Laserfiche WebLink
<br />preferred boulder substrate that offered cover. Specifically, they occupied <br />velocities of approximately 0.06 m/s near current and remained near the bottom <br />of tanks. In general, Bissonette and Crowl (1995) suggested that age-1 <br />bonytail appear to select localities near moderate velocity, more turbulent <br />areas, while both resting and feeding, always remaining near the substrate. <br />' Their observations are similar to those reported by Vanicek and Kramer (1969) <br />I and Valdez (1985). <br />Feeding <br />Stomachs of adult bonytail indicated that they feed mainly on <br />terrestrial insects, plant debris, and algae. Bonytail were suspected to be <br />mainly surface feeders in runs or glides, whereas roundtail chub feed mainly <br />on aquatic insects and are occasionally piscivorous (Vanicek 1967; Vanicek and <br />Kramer 1969; Minckley 1973). Vanicek and Kramer (1969) found that young Gila <br />stomachs contained chironomids and ephemeroptera larvae. Bissonette and Crowl <br />(1995) found that age-1 bonytail were observed to feed very much like trout in <br />laboratory flumes, occupying a station near the substrate (rather than near <br />surface), near or in the thalweg, passively feeding on drifting material. <br />This change in feeding may indicate an ontogenetic switch in feeding behavior <br />from benthic to more general or pelagic feeders. However, laboratory results <br />did not represent natural allopatric feeding conditions which may also affect <br />the feeding behavior of young fish. <br />Reproduction <br />Vanicek and Kramer (1969) found bonytail in spawning condition after <br />water temperatures reached 18°C on the descending limb of spring peak <br />hydrograph. The most successful spawning occurred during the highest <br /> <br />12 <br />