Thursday, December 18, 2014

Carp Research Wraps Up for the Holidays

By: Bill Bartodziej

The University of Minnesota research project on common carp in the Phalen Chain of Lakes is now complete. Key products from this effort:

  1. We reduced the adult carp population in the Chain by over 50% - down to 58 pounds per acre. This meets our goal of having the adult population under 90 pounds per acre where negative water quality impacts are evident.
  2. Carp spawn in the main lakes, but bluegill sunfish effectively eat carp eggs, and this limits the number of young carp being produced in the lakes.
  3. We found several carp nursery areas that drain into the Phalen Chain of Lakes (with thousands of young carp). Small carp from these systems can find their way into the Chain. These systems will be actively managed to eliminate carp over the next several years.
  4. Several science journal articles have been written on this work. Data is being shared with researchers and managers on an international level.    

Map showing carp nursery areas that drain into the Phalen Chain of Lakes. The red highlighted waters indicate carp nursery hot spots.  (YOY = Yong of Year Carp)

The U of MN research team and Watershed staff are in the process of finalizing a carp management plan for the Chain. This is a long-term plan with components that are already being carried out by Watershed staff. 

No Carp Netting this Year?

So although winter netting under the ice on Lake Gervais is exciting, fun, and full of the “wow” factor, we have come to the point where the adult carp population is at a relatively low level. Water quality impacts from a population this size is not a concern.

However, this doesn’t mean that our work is done. An extremely vital component in the carp management plan is to keep young carp from finding their way into the Chain’s main lakes. Thus, we are shifting our efforts and going after the young carp in the target nursery areas, specifically Casey Lake, Markham Pond, and the Interstate Ponds. This is less impressive work on the surface, but a very critical component in keeping carp levels low in the Phalen Chain. 

Casey Lake Management

Over the last couple of years, we have been able to eliminate carp in Casey Lake. This was identified as a carp nursery hot spot. We have worked with the DNR and the City of North St. Paul to stock bluegill, and aerate this system over the winter. This effort will have direct positive impacts on Casey’s fishery and water quality. At the same time, we eliminated a significant source of carp that were threatening the entire Chain. 

With the aeration system in place, open water can now be seen in the middle of Casey Lake - December 2014.

On Markham Pond

This winter, we are working to eliminate carp in Markham Pond. Under a DNR permit, we began a draw-down of the system this fall. We were able to lower the pond level by about three feet. The maximum depth of the pond is four feet, mainly by the west end near the pond outlet.

During one of our upcoming severe January or February arctic blasts, we plan to pump the remaining water (under the ice) out of Markham, with the goal of freezing out the deeper pockets. Carp taking refuge in these areas will likely be eliminated. Once all of the carp are gone, we will partner with DNR and the city to stock bluegill and install an aeration system. This will safeguard against a carp re-infestation.

Again, this is definitely not as interesting as pulling nets under the ice on Lake Gervais, but it is very important work that will have lasting benefits to the entire Chain of Lakes.

After the draw-down, a large school of carp taking refuge in a deeper spot in Markham Pond - November 2014.

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