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Biological considerations The primary concerns with capture and grow out of wild larval (or age-O) fish appear to involve issues related to ethology (behavior) rather than to genetics. Juvenile experience (or lack thereof) can have profound influence on their success in the wild (Curio 1996, Maynard et al. 1995, Fleming et al. 1997). There are a multitude of mechanisms that can impair survivorship, including lack of anti-predator responses, lack of knowledge about feeding and food types, tendencies to be excessively active and aggressive, characteristic drops in condition factor after release, and lack of abilities to home to natal areas or knowledge of migratory routes. In addition to behavioral concerns, some potential exists for a form of domestication to occur. It is sometimes mistakenly viewed that domestication selection can be avoided if there is no mortality in culture (Waples 1999). However, fish held in captivity will have natural selection regimes relaxed, which can lead to problems with domestication (Busack and Currens 1995, Waples 1999, Brown and Day 2002). For instance, mortality of humpback chub in the wild occurs, meaning that wild selection is occurring (surviving floods, predation, disease, etc.). By transferring fish into a hatchery environment during this period of their life history, this wild selection is removed. Temporary relaxation of wild selection may not lead to genetic change within the captive population, provided hatchery mortality is kept to zero, but it does lead to genetic change compared with the high mortality in the early life history stages in wild populations (Waples 1999). Some level of genetic change relative to the natural population cannot be avoided in a cultured population (Waples 1999). Therefore, we suggest that it is important to reduce (to the maximum extent possible) the time that fish are held in captivity. Another important goal is to minimize post-release mortality. Poor survival of hatchery- reared fish is a major concern, and greatly reduces the ability of using hatchery stocks to supplement wild production, whether for commercial or conservation purposes (Maynard et al. 1995, Olla et al. 1988, Brown and Day 2002). Generally, larger fish have a higher survival rate (Brown and Day 2002). All factors being equal, one might assume that survival of 200 mm fish would be greater than survival of 150 mm fish. However, increased time spent under hatchery regimes leads to behavioral issues of fish. Even under optimal conditions, fish will be held under unnatural conditions for a substantial portion of their lives (- 1 year or more). This will have impacts on anti- predator responses, feeding ability and possibly other factors related to migration and spawning behavior (Paszkowski and Olla 1985, Usher et al. 1991, Howell 1994, Brown and Laland 2001, Brown and Day 2002). What size fish should be collected, how, from where, and when? A basic premise in fisheries ecology is that survival rates increase with age (e.g., Table 1), and that removal of individuals from a population should be expected to have the least impact upon the population at increasingly younger life stages. For example, 25