Winter at Henrys Lake Still Looks Good for Trout

Winter winds are still gusting, and it's almost three months until anglers will be able to legally hook a fish. But when you're responsible for managing a world-class fishery like Henrys Lake, you can't afford to turn your back on things for even a minute. Idaho Department of Fish and Game assistant hatchery manager Damon Keen maintains a vigil over the lake and its scaly residents throughout the long, cold Island Park winter. Some of the same factors that have made Henrys Lake such a productive place for trophy trout can also lead to major problems when a variety of negative factors coincide. The lake is shallow, averaging only about 16 feet and full of aquatic vegetation. But when the lake freezes over and sunlight cannot penetrate, the vegetation can use up much of the dissolved oxygen in the water. This winter the ice was about 20 inches thick. "We start taking oxygen readings at the end of December and use an oxygen depletion model to forecast whether or not we will see low oxygen conditions," Keen said. "Due to the readings this winter, aeration was not deployed." Not only is this good news for the fish and the anglers, it's also good news for Fish and Game's wallet. Operating the aeration system can cost tens of thousands of dollars in electricity. Keen is also watching the behavior of the fish. "The fish ladder will be open for spawn take on March 1," he said. "March is the best time to see the fish in the fish ladder." Visitors to the facility can take advantage of large informational signs, posted outside near the fish ladder, that explain the hatchery operations. In addition to keeping an eye on oxygen in the lake, fishery biologists have been keeping their ears to the ice as well, or at least figuratively speaking. This year Fish and Game, in cooperation with the Henrys Lake Foundation, has outfitted 43 trout with radio tags to help track seasonal movements of the fish. Weekly observations of the fish have shown that the trout make use of the entire lake throughout the winter, but they tend to favor areas along the shoreline. The tracking project will be ongoing to help provide an idea about spawning activity. Anyone wishing to learn more about conditions at Henrys Lake may contact the Upper Snake Regional office at 208-525-7290, or the Henrys Lake Hatchery at 208-558-7202.