WAUSAU, Wis. — The ice fishermen spent a week on the frozen lake, and on the last day, after emptying perch and bluegill from their buckets and scrubbing bait from their hands, several winners of the World Ice Fishing Championship were ushered into their rooms in the Plaza Hotel.

There, an official from the United States Anti-Doping Agency ordered them to provide urine samples for a surprise test to detect steroids and growth hormones — drugs not normally associated with the quiet solitude of ice fishing.

“We do not test for beer, because then everybody would fail,” said Joel McDearmon, chairman of the United States Freshwater Fishing Federation.

With doping a rampant problem throughout sports, drug testing has arrived at the most unlikely places, including the chilly Big Eau Pleine Reservoir, where competitors hide fish in their pockets and prize patience over power.