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. . 11 Larval Occurrence CRFP studies include the routine sampling of the larval-fish community both within and downstream of the I5-mile reach. During the 3 years of CRFP investigation, 31 larval squawfish were collected from two I5-mile reaches of the Colorado River immediately upstream and downstream of the confluence with the Gunnison River (Table 1). Although the sampling effort was similar in the two river reaches, only 2 (6 percent) of the larvae were collected from the upstream reach. These observations may indicate that most fish were spawned in the downstream reach. However, it is also possible that the larvae were spawned in the upstream reach and drifted downstream to the area where most of the captures were recorded. Postlarval Young-of-Year Occurrence The relative abundance of postlarval young-of-year (YOY) Colorado squawfish in river reaches upstream and downstream from the confluence with the Gunnison River (Table 2) was similar to that for larvae (i.e., all postlarval squawfish were collected from the downstream reach). The catch rate of YOY squawfish warranted classification of the reach immediately downstream from the confl uence of the Gunni son River as a "Major YOY Nursery Area" by the UCRB Biology Subcommittee (UCRB Biology Subcommittee, I984). Non-Spawning Adult Occurrence Almost all of the adult-sized Colorado squawfish collected during spring surveys came from the upstream river reach (Table 3). Although not included in these analyses, many additional squawfish were collected from flooded gravel pit ponds adjacent to the Colorado River. The fact that relatively large numbers of fish were captured in the early spring suggests that adult Colorado squawfish may be using the I5-mile reach as wintering habitat. Importance of the I5-Mi 1 e Reach to Colorado Squawfish The importance of the IS-mile reach from Palisade to the confluence of the Gunnison River must take into account the fact that the fish is currently endangered with extinction and restricted to 25 percent of its original range. The Colorado River subbasin population shows particular signs of being imperilled; catch-per-unit effort rates for larvae, young-of-year and adult Colorado squawfish are significantly less than for the Green River population (UCRB Biology Subcommittee, I984). Additional loss or degradation of remaining habitat will likely exacerbate the problems that the species is having and restrict opportunities for recovery. Field studies conducted over the past several years by FWS (see above) document the use of the IS-mile reach by several life stages of Colorado squawfish (i.e., adults, larvae, postlarval young-of-year). Several factors,