An Evaluation of Close Cut Weed Harvesting

Excessive and dense vegetation is a common fish management concern in Wisconsin Lakes. Although weed harvesting is typically focused on recreational improvements little consideration was given to the consequences on fishes. That is until a study was performed to determine how close-cut harvesting can be used as a whole-lake fish management program.

A conventional weed harvester was modified by Dane County Parks Department in Madison Wisconsin, by adding a hydraulic arm mounted at the rear and fitted with a 1.8m wide cutting bar that allowed a variable cutting depth of 1 to 6.5m. A hydroacoustic depth finder mounted near the steering wheel is monitored by the driver and allows him to raise and lower the cutter bar to maintain a cut .6m above the sediment.

The study demonstrated that the close-cut harvester is an effective tool to create edge habitat in dense beds of Eurasian Watermilfoil while traditional weed harvesters have success in maintaining boating access in shallow water. During the fourth year it was determined that the habitat created by the close-cut harvesting has had positive effects on growth rates and size structures of the fish.

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