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1 j <br />after spawning apparently occurs. Osmundson and Kaeding (1990) reconciled <br />this apparent conflict by hypothesizing that razorbacks historically spawned <br />in flooded areas out of the main channel. These flooded areas are warmed by <br />sunlight and ambient air temperature, and are often much warmer than the main <br />channel. Osmundson and Kaeding (1990) reported temperatures of 22 °C in off- <br />channel habitats when main-channel temperature was 13 °C. If their hypothesis <br />is correct, reduced spring flows could account for the lack of reproductive <br />success by razorback sucker. Unfortunately, the effect of reduced spring <br />runoff has been compounded by dike building and channelization which has <br />reduced the number of lowland areas available for flooding, and by the <br />occurrence of large numbers of introduced fishes in the remaining flooded <br />habitats. Predation on razorback sucker eggs and larvae by introduced fishes <br />may also contribute to reproductive failure (Minckley 1983; Tyus 1987). <br />Suitable habitat for reintroduction of razorbacks into the Gunnison River <br />exists near Delta (Wick, personal communication) if adequate streamflows can <br />be restored. <br />Humpback chub <br />Humpback chub spawn during spring runoff (Valdez and Clemmer 1982; <br />Kaeding et al. 1990), so it is likely that runoff level affects reproductive <br />success of the species. However, the relationship has not yet been examined. <br />Eight years of river-wide larval data are available and could be examined to <br />estimate the relative abundance of young-of-the year humpback chub. Reliable <br />identification of larval humpback chub was not possible until recently when <br />Muth (1990) completed a key describing larvae of bonytail, roundtail chub, and <br />humpback chub. However, it is not clear whether the river-wide data will be <br />28 <br />