Tag: zooplankton

Keeping a Big Fish From Butting In

  • Asian Carp can grow up to 110 pounds (Photo courtesy of the US Fish and Wildlife Service)

There are invasive fish swimming their
way toward the Great Lakes. If they get in,
they could swallow up a multi-billion dollar
sport fishing industry. Mark Brush reports,
officials are investing millions of dollars
to keep Asian Carp out of the Great Lakes:

Transcript

There are invasive fish swimming their
way toward the Great Lakes. If they get in,
they could swallow up a multi-billion dollar
sport fishing industry. Mark Brush reports,
officials are investing millions of dollars
to keep Asian Carp out of the Great Lakes:

Asian Carp were imported by fish farms in Mississippi and Arkansas to control algae.
But the fish escaped during floods. They swam out of the fish ponds, and into the Mississippi
river. And they’ve been moving north ever since.

(sound of boats)

Thad Cook is on a tributary of the Mississippi River in Illinois. This river is more than
400 miles upstream from where Asian Carp first escaped the fish farms.

Cook is looking
for two types of Asian Carp known as Silver and Bighead Carp. It turns out t’s not hard to find them. He dips an electrified pole into the water – and the fish jump right out of the
river and into the boat.

(sound of fish flopping in boat)

Cook is with the Illinois Natural History Survey. His group, along with several others,
has been making trips like this one for years. They’ve been keeping a close eye on where
the fish are going. He takes a guess at how big this fish is.

“No he’ll go… uh.. he’s probably…”

“Hold him out there Jimmy!”

“Yep, six, seven, eight, nine, ten pounds.” (Laughter)

His fish story could have gone a lot further. Some types of these Carp can get up to a
hundred pounds. There aren’t many fish that can compete with an appetite like that.

Biologists are finding that these carp are pushing native fish species aside as they spread
north through the Mississippi River system. And some fear it’s only a matter of time
before they swim their way into the Great Lakes.

David Jude is a fisheries biologist with the University of Michigan.

“I’m very concerned about what impact they would have in the Great Lakes because
they’re planktovores which means they filter zooplankton from the water column. And, they’re just huge fish. And so they have the potential for having
a tremendous impact on our ecosystems.”

He says the silver and bighead carps are filter feeders. They pass up eating smaller fish –
and head straight for the bottom of the food chain.

Jude says if Asian carp get in, it’ll make a bad situation worse. The Great Lakes are
already losing zooplankton from other invasive species. Asian Carp could
destroy a 4 billion dollar a year sport fishing industry.

(sound of canal)

And here is where the battle line is being drawn. The fish have been spotted thirty miles
downstream from this spot on the Chicago Ship and Sanitary Canal. A century ago,
engineers blasted through solid rock to connect the Great Lakes with the Mississippi
River system.

Chuck Shea is with the U.S. Army Corps of Engineers.

“Any type of fish that would want to move between Lake Michigan and the Mississippi
river basin – has to pass through the Chicago Sanitary and Ship Canal – there’s no other way to swim through. So, they have to come through this body of water we’re standing in front
of right now.”

Shea is in charge of the construction and maintenance of two electric fish barriers along this canal.
When this barrier is online, machines will pulse electricity into the water. The electric current shocks
the fish – making them swim away.

This barrier hasn’t been turned on yet. There have been delays due to funding shortages. And they’re still
doing safety testing with the Coast Guard.

Right now, the only thing that would keep the carp from getting into the Great Lakes is a temporary electric
barrier built six years ago.

The good news is that there still seems to be a little time. Biologists say, so far, Asian Carp haven’t moved any
closer than thirty miles from the barrier for the last couple of years.

For The Environment Report, I’m Mark Brush.

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Invasives Destroying Great Lakes Food Chain

  • Biologists sorting fish. The populations of smaller fish that game fish eat have collapsed in Lake Huron. (Photo courtesy of MI DNR)

Although zebra mussels have been affecting the ecology of the Great Lakes since they were first found in 1988, researchers are continuously surprised at how much damage they’ve caused. Now, biologists are wondering if zebra mussels and the more recently arrived quagga mussels are to blame for a collapse of the fishery in one of North America’s largest lakes. Lester Graham reports the researchers are also wondering if this collapse is a preview of what will happen to all of the Great Lakes:

Transcript

Although zebra mussels have been affecting the ecology of the Great Lakes since they were first found in 1988, researchers are continuously surprised at how much damage they’ve caused. Now, biologists are wondering if zebra mussels and the more recently arrived quagga mussels are to blame for a collapse of the fishery in one of North America’s largest lakes. Lester Graham reports the researchers are also wondering if this collapse is a preview of what will happen to all of the Great Lakes:


It’s off-season for charter boat fishing and Captain Wayne Banicky asked if we could meet at a local watering hole called the Boat Bar. Captain Banicky takes people out fishing on Lake Huron. Well, he used to. The past few years he’s been charter boat fishing in Lake Michigan. He says fish started to become more scarce on Lake Huron, and he was forced to make the move.


“Economics, pure and simple. Dollars and cents. Once you start seeing a decline and being on the water every day and you see those declines in your numbers, it’s just a matter of time before financially you can’t afford to stay there. Those dock fees aren’t given up free. That’s an expensive tab to pay every year.”


Fishing for most species in Lake Huron is not good. But the story is not just a matter of not stocking enough fish or just a bad year, it’s a matter of a collapse of the bottom of the food chain. It’s not just the fish sport fishers like to catch that are down, it’s their prey: the smaller fish those big game fish eat. Prey fish stocks have collapsed, and supplies of the food those small prey fish eat, the plankton, have also collapsed.


Jim Johnson is with the Michigan Department of Natural Resources Alpena Fisheries Research Station.


“There was a huge decline in the amount of nutrients available to zooplankton and phytoplankton in the middle of Lake Huron. These are the basic nutrient bits that fish eat. And it appears now to most of us in the scientific community that a large portion of the nutrients that used enter Lake Huron are now being trapped by zebra and quagga mussels and not finding their way to alewives and other prey fish.”


Scientists from different government agencies and universities in the U.S. and Canada had been noticing changes, but things have gone seriously wrong very quickly in Lake Huron, and it might go wrong other places.


Tom Nalepa is with the National Oceanic and Atmospheric Administration’s Great Lakes Environmental Research Lab. He says tiny aquatic food sources for fish, such as a shrimp-like organism called diporeia, are declining dramatically in other Great Lakes.


“All the players are in place for it to happen in these other lakes too, you know, the loss of diporeia, the expansion of quagga mussels. And maybe Lake Huron is the first to show a collapse in the prey fish. What does it mean? Well basically, you know, there’s not going to be many fish out there for the sport fisherman to catch anymore.”


And sport fishing is multi-billion dollar industry in the Great Lakes. Back at the Boat Bar, charter fishing boat captain Wayne Banicky says fishing is still good in Lake Michigan, but he worries when he thinks about what happened in Lake Huron.


“I think that the fishery as a whole in the Great Lakes is in serious jeopardy right now. Something’s got to be done.”


But the question is what? What can be done when invasive species are changing an entire ecosystem to the point the fishery collapses?


“I don’t know to be honest with you. I don’t think any one of us knows. It’s scary, that much I will admit to you. It is scary right now.”


And guys like Captain Banicky aren’t the only ones worried.


Jim Johnson at Alpena Fisheries Research Station says you can’t undo the damage that’s already done. It’s just a matter of waiting to see how nature responds to the invasive zebra and quagga mussels and other invaders. Johnson says the key is to prevent more invasive species from being introduced to the lakes.


“The best we can do right now, I think the single most effective thing we as managers can do, is to make it understood by the decision makers just how disruptive the invasive species are and try to put a stop to those.”


The source of many of these invasive species is the ballast tanks of foreign ships entering the Great Lakes. Some regulations have reduced the chance that more invasive species will hitchhike to the Great Lakes, but more are still getting in. In the meantime, agencies such as the US Environmental Protection Agency and the US Coast Guard say Congress hasn’t given them the authority to regulate foreign ships strictly enough to stop new invasive species from entering.


So, fishery managers can only watch the other Great Lakes for more signs of a collapse of the fisheries as they’ve only been able to stand by and watch happen in Lake Huron.


For the Environment Report, this is Lester Graham.

Related Links

Tracking Long-Term Zebra Mussel Changes

Zebra mussels have been colonizing North American lakes and rivers since 1991. Scientists have looked at many of the ways mussels affect those ecosystems. But a new study underway shows how those effects are moving up the food web…and are having two very different results. The Great Lakes Radio Consortium’s Mark Brodie reports:

Transcript

Zebra mussels have been colonizing North American lakes and rivers since 1991. Scientists have looked at many of the ways mussels affect those ecosystems. But a new study underway shows how those effects are moving up the food web…and are having two very different results. The Great Lakes Radio Consortium’s Mark Brodie reports:


Between 50 and 5-hundred billion zebra mussels now live in New York’s Hudson River. That’s a lot of hungry mouths to feed on the river’s zooplankton and phytoplankton. The problem is the mussels are not the only ones that like to dine on the microscopic plants and animals. A new report suggests the mussels are stealing food from some of the river’s fish.


That’s forcing those fish to look elsewhere for their meals. Sandra Nierzwicki-Bauer is the director of the Darrin Freshwater Institute, and a biology professor at Rensselaer Polytechnic Institute in Troy, New York. She says the zebra mussels can dramatically alter an ecosystem.


“They’re very rapid filter feeders, and as such, they’re able to remove tremendous amounts of phytoplankton, algae, bacteria in the water column. As such, the phytoplankton serves as food sources for other organisms so you really are impacting the entire food web.”


Nierzwicki-Bauer says those impacts go all the way up to fish. David Strayer is a freshwater ecologist at the Institute of Ecosystem Studies, and a lead author of the report on the Hudson River. He says his team studied fish populations in the Hudson both before and since zebra mussels colonized there.


“In open water fish species, we saw a decline in abundance, we saw declines in growth rates, and we saw that the populations of those fish tended to shift downriver compared to the period before the zebra mussel invasion.”


That means some of the most common and popular fish in the Hudson are no longer where they used to be…among them American shad, herring, and white perch. That’s because the zebra mussels are eating those fish’s food…forcing the fish to go elsewhere.


But Strayer says while some fish have had to move away from the mussels…some species have welcomed their new neighbors.


“In the same period of time, we saw populations of fish that live in the weed beds…we saw those populations increase, we saw growth rates of those fish increase, and we saw the populations of those weed bed fish shift upriver into the area where the zebra mussels lived.”


These forage fish have more to eat because the plants at the river’s bottom are growing more. That’s because the zebra mussels clear up the water, which allows more sunlight to reach the plants. Strayer says the zebra mussels have changed almost everything about the Hudson’s ecology.


But he says some of those changes have been difficult to predict, and the changes may not apply to all bodies of water where the mussels have colonized. This is one of the first studies using long term data that looks at the zebra mussels’ affect on fish populations…but there is some evidence that other bodies of water are dealing with similar situations. There have been reports that zebra mussels may be affecting smelt and chub in Lake Michigan…these smaller fish are food for larger species, such as trout and salmon. But while the results are comparable, David Strayer says the changes in the Hudson River are more pronounced than changes elsewhere.


“This isn’t because we have more zebra mussels in the Hudson than in the other places, but it’s because there are differences in the structure of the ecosystem between the Hudson River and the Great Lakes and other places that have been invaded. So, you have to be a little cautious extrapolating from one body of water to the next.”


That sentiment is shared by Andy Kahnly. He’s a fishery scientist with the Hudson River fishery unit of the New York State Department of Environmental Conservation. He also worked on the new study. Kahnly warns for now, the results only apply to young fish…and not adults. That’s because fish can live up to 30 years, and the data don’t go that far back.


“Quite often, changes in early lifestages will take some time to translate into changes in fish populations and then to changes in fish communities. So it takes a lot of data, a lot of years of data to see a change.”


Kahnly says that means anglers in the Hudson might begin to notice some changes over the next few years… and he says the study did find a dramatic decrease in many of the species that people catch.


“If these changes in production of young persist into the future, then definitely there will be a decrease in the abundance of the adults which people are fishing for.”


But that depends on what you’re fishing for. The Institute of Ecosystem Studies’ David Strayer says your perspective might change depending on that you’re trying to catch.


“If you’re concerned about shad populations, if you’re a shad fisherman, then you might be concerned with the zebra mussel invasion and think it’s a bad thing. If you like the weed beds, if you’re a duck hunter or a large mouth bass fisherman this might be regarded as a positive thing.”


Strayer says the study shows zebra mussels are capable of having a tremendous impact on an ecosystem. He says it also shows the importance of being careful to prevent the introduction of invasive species…like zebra mussels…into an ecosystem.


For the Great Lakes Radio Consortium, I’m Mark Brodie.

A Fish Eye View of the Lakes

  • The "Benthic Explorer" now sits on the bottom of Lake Superior and provides live pictures of its underwater world. Photo by Chris Julin.

If you’ve ever been curious about what goes on at the bottom of the world’s largest lake, you can take a look for yourself – and you don’t even have to get wet. A device called the “fishcam” is sitting under 35 feet of water in Lake Superior and it’s now sending pictures to the Internet. Researchers say it’s the only permanently mounted underwater camera in the world sending live images back to shore. The pictures are fun to look at, but researchers say they’re also useful to biologists who study underwater life in the Great Lakes. The Great Lakes Radio Consortium’s Chris Julin has the story:

Transcript

If you’ve ever been curious about what goes on at the bottom of the world’s largest lake, you can take a look for yourself — and you don’t even have to get wet. A device called the “fish cam” is sitting under 35-feet of water in Lake Superior and it’s now sending pictures to the Internet. Researchers say it’s the only permanently mounted underwater camera in the world sending live images back to shore. The pictures are fun to look at, but researchers say they’re also useful to biologists who study underwater life in the Great Lakes.


The Great Lakes Radio Consortium’s Chris Julin has the story.


A team of researchers put the camera underwater more than a year ago. It sits on the lake bottom, several miles from Duluth. The researchers have watched pictures from the “fish cam” for months, but now, anyone with a computer hooked to the Internet can get a scuba diver’s view of the bottom of Lake Superior. The research team recently gathered at the Great Lakes Aquarium in Duluth to unveil the “fish cam” website. Fish expert Greg Bambenek has had the fish cam hooked-up to the computer at his house, but at the aquarium, he watched the fish cam on the screen of a laptop.


“That’s streaming out on the web right now. It’s updated every ten seconds. The fish there are mullet. At night, we have a micro-cam that brings the zooplankton into close focus, and at times you’ll see the mullet eating the zooplankton.”


Those zooplanktons are tiny animals called “water fleas.” They’re fractions of an inch long –far too small to show up through the fish cam’s standard lens. But Bambanek says it’s a different story at night, when the fish cam switches to a magnifying lens, and the computer screen comes alive with little critters.


“Leptodora is the large one. Then you’ll see little copepods that kind of look like Pokemon creatures with the antennas coming off their head, and they’re smaller. They’re only a couple millimeters, so you wouldn’t be able to see them if you were diving in the water.”


The people gathered to see the fish cam’s first Internet images had to settle for a murky picture. A strong northeast wind was blowing in off the lake, kicking up big waves, and stirring up the bottom. The researchers say big waves make for blurry pictures. Even so, lots of fish were visible in the frame. The fish might be crowding in because researchers are releasing fish scent through a special tube attached t the camera. But photographer Doug Hajicek says it’s surprising how many fish swim past even without the fish scent. Hajicek designed and built the underwater camera, and he’s been watching a private feed from the fish cam for months.


“This lake is extremely alive. There is a food chain that is so delicate and tiny. Everybody thinks of Lake Superior as just a sterile body of water, and we’re hoping to change that.”


Some of the fish that swim into view are called ruffe, a non-native species that’s invading the Great Lakes. Researcher Greg Bambenek says it is surprising see so many ruffe here, six miles from Duluth. He says biologists believed ruffe stayed closer to harbors. Bambenek says that’s just one example of the valuable information about life in the Great Lakes that scientists can get from the fish cam.


“We can take freeze-frame, count the number of zooplankton, count the number of fish, and also look at it over time, and also see what does a northeaster do? What do the fish do? Do they leave? Do they come back? What does water temperature do? We have a temperature sensor down there. We also have a hydrophone so we can hear what’s going on underneath the water. So, it is a research tool.”


Bambenek says the research team learned a lot during the year it took to get the camera up and running on the Internet. He says the team is planning to put another camera in Lake Superior, farther from shore, and hopes to put a third camera somewhere on the floor of the ocean.


You can see images from the Lake Superior fish cam at Duluth.com/fishcam.


For the Great Lakes Radio Consortium, this is Chris Julin in Duluth.

Related Links

Zebra Mussels Affect Drinking Water

Researchers know zebra mussels have altered the Great Lakes. They
believe those changes are not finished. The Great Lakes Radio
Consortium’s Lester Graham reports… the invasive species might be
upsetting the food chain and making tap water drawn from the lakes taste
bad:

Tumors Found on Zooplankton

  • Large tumors have been found on zooplankton in Lake Michigan. Scientists don't know the cause and don't know what the growths will mean to the food chain. (Photo courtesy of University of Michigan and NOAA/ Great Lakes Environmental Research Laboratory)

Scientists are alarmed at the discovery of tumors on tiny animals at
the base of the food chain in one of the Great Lakes. The Great Lakes
Radio Consortium’s Lester Graham reports… no one seems sure what this
will mean to life in the lakes:

New Invasive Species Found

A new exotic species is invading the Great Lakes. The Great Lakes Radio Consortium’s Lester Graham reports that this new invader has been causing problems for anglers: