Multimillion Dollar Parasite Fight Continues

  • A sea lamprey, the first invasive species in the Great Lakes. (Photo courtesy of the USEPA)

One of the most destructive invasive species in the Great Lakes was also the first one to arrive. The sea lamprey invaded the Lakes more than a hundred years ago, and no one’s been able to get rid of it. As Rebecca Williams reports, it’s the only invader in the Lakes that managers have been able to control… but it takes millions of taxpayers’ dollars every year to keep the blood-sucking parasite in check, and there’s no end in sight:

Transcript

One of the most destructive invasive species in the Great Lakes was also the first one to arrive. The sea lamprey invaded the Lakes more than a hundred years ago, and no one’s been able to get rid of it. As Rebecca Williams reports, it’s the only invader in the Lakes that managers have been able to control… but it takes millions of taxpayers’ dollars every year to keep the blood-sucking parasite in check, and there’s no end in sight:

(Sounds of tank bubbling)


There’s a sea lamprey sucking on Marc Gaden’s hand.


“You can see he’s really got my thumb now, I’ll try and pull him off my thumb – this is a suction cup (popping sound of lamprey being detached).”


Gaden is with the Great Lakes Fishery Commission. It’s a group that was created by the US and Canadian governments with one main purpose: to control the sea lamprey. Gaden isn’t in any actual danger when a lamprey’s hanging on him. They don’t feed on warm-blooded creatures. But fish are another story.


“The mouth is ringed with sharp teeth, row after row of these sharp teeth, and in the middle of the mouth there is a tongue that flicks out and it’s sharp as a razor. What that tongue does is files its way through the side of the fish’s scales and skin and then the sea lamprey has access to blood and body fluids of the fish and that’s what it does, it feeds on them.”


Sea lamprey get fat drinking fish blood and fluids. They leave bloody holes in the side of fish, wounds that often kill the fish. Each lamprey can kill 40 pounds of fish a year.


Lamprey got into the lakes through manmade canals that connected to the Atlantic Ocean. By the 1940’s, the exotic species had invaded every one of the Great Lakes. Marc Gaden says by the 1950’s, lampreys had killed off most of the big predator fish in the Lakes.


“There’s literature around that time period that talked about gaping bloody wounds that commercial fishermen were finding on their catch, the commercial catch was beginning to go down the tubes, also because of overfishing, but sea lamprey was a major cause of that decline.”


Paul Jensen’s family used to fish for the popular lake trout before the lamprey wiped them out. Jensen now fishes for whitefish. He’s one of a small pool of commercial fishers who still pull a living from the Lakes.


“Every port along southern Michigan had commercial fishermen. South Haven, St. Joseph, Ludington, Manistee… There aren’t any, they’re gone. And one of the main reasons they’re gone, I think can be traced back to sea lamprey.”


Jensen says most commercial fishers these days have to do more than catch fish. He also runs a marina and builds research boats. Jensen says commercial fishers either had to adapt to the changes the lampreys brought or get out of the business.


“The whole food chain has just been devastated and turned upside down by exotics, and it’s been kind of a mystery; we have no clue as to where it’s gonna go. We’re glad with what we’re getting but I don’t know if we have much control of where it’s going.”


The people who manage fisheries have been wrestling for control over the sea lamprey. Marc Gaden says the lamprey control program has reduced the parasites’ numbers by 90 percent over the past 50 years. But he says lampreys have recently rebounded above target levels in several areas of the Great Lakes.


“It goes to show you these are crafty beasts. Even though they’re primitive and haven’t evolved much since the time of the dinosaurs, they still will find ways in which to spread and find new stream habitats and we always have to try our best to stay one step ahead of them.”


Gaden says the fishery commission has been aggressively treating the areas where lamprey numbers are too high. The main method is a lampricide that kills lamprey when they spawn in streams. Researchers are also working on chemical attractants to lure lampreys into traps.


But all of this takes money. Since the 1950’s, the US and Canada have spent about $300 million to keep lampreys in check. Marc Gaden says that sounds like a lot of money, until you look at the value of the fishery. It’s valued at about 4 billion dollars a year.


“So the amount of money we spend, upwards of 20 million a year, to keep lampreys under control, is a tiny fraction of the value of that fishery. But nevertheless it’s a cost we’re going to have to endure in perpetuity because the lampreys are not going away.”


But the Bush Administration’s proposed budget cut some of the funding for lamprey control. The fishery commission is hopeful that Congress will restore the funding. Marc Gaden says if we want any sport fishing, any tribal fishing, any commercial fishing… lampreys have to be kept under control, and that takes steady funding from Congress.


For the Environment Report, I’m Rebecca Williams.

Related Links

Multimillion Dollar Parasite Fight Continues (Spot)

The sea lamprey invaded the Great Lakes more than a hundred years ago, and no one’s been able to get rid of it. But Rebecca Williams reports it’s the only invader in the Lakes that managers have been able to control. Experts say it can only be kept in check if Congress continues to provide funding each year:

Transcript

The sea lamprey invaded the Great Lakes more than a hundred years ago, and no one’s been able to get rid of it. But Rebecca Williams reports it’s the only invader in the Lakes that managers have been able to control. Experts say it can only be kept in check if Congress continues to provide funding each year:


The sea lamprey got into the Great Lakes through a manmade canal. The parasite attaches itself to fish and sucks out the blood and body fluids.
By the 1950’s, sea lampreys knocked out the big predator fish in the Lakes.


A few years later, biologists discovered a pesticide that kills lampreys. That pesticide is the major tool managers still use today to keep lamprey numbers down.


Marc Gaden is with the Great Lakes Fishery Commission. The commission’s in charge of controlling the lampreys. He says in order to have healthy fish populations, lampreys have to be kept in check.


“It’s like a coiled spring, as long as you have your thumb on it, everything’s fine but the moment you take it away it’ll just spring out of control, bounce back right to where it was before.”


The Bush Administration’s proposed budget cut some of the funding for the lamprey program. But the fishery commission is hopeful Congress will restore the funding.


For the Environment Report, I’m Rebecca Williams.

Related Links

Native Lake Species Fighting Back

  • Alewives washed up on Lake Michigan shores after the invaders' populations exploded, then crashed. Researchers have a difficult time predicting how invasive species will affect the balance of nature in the Great Lakes.

Ever since the Great Lakes were opened to shipping, exotic species of aquatic animals have invaded the lakes. Nearly always it’s been bad news for the region’s native fish and wildlife. The Great Lakes Radio Consortium’s Lester Graham reports on the latest effects of the invaders:

Transcript

Ever since the Great Lakes were opened to shipping, exotic species of aquatic animals have invaded the lakes. Nearly always it’s been bad news for the region’s native fish and wildlife. The Great Lakes Radio Consortium’s Lester Graham reports on the latest effects of the invaders.


Some of the exotic species that have caused major problems in the Great
Lakes have been around since the 1940’s and ’50s. For example, the sea lamprey found its way into the lakes through manmade channels. It’s a parasite that attacks lake trout and other large game fish. It devastated the lake trout fisheries. Only recently have efforts gotten the lamprey under control. It’s still out there, but it’s not decimating the lake trout population as it once was.


More recently, a big concern has been the zebra mussel. It hitchhiked its way to the Great Lakes in the ballast water of cargo ships. In the last couple of decades the zebra mussel has caused major changes in all the lakes except for Superior where it seems limited to the shallow and warmer bays.


David Jude is a researcher with the University of Michigan’s Center for
Great Lakes and Aquatic Sciences. He says the huge numbers of zebra mussels siphon through lake water like a giant network of filters. There are so many of them that water in the lakes is actually clearer.


“I think people tend to hear about the water clarity increases. ‘Ah, the water’s clearer,’ you know, ‘That’s great!’ But it’s not great, because there’s a lot of things going on in the water column.”


Things such as, algae converting the sun’s energy into more phytoplankton.
Small fish and tiny invertebrate animals called zooplankton eat the phytoplankton and then they become food for fish. But, the zebra mussels filter out a lot of the phytoplankton, stealing food from the native zooplankton.


David Jude says a couple of other invaders are also causing havoc at the base of the food chain in the Great Lakes. Instead of eating just the green phytoplankton, zooplankton invaders from the Black and Caspian Seas also eat their North American cousins.


“These are predators. And they feed on the zooplankton, our native zooplankton that is out there already. So, not only do we have the impact of zebra mussels removing algae which is a food for these zooplankton, now we’ve got two predators that have been introduced and both of those will eat zooplankton which would have been food for fish to eat.”


Besides the zooplankton floating around in the water column, a major food source for fish is in the sediment at the bottom of the lakes, and it’s disappearing. James Kitchell is with the University of Wisconsin – Madison. He says many different kinds of fish depend on a little creature called diaporeia, which have become scarce in many areas.


“It appears to correlate in general with an increases in zebra mussels. So, there’s the prospect that diaporeia is literally starving to death as a consequence of zebra mussels eating the available food, but when you look at the diaporeia, they appear to be healthy. They’re not skinny and look to be starving. So that doesn’t explain it.”


It’s a big concern because a lot of fish that anglers like, such as yellow perch, depend on diaporeia for food.


Besides the zebra mussels and the two zooplankton predators, a fourth invader is causing problems. Populations of the round goby, an ugly, aggressive feeding little fish from Eastern Europe, have exploded in the Great Lakes. The round goby scours the bottom, eating the eggs and larvae of native fish. The University of Michigan’s David Jude says as big of a problem as the invasive fish has been over the last several years. The round goby’s future might soon be curtailed a bit.


“We did SCUBA dives in Lake Erie, for example, we’d turn over rocks. Round gobys would tear out from under the rocks and we’d have small mouth bass following us around and they would ignore the round gobys. They didn’t know how to catch a round goby. But, because there’s so many round gobys now, they had to learn how to eat them or die. So, the predators are definitely learning how to eat round gobys.”


Other native fish are beginning to eat the exotics. The silver chub, which once nearly disappeared from the Great Lakes, is making a bit of a comeback feasting on zebra mussels. With each invader, the lakes ecosystems go through upheaval, and then find a new balance. But make no mistake. It’s a different balance. Nicholas Mandrak is a researcher at Youngstown State University. He says exotic species invading the Great Lakes will mean continued changes, and for people who fish the lakes, not many of the changes will be good.


“You’re not going to be able to catch as many species that you’re used to catching. You know, the native species are going to decline. The walleye are going to decline. So, I think the bottom line is the recreational and commercial fisheries are going to change in a manner that is negative to most people.”


Researchers, though, have learned to be careful about predicting how invasive species will affect the lakes. They’re often surprised by the intricacies of the food web and the ecosystems that support it. Throwing an exotic invader into the mix makes it that much more unpredictable, and it will likely get worse. Mandrak says they’ve been studying how global warming might affect the lakes. One scenario suggests 30 to 40 new exotic species from the South will make their way through manmade canals as temperatures rise. For the biologists, it’s a worrisome concept. For the Great Lakes Radio Consortium, this is Lester Graham.

NATIVE LAKE SPECIES FIGHTING BACK (Short Version)

It appears that fish native to the Great Lakes are beginning to prey on some of the alien species that have invaded the lakes. The Great Lakes Radio Consortium’s Lester Graham reports:

Transcript

It appears that fish native to the Great Lakes are beginning to prey on some of the alien species that have invaded the lakes. The Great Lakes Radio Consortium’s Lester Graham reports.


Aquatic Species from Europe and elsewhere have hitchhiked to the Great Lakes in the ballasts of cargo ships for many years. A lot of them have upset the natural ecosystems of the lakes. Lately, though, some native fish are taking advantage of the invaders. Nicholas Mandrak is a researcher at Youngstown State University. He says a Great Lakes minnow that was once thought to have died out has recently re-emerged.


“And they’re eating zebra mussels. So, it looks like the increase
in silver chub is related to zebra mussels, so we finally found a native
fish that is benefiting from the zebra mussel.”


Other researchers say small mouth bass are beginning to prey on another invasive species, the round goby, which eats the eggs and larvae of fish native to the Great Lakes. The researchers say the benefits don’t outweigh the negative affects on native species. But it evens the score a little. For the Great Lakes Radio Consortium, this is Lester Graham.

Success in Controlling the Lamprey

  • Sea lampreys feed on a lake trout. The invasive species damages the Great Lakes fishery. (photo courtesy Great Lakes Fishery Commission)

A new effort to eradicate the sea lamprey is attacking one major
trouble spot. The Great Lakes Radio Consortium’s Lester Graham
reports… the parasite is being trapped and poisoned:

Related Links