Researchers pitch ideas for carp reduction after Six Mile Creek assessment findings

(Minnesota Aquatic Invasive Species Research Center)

Minnesota Aquatic Invasive Species Research Center (MAISRC) researchers recently completed a three-year assessment of the abundance, seasonal movements, and recruitment patterns of common carp in the Six Mile Creek sub-watershed, and researchers found that the total biomass of carp in the sub-watershed is approximately five times greater than a threshold that was previously identified to cause severe ecological impacts.

In order to reduce the carp population to a less damaging level, researchers made numerous management recommendations, including:

  • Identifying important carp nursery habitats across the sub-watershed that need to be addressed in order to suppress recruitment and prevent the carp population from growing. Management recommendations include installing barriers and maintaining dissolved oxygen levels through the use of aeration. Aerating will help restore and maintain healthy native fish communities with species that have been shown to control carp recruitment by consuming their eggs and larva.
  • Providing specific target numbers for the removal of adults in order to reduce existing biomass below 100 kg of carp per hectare – using seining, trapping spawning migrants, baited traps, water drawdowns, and/or piscicides.
  • Delineating the area into four or five appropriate management units, after identifying multiple subpopulations of carp based on movement patterns and recruitment dynamics.

The Six Mile Creek sub-watershed is a particularly complex series of 17 interconnected lakes, plus numerous ponds and wetlands, which is different from previous MAISRC carp control study locations. Many lakes in the sub-watershed are highly degraded and have areas that are devoid of submersed native plants – likely attributable to common carp.

The project, which was funded by Minnehaha Creek Watershed District, was spurred by a study that identified carp as one of the major drivers of poor water quality in the sub-watershed. The full report is available here.

Common carp are one of the world’s most widely introduced and invasive species of fish. Currently, they dominate the fish biomass of many shallow lakes, rivers, and wetlands in North America and around the world, including many lakes in central and southern Minnesota. They degrade water quality and destroy waterfowl habitat by rooting in the lake bottom while searching for food. Learn more about common carp and the aforementioned research here.

— Minnesota Aquatic Invasive Species Research Center

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