Tags monitor common carp

A University researcher is mapping carp movements to help control the population.

Ryan Faircloth

A University of Minnesota professor hopes to reel in invasive species in the state by implanting fish with electronic tags.
Fisheries and wildlife professor Peter Sorensen is tracking the movement of carp in the Rice Creek Watershed District in Blaine, Minn. 
His research is part of a project funded by the National Science Foundation that aims to reduce the carp population by tracking their movements. 
Monitoring carp movement will help researchers to control the species’ population, said Nate Banet, fisheries and aquatic biology graduate student and research assistant.
“Nate is tracking common carp with radio tags to monitor how far they might move, when they might move and what their patterns of movement are so that eventually, we can
understand them better and develop some control methods for them,” Sorensen said.
He said the fish have lifespans lasting up to 50 years and can multiply rapidly. Common carp become invasive when their numbers grow, he said. 
“When they do reproduce successfully, it’s in huge numbers, so you get massive bursts,” Sorenson said.
Common carp feed on plants at the bottom of lakes, spit them out and make the lake mucky, Banet said, which is why they’re classified as an invasive species.
By tracking the low frequency signals emitted by the implanted tags, Banet can see where the fish travel in Rice Lake throughout the seasons.
However, carp can travel up to five miles in about two hours, Sorenson said, which makes tracking their migration difficult to do.
“They have spatial memories, and they understand these lakes and how they’re put together. So, they will actually go back to the lake they were born in,” Sorensen said.
Though scientists have struggled with managing common carp in the past, Banet said he thinks he’s found a couple different strategies that could prove successful, including trapping and catching them in narrow areas of the lake.
In his research, Banet discovered a majority of adult carp they tagged migrated upstream to a small creek about 15 feet wide every spring.
“That’s a prime example of a chokepoint of where these fish are migrating,” he said.
Banet said the fish can also be controlled during the winter when they form compact groups under the ice. 
Fishermen can then use large nets to collect the clusters of carp and pull them out of the water, he said.
While Sorenson and Banet’s strategies may help manage the carp population in Rice Lake, some experts think it’ll take further research to manage carp invasion across the state. 
Nick Frohnauer, the invasive fish and river habitat coordinator for the Minnesota Department of Natural Resources, said the researchers’ work in Rice Lake is promising, but
because the makeup of lakes can vary across the state, their methods aren’t guaranteed to work everywhere
“What might work in one spot might not be the best in another spot,” Frohnauer said. “Good management is going to rely on a variety of tools that we can employ.” 
He said continuing to research carp removal might allow scientists to adapt current methods of management to slightly different areas.
Sorenson hopes to understand the extent of the common carp invasion and to develop new methods to control them.
“I believe that once we understand them better, we will produce tools to help us control them better,” he said. “Long-term gains come through long-term deep understandings.”