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Thursday, September 20, 2012
Still searching for Asian Carp in Lake Erie
Electric probes being used to herd invasive fish
Story by KAREN SCHAEFER
In The Region:You’ve heard the expression that something’s as difficult as “herding cats.” Well, try herding fish! Researchers on the lookout for Asian carp in Lake Erie are using a “herding” technique that involves electric shock probes. As independent radio producer Karen Schaefer explains, the search follows the appearance of carp DNA in the western basin of the lake.
|SCHAEFER: Rich Carter has been spearheading the search for Asian carp in Lake Erie. He’s chief of Fish Management and Research for the Ohio Department of Natural Resources. Carter’s pretty sure the water samples taken from Sandusky Bay contain DNA from the invasive species. But he’s not sure how these big jumping fish got there.|
CARTER: Was it human introduction for these? Potentially. Was it a bait bucket introduction? Potentially. Is it a water source? Potentially. Do we have massive numbers of these fish swimming around? You know, based on all the sampling that we’ve done, the evidence suggests that if fish are present, they’re present in very low densities.
SCHAEFER: Earlier this week Carter was out on a boat on the Sandusky River about four miles from the bay, watching U.S. Fish & Wildlife Service biologists lay a gill net across the river. They’re herding fish into the net with two boats equipped with electric shock probes inserted into the water that drive the fish before them. It’s a technique called electrofishing. Carter watches and listens carefully as one of the biologists lifts a large fish from the net.
CARTER: That was a buffalo. I think he was saying is that a lot of people confuse buffalo for Asian carp.
SCHAEFER: So far this summer, after two intensive sweeps, no Asian carp have been found in either Sandusky or Maumee Bays, or their river tributaries. Carter says he’s pretty sure that means there are not yet breeding populations of Asian carp that could compete for food with new hatches of native sport fish like walleye and perch. The carp usually win the competition.
SCHAEFER: One potential pathway for the carp into the lake is Eagle Marsh in Indiana, where heavy flooding could spill the carp from the infested waters of the Wabash River into the Maumee. Another is the Chicago sanitary and ship canal, the primary entry point for Asian carp into Lake Michigan. Rich Carter says no carp DNA has been found anywhere near either one of these pathways so far, but officials are still awaiting water sample results taken in August. A third possible explanation for carp DNA in Lake Erie could be bait shops along the coast.
CARTER: We know that some bait comes from southern waters. Asian carp are present in Arkansas and Mississippi and some of those areas. So we’re exploring and eliminating uncertainty.
SCHAEFER: Results from those bait shop tests are still pending, too. Carter estimates this year’s search for Asian carp has already cost up to 300-thousand dollars. Even so, that pace is too slow for some environmental advocates. Sandy Bihn of the Western Lake Erie Waterkeepers Association calls the presence of carp DNA in Lake Erie a 5-alarm fire.
BIHN: As we saw with zebra mussels and quagga mussels, we didn’t do anything, we just let them come and they multiplied incredibly. We should learn a lesson from that.
SCHAEFER: Bihn is also concerned that there’s no plan to manage the fish if Asian carp do establish themselves in the lake. One rather drastic option is to kill all the fish in an infested area using a poison called rotenone. The poison doesn’t discriminate, though – it would kill other fish, too.
BIHN: I would hope that scientists take a look and develop a plan of what to do if they find them here, because I think the fact that the DNA are found now deserves the next level of attention.
SCHAEFER: Rich Carter of the Natural Resources Department says scientists are working on better solutions, including species-specific poisons - and having the carp mate with genetically-engineered fish.
CARTER: …fish that are placed in the water that eventually breed with the other fish that are present in the water and make them reproductively sterile. But today, there’s not a good tool for control.
SCHAEFER: For now, the mystery of how Asian carp DNA got into Lake Erie goes on…as does the hunt for clues.
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