Lake Trout populations in western U.S. waters have been shown to have adverse impacts on native or desirable fish species and are often targeted for manual removal. The population in Lake Pend Oreille, Idaho has been successfully suppressed to levels that have permitted the rebound of the primary forage population and more recent use of the same approaches in Yellowstone Lake Wyoming have allowed native Yellowstone cutthroat there to begin rebuilding. Despite these apparent successes, annual suppression costs on these two waters has recently ranged from 1-2 million annually , amounts far above those available for successful Lake Trout eradication in most other western waters. Alternative or complementary methods that could be used to control or completely eradicate Lake Trout populations are needed. YY Males, which are created in the hatchery by feminizing XY males then crossing them with normal XY males, comprise another approach to eradicating undesirable populations. If stocked YY Males survive and reproduce with wild females, it could eventually drive the wild population sex ratio to 100% males, at which point the population would be unable to reproduce and be eradicated after stocking ceased. A sizeable YY Male Brook Trout broodstock has been developed and is currently being field evaluated by stocking in 16 Idaho waters . The present study documents the first step in companion efforts to develop a YY Lake Trout Broodstock for similar wild Lake Trout eradication evaluations . Lake Trout eggs were obtained on 16 October, 2016 by spawn crosses at the Story Fish Hatchery in Wyoming , transferred to the Grace Fish Hatchery in Idaho and placed in Heath trays. Newly hatched fry (n= 120) were transferred to 24 individual 3.75 gal pots and treated with one of 12 treatmen ts. Treatments tested included immersion (200-400 microg/L), top-coated feed for 97 d beginning at first-feeding , and immersion-feed combinations involving both Estradiol and Estrone as the feminizing hormone . Growth and survival were monitored periodically and compared to controls. Numbers were culled to 35 fish per tank to prevent overcrowding. A total of 840 fish averaging 82.3 mm were removed from the 24 pots in June 2017 , PIT tagged and reared in a common garden raceway until sex could be readily determined visually. Mean growth rates (in length and weight), mortality rates, and observed sex ratios f ollowing necropsy for all treatment and control groups will be reported and next steps in development of a YY Lake Trout broodstock discussed.