An angler ice fishing for trout on Island Park Reservoir on January 3, 2026, unexpectedly caught a 5-inch Yellow Perch, a species that does not belong in the reservoir. The angler reported the catch immediately to the Citizens Against Poaching hotline.
Idaho Fish and Game Conservation Officers met the angler on the ice and confirmed that the fish was indeed a Yellow Perch. With no nearby Yellow Perch fisheries, authorities determined the fish was illegally stocked, marking the first confirmed report of Yellow Perch in Island Park Reservoir, which is managed as a hatchery-supported Rainbow Trout fishery.
“Transporting live fish in Idaho without a permit is illegal,” said Fisheries Manager Brett High. “Illegal stocking can have serious ecological consequences, and individuals responsible may be held liable for the financial costs to restore the fishery. Restoration could total hundreds of thousands of dollars and may include felony charges.”
High noted that the introduction of Yellow Perch could impact trout populations. “Trout are Idaho’s most popular species and feed on small crustaceans, or zooplankton, in our reservoirs. Perch eat the same food and can sometimes out-compete trout, affecting survival and growth. How this illegal introduction may affect ongoing water quality and fishery improvement efforts in Island Park Reservoir is unknown and concerning.”
Idaho Fish and Game is encouraging anglers to harvest any Yellow Perch caught in the reservoir, with no bag or size limits.
Conservation Officers cannot patrol all areas at once. Anyone witnessing illegal fish transport or other wildlife violations is urged to call the Citizens Against Poaching hotline at 1-800-632-5999. Callers may remain anonymous and could be eligible for a reward.