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relevant: 1) long term conservation of genetic variability, and 2) captive breeding for release back into the wild. Generally, the long term conservation of genetic variability applies to a species whose wild habitat may be lost and whose whole future may depend on captive maintenance. For humpback chub, although large portions of habitat have been altered or lost, untested options still remain for improving degraded habitat. Nevertheless, some may view that a refugium is necessary in the event of catastrophic loss. This view should include the conservation and retention of maximum genetic variability. In the case of the second objective (captive breeding for release into the wild), it is important to consider the likelihood for future reintroduction (Seal 1986). If a broodstock is to be developed, several. considerations must be faced. First, how soon is reintroduction into the wild to be expected? The longer fish are held in captivity (e.g., especially in terms of generations), the more likely that divergence from the wild population will occur within the captive population via processes of inbreeding, drift, domestication, etc. This implies reintroduction in the near future. Second, once broodstock and supportive stocking activities are initiated, it is critical that these activities are long-term commitments. This is generally because carrying capacity conditions for the species in decline have not been rectified. As a result, the demographic boost achieved by supportive breeding can be short term, and followed by collapse to pre-stocking levels. Biological concerns The literature is replete with warnings concerning the pitfalls of captive breeding programs (e.g., Waples and Do 1994, Busack and Currens 1995, Philippart 1995, Utter 1998, Ford 2002). Limitations of captive breeding include an array of genetic problems, difficulties in achieving self-sustaining captive populations, failure to breed well in confinement, inability to achieve successful reintroduction back into the wild, problems with domestication (i.e., loss of wild traits), disease, high financial costs, and concern for administrative continuity associated with developing and maintaining a proper broodstock facility (Snyder et al. 1996). Captive broodstock activities can present a suite of risks to the wild population that must be considered in order to prevent costly or irrevocable mistakes. One of the main concerns is that supportive breeding via the use of captive broodstocks can pose genetic risks (or hazards) to wild populations (Ryman and Laikre 1991, Busack and Currens 1995, Lynch and O'Hely 2001, Ford 2002). First, there could be risk of artificial introgression (for instance, introducing genes from other humpback chub populations outside Grand Canyon or from congenerics). Potential loss of among population variability should be a major concern (Busack and Currens 1995, Flagg et al. 1995), and in order to avoid artificial introgression, brood stock should be obtained from the population into which their offspring will be released (Krueger et al. 1981, Hindar et al. 1991, Ryman et al. 1995). This factor holds implications if brood stock activities are coordinated using other populations of humpback chub from the Upper Basin, as well as 12