Using management techniques developed on the Phalen Chain of Lakes, we’re now working to reduce carp and improve water quality in the Lake Owasso system.
Carp Management – Lake Owasso Chain
Project Details
| Cities | Shoreview, Roseville |
| Subwatersheds | Lake Owasso, Lake Wabasso, Bennett Lake |
| Timeline | Ongoing since 2017 |
| Cost | $40,000 (2021 budget) |
| Funding sources | District funds |
| Partners | University of Minnesota, Minnesota DNR, City of Shoreview, City of Roseville, Ramsey County |
Overview
Carp management in Lake Owasso and connected lakes is one of the tools we use to reduce phosphorous loading in these waters. As carp root for food along the lake bottom, they stir up nutrient-rich sediment, which in turn contributes to turbid water, phosphorus release and algae blooms.
With four interconnected lakes (Owasso, Wabasso, Bennet and Grass) and 12 shallow ponds, the Lake Owasso system offers prime habitat for carp to potentially out-compete native game fish, uproot aquatic vegetation and harm water quality.
Counting carp
In summer 2017 we enlisted Carp Solutions Inc. to conduct a carp population assessment through electrofishing. After calculating a carp biomass estimate, it was found that each lake in the chain contained more than 100 pounds of carp per acre, the threshold generally considered to negatively impact water quality. Most concerning were Lake Owasso and Lake Wabasso, which each turned up more than 400 pounds of carp per acre.
The Carp Solutions team marked over 200 carp with a fin clip as part of a mark-and-recapture study to verify these estimated population numbers, and they surgically implanted radio transmitters in 20 adult carp. Since carp tend to travel in dense schools, the radio-tagged fish will help us track seasonal movements of the larger population. This allows us to pinpoint the best locations to efficiently harvest carp, along with where to place barriers that prevent them from accessing shallow spawning and nursery areas.
Carp nurseries
While netting has reduced the adult carp population, confirming spring spawning locations is important for a sustainable, long-term management strategy. Shallow ponds and wetlands often serve as carp nurseries where they can hatch by the millions and grow in relative safety from predators. In spring 2018, we installed PVC barriers at five key locations on the Lake Owasso Chain to prevent adult carp from reaching these spawning areas. During spring migration we successfully removed several hundred carp from these areas using handheld nets and electrofishing equipment. In the years since we have refined barrier design and placement in these lake connections, leading to continued success with targeted carp removal.
Results to date
In all of the managed lakes, carp biomass is now below the 100 lb/acre threshold where substantial water quality and ecological impacts take place – charts showing these reductions are posted below. We will continue to work towards further reductions in these lakes while exploring opportunities to begin carp removal in Grass Lake.
More information
As interest in management of common carp populations grows, so does Carp Solutions (Star Tribune)
Box nets and barriers help manage common carp on Owasso Chain