Carp Management | Prior Lake Spring Lake Watershed District

Tony Havranek, from WSB & Associates, tracking the tagged carp.

Location: Waterbodies Across the District
Project Type: Capital Projects
Project Status: Active
Current Status: Phase II of carp management program. See below for more details and view our 2020 Carp Management StoryMap.

CARP SEINE UPDATES:

Many factors must be aligned before a carp seine will be pursued in order to maximize the success of the seine. Factors required for a successful winter seine include: proper ice thickness, large grouping of carp in a location suitable for seine nets, appropriate outside temperatures, commercial fishermen available and willing to conduct the seine and demand in commercial market for carp.

You can CLICK HERE to find updates on District seining efforts, along with a map of carp locations in the lakes. Carp seines are used to remove common carp from District waterbodies using large seine nets to corral carp together for removal.

What is a carp seine? View video here

How do we track the carp? Find out with our StoryMap here

About this Project:

In 2002, Spring Lake and Upper Prior Lake were listed on Minnesota’s 303(d) List of Impaired Waters for nutrient/eutrophication biological indicators and aquatic recreation on both lakes is impaired. The 2012 Spring Lake and Upper Prior Lake TMDL Implementation Plan identified internal loading, including the load from rough fish (e.g. carp), as a source of roughly half of the phosphorus internal loading to the lakes. The plan went further to identify rough fish management as a way to significantly reduce estimated phosphorus loading.

The District’s carp management project maximizes water quality restoration and remediation by addressing one of the root causes of internal loading identified in the TMDL for Spring and Upper Prior Lakes: common carp. Carp stir up sediment from the lake bottom when they forage for food. This re-suspended sediment makes more phosphorus available to phytoplankton and increases the shading effect on native submergent aquatic vegetation. Aquatic vegetation sequesters phosphorus but when the plants do not receive as much sunlight, the plant populations will be reduced and less phosphorus will be stored in the plants. Carp also feed directly on or uproot vegetation, further increasing the level of phosphorus in the water column. By removing the carp from the system, both the phosphorus within the carp carcass and the amount that would typically be excreted will be completely removed, while also abating the release of phosphorus created by foraging behavior.

As a result of the 2012 TMDL Plan, the District began building a comprehensive carp management program to address the internal loading in Spring and Prior Lakes. In 2017, the PLSLWD developed an Integrated Pest Management Plan to reduce the common carp population in the District’s priority lakes, looking at the system as a whole. This plan is meant to be a working document which is updated each year as new strategies and goals are incorporated into the plan.

This project uses integrated pest management (IPM) principles to effectively manage the common carp population within the basin. IPM involves the use of targeted carp removal methods, barriers to spawning grounds, and biological controls to limit carp recruitment, as well as monitoring environmental parameters that can inhibit or promote carp population growth within the Spring and Prior Lakes basins. Adaptive management will use the carp population data that is collected including population and biomass estimates as well as migration routes and winter aggregation locations.

Current Work: Phase II

The District is currently in Phase II (2019-2021) of implementing an integrated pest management for carp. The District is working with WSB & Associates and funding is partially provided by a Federal 319 Grant and a BWSR Watershed Based Funding Grant.

Phase II builds on what was learned about the carp populations in Spring and Prior Lakes during Phase I. Data collection will continue to refine our understanding of where & when the carp migrate, improve the success of removal efforts and update carp population estimates. The goal is to reduce and then maintain the carp population below the management target level at which they are no longer causing significant harm to the lake ecosystem, as total eradication of common carp from the lakes is not considered practically achievable.

While work in Phase II continues Phase I work in Spring and Prior Lakes, the District will also expand the carp management efforts to other connected waterbodies in the District including Buck, Fish and Pike Lakes, as well as the Geis wetland. The goal is to learn more about the carp populations in these waterbodies to identify what management strategies are necessary.

In 2019, 18 carp were tagged with radio-tags, including 9 carp on Upper Prior and 9 carp on Spring Lake. An additional six carp were tagged in 2018 on Upper Prior Lake. The radio-tag batteries last roughly two to three years before the batteries die and the signal is lost. The tags allow the District to track the movements of the carp and identify the areas where the carp congregate. Knowing areas the carp like to gather will permit the District to target these areas for management of the invasive carp.

For SEINE UPDATES: Click here for more info.

In 2020, the District expanded its carp management toolbox and experimented with many new methods for carp removal including several types of traps (Newman trap, Anderson trap, baited box traps), baiting carp and smaller removal events. To see photos and find more detailed explanation, check out our 2020 Carp Management StoryMap!

Radio tagging carp on Prior Lake in January 2016.

Phase I Summary (2015-2018):

More details can be found on the Phase I Carp Management page.

During Phase I, roughly 30 carp were radio-tagged in Spring and Prior Lakes; the first 15 carp were tagged in the Fall & Winter of 2015-16 and an additional 13 carp were tagged in 2016 & 2017. This allowed the District to track the movements of the carp through the lakes and connected waterbodies. Tracking helped the District locate the carp when they group up together, enabling more successful carp seine events. For a video showing how the radio-tags are inserted into the carp, visit the PLSLWD YouTube Channel. Population estimates for the carp population in Spring and Prior Lake were gathered by using a mark-recapture method.

Radio-tags have also helped identify areas the carp use to spawn in the spring and have helped determine locations for carp barriers to prevent adult carp from reaching their ideal spawning areas. Denying the carp access to their preferred spawning areas should reduce the carp population growth in Spring and Prior Lake.

Successful carp seines during Phase I included:

January 2017 Seine: A seine event on Spring Lake in January 2017 caught 2,577 carp weighing 17 TONS! That’s over 34,000 pounds of carp removed from Spring Lake. You can check out some awesome photos (with explanatory captions) from the seine on Facebook page.

January 2018 Seine: In a record-setting event on January 18, 2018 the District’s carp consultants, WSB & Associates, coordinated the efforts by Geyer Commercial Fishing to capture an astounding 35,000 pounds (17 tons) of carp with their nets below the ice of Upper Prior Lake. This big carp haul represents only a portion of the total carp population in Upper Prior Lake. While approximately 3,000 carp were removed, that’s estimated to be just under 20% of the population; an estimated 17,000 carp (approximately 100,000 lbs.) may still be swimming in the lake.

Previous Efforts

The PLSLWD has had successful seines, particularly on Spring Lake in the past, but prior to 2015 efforts were sporadic and not done in concert with other control efforts.

Anticipated Outcomes

Reduction of carp population to below damaging levels and improvement of the ecosystem. By removing the carp from the system, both the phosphorus within the carp carcass and the amount that would typically be excreted will be completely removed, while also abating the release of phosphorus created by foraging behavior.

Informational Materials

GRANTS

Federal Clean Water Act Section 319 Grant

This federal grant program is managed by the MN Pollution Control Agency (PCA). This three year grant (Feb. 2019- Dec. 2021) will help fund carp management in Spring and Upper Prior Lakes.

Management activities include: tracking movement and population of carp; complete seine (netting) and other removal events; installing carp barriers at strategic locations; native aquatic plant establishment; and community outreach.

BWSR Watershed Based Funding Grant

This grant program is managed by the Board of Water & Soil Resources (BWSR) through the Clean Water Fund. This grant provides funding for carp management, feasibility studies, & Farmer-Led Council programming and is available from May 2019 until December 2021.

The carp management portions of the grant includes: Monitoring & data collection of carp population and movement, as well as aquatic plant surveys; installation of carp barriers; carp removals using seines and other techniques; and education & outreach.

Clean Water Partnership Grant

This grant program is managed by the MN Pollution Control Agency (PCA). This three year grant founded carp management in Prior Lake and Spring Lake from 2015-2018. Management activities included tagging 30 carp with radio-tags, tracking the carp in Prior and Spring Lakes to determine seasonal aggregation areas and spring spawning areas and installing carp barriers in strategic locations to prevent carp from reaching their preferred spawning areas. Radio-tag tracking was also used to help improve the success of carp removals; the radio-tags allowed the District to identify went and where the carp were aggregating and then seine those areas to remove carp.

Conservation Partners Legacy Grant

This grant is funded by the Clean Water, Land & Legacy Amendment through the MN Department of Natural Resources (DNR). This grant funded the installation of a drum barrier at the District’s desiltation pond for the ferric chloride facility to prevent carp from using the pond for spawning.

https://youtu.be/1GKxy_I8svM