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that razorback suckers may move to spawning areas within the 15-mile reach, then--perhaps like Colorado squawfish--return to feeding and resting areas of relatively small size for the remainder of the year. The two ripe razorback suckers captured in spring 1986 were caught in a gravel-pit pond connected to the river. One was a female captured on 3 June; she had very ripe eggs that could be expressed when slight external pressure was applied. The other was a male captured eight days later, about 30 m from the site of the female; he had thin milt expressable with slight pressure. Again, no larval or YOY razorbacks from our collections have as yet been identified as such. Habitat Use Adult Colorado squawfish Habitat use-by adult squawfish during 1986 and 1987 was determined by measuring depth, velocity, substrate and temperature at the locations of radio-tagged fish, as well as by visually categorizing the habitat type (e.g. pool, eddy, riffle, etc.). In 1987, we also began monitoring water clarity in the 15-mile reach. Habitat Type During runoff in spring, riverside gravel-pit ponds became flooded and accessible to fish from the river; many squawfish moved into these zero- velocity, warm habitats then (Fig. 6). By early July, squawfish had moved from these ponds as the river receded and the ponds once again became isolated from the river. During July-November, use of backwaters greatly diminished and pools and runs were more often used; a few fish were found in riffles and rapids. During November-December squawfish moved to wintering 22