout should stock more than ever to keep pressure on the alewife. Ebener thinks with alewife numbers down, there’s an opportunity to reestablish the native herring as the main prey fish in the Lakes, especially in Lake Huron.
“Saginaw Bay used to have a huge population of lake herring that’s essentially gone. They used to have a tremendous commercial fishery for it, and people used to come from miles around to buy herring there, and everybody in the lower end of the state used to have herring come fall and the springtime when the fishers were fishing, but they’re gone.”
This opportunity to bring herring back might not last much longer. The warm weather this past summer will probably help alewives rebound next year.
