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MINNEAPOLIS - Federal and state leaders highlighted the Upper St. Anthony Falls Lock and Dam in downtown Minneapolis as a crucial barrier to stop the Asian silver carp's advance up the Mississippi River.

Sen. Amy Klobuchar and Rep. Erik Paulsen visited the site Monday to tout legislation they introduced last week to make it easier to close the lock and dam.

Meanwhile, University of Minnesota researchers at a nearby laboratory are studying bubble curtains and other potential ways to stop carp.

The curtain is essentially made up of air bubbles that annoy carp.

"The sound and the turbulence is enough to essentially kind of freak out the fish to want to stay away," said Dan Zielinski, a University of Minnesota PhD civil engineering student. "Or you can use it to direct them towards a trap that you maintain."

As it turns out, carp - including silver ones - are sensitive to loud noises. The bubbles the curtain creates are as loud as a jack hammer to the fish. The turbulence in the water only adds to the annoyance.

"A barrier similar to this in a circular tank we were able to reduce the number of times they crossed by 75 percent," said Zielinski.

Those results were for the common carp, but a similar result is anticipated for the silver. It's obviously not a solution, but it's a start.

The U of M will test its bubble curtain on June 1, 2012, at Kohlman Creek, which is connected to the chain of lakes that includes Lake Phalen.

The University will add tagged fish to the creek and fish will also be taken and tagged to keep track of just how effective the bubble curtain can be.

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