In 2009, Minnesota treated Pickerel Lake with fish poison to remove common carp; afterward water clarity rose nearly 600% and plant cover climbed from 4.6% to 90%

For decades, Pickerel Lake in Minnesota struggled with poor water quality, heavy algal growth and extremely low aquatic plant cover. The shallow lake had become dominated by common carp, a bottom-feeding fish that can disturb lake sediments and alter the movement of nutrients through an aquatic ecosystem.

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