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Brook Trout Salvelinus fontinalis have been introduced across the western USA, where the species competes with and often replaces native salmonids. Nonnative Brook Trout are difficult to eradicate; thus, new removal strategies are needed. One novel methodology couples the partial suppression of wild Brook Trout with the replacement of MYY Brook Trout (males with two Y chromosomes). If MYY fish survive to reproduce with wild female Brook Trout, their progeny will be 100% male, which eventually shifts the sex ratio and theoretically extirpates the population. However, the effectiveness of this approach depends on survival and reproduction of MYY fish relative to the surviving wild conspecifics. From 2018 to 2020, we annually removed an estimated 45.7% of wild Brook Trout from three streams in New Mexico and stocked fingerling MYY Brook Trout (mean TL = 94 mm; range = 61–123 mm) targeting 50.0% of wild annual abundance estimates. Annual survival for MYY and wild Brook Trout was similar in Leandro Creek (MYY = 0.63 and wild = 0.63) and Rito de los Piños (MYY = 0.37 and wild = 0.46) but differed in Placer Creek (MYY = 0.28 and wild = 0.75). During spawning, we evaluated the reproductive potential of MYY Brook Trout by comparing the percentage of sexually mature male Brook Trout comprised of MYY fish to the percentage of hybrid (MYY × wild) F1 progeny. By the second spawning season (2019), MYY fish comprised 59.8, 50.4, and 34.5% of milt‐producing Brook Trout, which resulted in 55.1, 33.3, and 0% hybrid progeny in Leandro Creek, Rito de los Piños, and Placer Creek, respectively. We demonstrated that MYY fish exhibit similar vital rates compared with wild conspecifics in two of three streams; however, differences among streams highlights unforeseen variables that influence MYY survival and reproduction. The study offers promising results of the MYY approach for potentially eradicating unwanted Brook Trout populations. [ABSTRACT FROM AUTHOR]

Bayesian clustering methods have emerged as a popular tool for assessing hybridization using genetic markers. Simulation studies have shown these methods perform well under certain conditions; however, these methods have not been evaluated using empirical data sets with individuals of known ancestry. We evaluated the performance of two clustering programs, baps and structure, with genetic data from a reintroduced red wolf ( Canis rufus) population in North Carolina, USA. Red wolves hybridize with coyotes ( C. latrans), and a single hybridization event resulted in introgression of coyote genes into the red wolf population. A detailed pedigree has been reconstructed for the wild red wolf population that includes individuals of 50-100% red wolf ancestry, providing an ideal case study for evaluating the ability of these methods to estimate admixture. Using 17 microsatellite loci, we tested the programs using different training set compositions and varying numbers of loci. structure was more likely than baps to detect an admixed genotype and correctly estimate an individual's true ancestry composition. However, structure was more likely to misclassify a pure individual as a hybrid. Both programs were outperformed by a maximum-likelihood-based test designed specifically for this system, which never misclassified a hybrid (50-75% red wolf) as a red wolf or vice versa. Training set composition and the number of loci both had an impact on accuracy but their relative importance varied depending on the program. Our findings demonstrate the importance of evaluating methods used for detecting admixture in the context of endangered species management. [ABSTRACT FROM AUTHOR]