Development and Simulated Use of a YY Male Brook Trout Broodstock for Potential Eradication of Undesired Brook Trout Populations

Brook Trout introduced outside their native range often negatively impact native aquatic fauna, but complete eradication of such populations with electrofishing or rotenone is difficult to achieve. A potential alternative is a Trojan Y Chromosome (TYC) program, where hatchery-produced genetically YY male fish would be regularly released into an undesired population over time, skewing the population towards 100% males, theoretically resulting in wild population extirpation. We developed two genetic sex markers for Brook Trout and employed juvenile sex reversal methods commonly used in commercial aquaculture to develop a YY broodstock that can produce offspring for possible future use as biological control agents. Our genetic sex markers proved successful with genotypic sex determination for both assays matching the observed phenotype for 90 out of 90 individuals. Estradiol-infused feed readily feminized genetic XY males into neo-females at a high rate (99.6%, n = 224). We then cultured sperm and egg-producing supermales, a vital step towards development of TYC technology on a large aquaculture scale. This study demonstrates that hatchery production of a YY Brook Trout broodstock is feasible, modest in cost, and can be completed in less than 4 years. Stochastic population simulations of timelines for eradications are also presented.