Tag: alewives

Invasive Die-Off Stirs Fishery Debate

  • A naturally reproduced wild lake trout fingerling. (Photo courtesy of MI DNR.)

The fisheries in the Great Lakes are seeing dramatic changes. In one lake, an invasive species that has become part of the food chain has collapsed. But some native fish are doing better because of that collapse. Lester Graham reports some fishery managers are debating what to do next:

Transcript

The fisheries in the Great Lakes are seeing dramatic changes. In one lake, an invasive species that has become part of the food chain has collapsed. But, some native fish are doing better because of that collapse. Lester Graham reports some fishery managers are debating what to do next:


When we started digging canals, connecting the lakes to the Atlantic Ocean, things changed a lot for the fish in the Great Lakes.


First, the sea lamprey got into the lakes through the Welland canal that bypasses Niagara Falls.


The lamprey is an eel-like parasite that nearly wiped out the big fish in the Great Lakes by attaching to them and sucking the life out of them.

Also slipping through the canals was a smaller fish, the alewife. Since the lamprey wiped out most of the predator fish in the lakes, the alewife population exploded. They out-competed native fish for food. It got so bad, that by the mid 1960s, if you weighed all the fish in Lake Michigan, more than 80% of the weight would have been alewives.


So, once wildlife managers got the sea lamprey under control, they had to figure out what they could do to get alewives under control. The fish biologists decided to introduce new predators, trout and salmon, to prey on the alewives. These fish were not native to the Great Lakes. Expensive nurseries were built by federal and state game agencies to keep supplying new trout and salmon every year to prey on alewives.


Forty years later, in Lake Huron, the alewife population collapsed, and in Lake Michigan alewives are declining rapidly. Mission accomplished, right?


Well, in that 40 years, a whole recreational fishing industry has grown up around fishing for those introduced trout and salmon. Some fishery managers now say we have to find a balance of the right amount of alewives to sustain the introduced trout and salmon fishery. So, recently states have cut their trout and salmon stocking programs to give alewives a chance to recover.


Tom Trudeau [who] operates a fish nursery for the state of Illinois says it would cause trouble to try to take the Great Lakes back to native fish only.


“We do have this industry that we have pressure to keep. You know, you’re putting a lot of people out of business if you get rid of it.”


And Trudeau says because of ecological damage, many of the smaller native fish on which big predators used to feed have been wiped out.


“So, I mean, of the six or seven species in that category, we only have one. And a couple of them are extinct. So, I mean, we could talk about going back to the ideal situation of pure native species, but we’ve disrupted the habitat so much.”


So, the argument goes, the invasive alewives are now needed. But something unexpected happened when the alewives disappeared from Lake Huron. The native fish, walleye, yellow perch, and lake trout started doing better.


Dave Fielder is a fisheries research biologist with the Michigan Department of Natural Resources.


“We’ve long known that adult alewives were a predator and a competitor on newly hatched perch and walleye fry. We just didn’t realize how substantial that effect was until finally the adult alewives were removed from the system and now we’re enjoying some greatly increased reproductive success. Walleye, particularly in Saginaw bay, are at some of the highest levels that we’ve seen in a long time.”


But, after 40 years, people are used to fishing for those introduced trout and salmon. And some fisheries managers are wondering what will happen to all those expensive nurseries that provide their jobs.


What happens to all of those charter boat fishing operations, fishing tourism, if the government were to stop stocking those trout and salmon? Would they switch to fishing for native fish? And, can the native fish even survive in the long-run since so many of the smaller native prey-fish are no longer around?


Dave Fielder says it’s hard to say.


“So, we’re kind of in the middle of a change – it’s really a paradigm shift in many ways – and that’s always scary because nobody really knows how we’re going to end up, but I prefer to be optimistic. I think there are a lot of reasons to be hopeful in regards to the benefits that we’re seeing for our native species.”


But some fisheries managers say the debate of whether to go all native or to try to find the right mix of native and non-native fish is not over. Since invasive species, pollution, and habitat destruction have changed the Great Lakes so much, wildlife managers think they’ll still have to keep stocking one kind of fish or another to keep the recreational fishing industry going. If that’s the case, does it matter whether it’s native fish, or the introduced fish that anglers have grown to like so much?


For the Environment Report, this is Lester Graham.

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Yellow Perch Making Resurgence?

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.


For the GLRC, I’m Peter Payette.

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Salmon Stocking Cuts to Hurt Native Fish?

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.


For the GLRC, I’m Peter Payette.

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Ten Threats: The Beloved Invader

  • 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.


For the GLRC, I’m Peter Payette.

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Alewife Die-Off Sparks Worries for Salmon

  • Because alewives make up a large portion of salmon diets, alewife die-offs are causing concerns that salmon populations might also decline. (Photo courtesy of the Fish and Wildlife Service)

A small fish is dying off in parts of the Great Lakes. According to the U.S. Geological Survey, the amount of alewives in Lake Michigan dropped nearly 70 percent last year. And biologists say the decrease might signal trouble for the salmon fishery. The Great Lakes Radio Consortium’s Peter Payette reports:

Transcript

A small fish is dying off in parts of the Great Lakes. According to the U-S
Geological Survey, the amount of alewives in Lake Michigan dropped nearly 70
percent last year. And biologists say the decrease might signal trouble for
the salmon fishery. The Great Lakes Radio Consortium’s Peter Payette
Reports:


Lake Michigan’s alewife population has been lower than it is now a few times
in the last 20 years. But Lake Huron’s alewife population is practically zero.


That’s why salmon in Huron are small and many are coming over to Lake
Michigan to feed.


USGS Biologist Charles Madenjian says the problem is stocked salmon are now
reproducing naturally.


And the growing numbers of salmon are eating up all the alewives.


“People fear that if alewives stay at this low level, the salmon are more
prone to disease and you’ll get a die-off.”


Neither salmon nor alewives are native to the Great Lakes.


Alewives swam in from the Atlantic Ocean through the Welland Canal. Salmon were introduced in part to control the alewife population.


For the GLRC, I’m Peter Payette in Traverse City.

Related Links

Controlling the Lamprey

The assault against sea lampreys in the Great Lakes continues, as biologists from the U.S. Fish and Wildlife Service are combing the waters of West Michigan’s Lincoln and Pere Marquette rivers this week. The Great Lakes Radio Consortium’s Matt Shafer Powell has more on the government’s on-going attempts to keep this creature under control:

The Business of Fish Management

  • Similar scenes can be found up and down the eastern shore of Lake Michigan.

Now that summer’s officially here, beaches around the region are packed with
tourists and locals. But this year many beaches have been plagued with
unwanted visitors: tens of thousands of dead fish in the water and on the
sand. It’s a revolting sight-and smell – but in fact, the fish play an
important role in the lakes…and present an ongoing management challenge to
biologists. The Great Lakes Radio Consortium’s Wendy Nelson explains: