The annual migration of fish presents a unique opportunity for researchers at the University of Minnesota testing a new way to stop the spread of invasive carp.
The Minnesota Aquatic Invasive Species Research Center (MAISRC) is on Rice Creek experimenting with a Whooshh System.
U of M scientists call it a Carp Cannon, but it's actually designed to help salmon migrate over dams for spawning.
MAISRC researchers are the first in the world to use it to stop the spread of invasive fish; in this case the common carp.
"Well, the problem with them is they are too common," Dr. Przemek Bajer said. "There's very many of them. They dominate fish bio-mass in a lot of lakes."
According to Rice Creek Watershed District Lake and Stream Specialist Matt Kocian, carp dig in the bottom of lakes looking for food.
"They cause some really bad water quality problems," he said. "They create algae blooms and they make algae blooms worse."
It is estimated that there are 12,000 carp in Long Lake. And every spring, at about the same time, they all migrate up Rice Creek toward Lino Lakes to spawn.
The trap is set up on Rice Creek to force them into the carp cannon. The carp are then guided to their demise using electricity.
"But it's basically an electronic fish barrier," Kocian said. "But it's low voltage, so it doesn't stun the fish."
For now, the carp swim into a net. Then they are dumped in a boat, euthanized and sucked away.
Things are still being fine-tuned, but eventually, the fish will swim right into the carp cannon.
The goal is to reduce the number of carp to a level where they don't cause problems.
"But you know, if we're starting at 12,000, if we can cut them down by 90 percent, then we're going to be pretty happy," Kocian said.
So far, they have removed about 4,500 carp from Rice Creek, which is about 36,000 pounds of invasive fish.
Many have been donated to the Wildlife Science Center for wolves to eat. The rest are disposed of.
The Rice Creek Watershed District is receptive to other ideas for using the carp if anyone in the public has any.