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-which life r<:quirements of the target species :are well understood and are provided at the -sites proposed for stocking. Sites must be ~onitored to determine this. Habitat loss was -presumably the prime factor associated with .extirpation of squawfish in the lower basin, -and if habitats have not improved, reintroduc- tions are at best a stopgap measure (Rinne et ale 1986). Fish culture has dominated fishery science in the United States for at least fifty years and has been regarded (by some) as a panacea to stop the loss of fisheries. It was not until the decade 1930-1940 that research highlighted the need for habitat protection and manage- ment (Radonski and Martin 1986). In the past, fish culture was not directed at restoring endangered fishes. Rather, it was directed at maintaining fisheries for sport or commercial harvest. There are many questions to be answered regarding use of hatcheries and stocking in management for recovery of wild populations before the methodology is used in accelerated or broadly applied efforts. "Without habitat maintenance or improve- ment, hatcheries should be considered tempo- rary refuges for genetic material and research facilities for laboratory studies. The Colorado squawfish is a case in point. It has a complex life cycle in which there are spatial separations of life-history stages, in- corporation of energetically costly migra- tions, and no doubt other, as yet unknown, components. If management for recovery is to succeed, these and other life-history attributes must be considered in the hatchery/stocking program. Some individuals migrate down- stream to reach spawning grounds, and others migrate upstream to reach the same place (Tyus 1985, 1990). This phenomenon could be based on environmental cues (e.g., through olfaction or other means), or it might be under genetic control (Bowler 1975). Imprint- ing or other forms of fixation of cues may be disrupted under hatchery conditions, and a The Colorado Squawfish 397 genetic basis could preclude successful estab- lishment of a population. These migration behaviors suggest mech- anisms for which we only have hypotheses. Ideally, areas proposed for reintroductions should be evaluated and ranked for availabil- ity of suitable habitat for all life stages. For example, shallow nursery habitat should be present below areas suitable for spawning, and availability of both spawning and nursery areas should coincide with proper water tem- peratures and discharges. Non-native Species and Sport Fishing Impacts of introduced fishes on native faunas (reviewed by J. N. Taylor et al. 1984) are sel- dom understood and have been largely in- ferred from major alterations of species com- position. Competition (Connell 1983; Ross 1986) between native and introduced forms is difficult to document experimentally, and perhaps impossible to prove in nature. Direct effects of fish introductions on native fishes were categorized and reviewed by Moyle et al. (1986) as follows: elimination, reduced growth and survival, changes in community structure, and no effect. They stressed that many fishes are introduced into habitats that are already changing due to the impacts of hu- mans, making it difficult to determine if habitat change, competition, both, or other factors are responsible for decline of the na- tive fauna. This already complex issue is further con- founded by introductions into waters in which species interactions were not well un- derstood anyway. Stocking of new species into an area to promote sport fishing has often created more problems than it solved, mostly because methods for predicting outcomes are few (Li and Moyle 1981). Stocking of non- native warm-water species has been reduced in recent years, and under the RIP will not occur in watersheds occupied by Colorado squawfish unless it would not interfere with l1~ :11 , II' Illl ',k! : Il"r1 , \ < ! ( 'I II Ii l .1:1 1,)1 Ii , I i !