Tag: large mouth bass

Invasive Species at the Aquarium

  • Asian carp are one of the invasive species featured in the exhibits in your local museums. (Photo courtesy of USFWS)

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.


For the GLRC, I’m Shawn Allee.

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.