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populations adapt to the hatchery environment, a process called inadvertent or domestication <br />selection (Doyle et al. 1995). Domestication is thought to result in genetic changes that affect <br />the fitness of a population (Ford 2002). Domestication can occur because of culture practices <br />that favor certain genetic backgrounds or occur because of the relaxation of selection, thereby <br />allowing maladaptive genotypes to persist (Hard 1995; Lynch and O'Hely 2001). <br />Domestication selection is viewed as a problem when hatchery fish are less adapted to the natural <br />environment than wild fish. The negative impact occurs in wild populations when the overall <br />population fitness of wild stocks genomes are swamped with genetic backgrounds adapted to the <br />hatchery environment (Ford 2002; Lynch and O'Hely 2001). "Natures" rearing practices initiated <br />at Dexter NFHTC in conjunction with an intensive genetic monitoring program will provide the <br />information and culture methodology necessary to mitigate domestication selection. <br />Strategies to minimize risks <br />Dexter NFHTC basic strategy to propagate and manage captive RBS broodstock <br />populations will be based on the best scientific information available: the use of molecular genetic <br />data (Ferguson et al. 1995; O'Reilly and Wright 1995). Dexter's plan acknowledges that standard <br />hatchery practices are sources of genetic hazards as outlined above (Lynch and O'Hely 2001; <br />Ryman and Laikre 1990). Captive propagation and broodstock management plans must address <br />genetic hazards, and provide management strategies to reduce the risk of undesirable or hazardous <br />genetic effects on broodstock and production fish. These genetic hazards are defined as lost <br />genetic variation or altered genetic composition as measured by allelic frequencies, and reduction <br />in fitness of hatchery stocks and offspring as a result of the altered genetic composition (Allendorf <br />and Phelps 1981). <br />Proper application of the plan's guidelines will assist in identifying necessary captive <br />propagation activities, assessing their potential for genetic impacts, and developing and using <br />27