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Colorado squawfish reproduction is enhanced by high spring <br />flows followed by a rapid warming period sufficient for development <br />needs of eggs and larvae (Haynes et al. 1985). High flows may <br />provide quality spawning substrates by flushing silt from potential <br />spawning substrates (Wick et. al. 1983, Haynes et al. 1984). <br />Colorado squawfish egg survival is greatest at 20 to 22 C in <br />laboratory experiments (Bulkley et al."1982, Marsh 1985). Egg <br />survival is reduced when temperatures depart from this range (Marsh <br />1985). <br />Larval Drift Hypotheses <br />Colorado squawfish larvae appear to drift or move long <br />distances downstream from the areas where they are hatched (Miller <br />et al. 1982c, Wick et al. 1983, Haynes et al. 1985). The larvae are <br />found in drift samples shortly after spawning occurs (Haynes et al. <br />1985). A few-weeks later, peak abundance of the larvae in <br />backwaters occurs up to 177 km (110 mi) downstream from presumed <br />spawning sites (Tyus et al. 1982b). This apparent movement may <br />provide an adaptive advantage by moving 'larvae out of cooler, cobble <br />substrated areas where .spawning occurs, and -into downstream areas <br />where warmer, shallow habitats provide conditions for rapid growth <br />(Tyus 1985b). <br />Not all evidence supports the larval drift hypothesis, and <br />some evidence is open to alternate interpretations. Colorado <br />squawfish larvae may not travel long distances downstream in the <br />Colorado River (Archer et al. 1985). Colorado squawfish larvae may <br />10 <br />