HARRISON — A parasite is to blame for killing white perch in Crystal Lake for about a week, but it is not a threat to humans or wildlife, according to Town Clerk Melissa St. John.

On Wednesday, Heather Mulandi saw at least a dozen 3- to 4-inch perch floating on the water when she arrived at Crystal Lake Beach, beside Route 117. Her son, Kyalo, 8, opted to bury some of them instead of taking them home, she said.

The same parasite caused a die-off of white perch last year at Woods Pond in neighboring Bridgton, St. John said. White perch are the only species affected, and there is no risk to humans or wildlife on the lake, she said.

Town officials have worked with Colin Holme of Lakes Environmental Association in Bridgton to identify the cause of the die-off. 

Parasites are not the only issue fish are facing this summer.

James Pellerin, a state fisheries biologist, said hot, humid weather reduces the amount of dissolved oxygen in water that fish need to live. Smaller fish, such as white or yellow perch, often fall victim, he said.


“It’s a pretty common thing we see this time of year,” he said. “In late July and early August, we’ll see about a half a dozen reports on different lakes.”

The die-offs usually clear up within a day and do not affect the quality of the water for swimming or other activities, he said.

St. John said the oxygen levels in Crystal Lake were tested by the association and found to be fine. 

Pellerin said anyone who spots a die-off, particularly if it involves a variety of species and sizes or it lasts over a long period, should call the Maine Department of Inland Fisheries & Wildlife.

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