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uOti581 33 Biological Resources 2 From Flannelmouth Sucker Management Objective IN 1. Establish whether Flannelmouth Suckers/native fish are actually spawning in the mainstem Colorado River within Glen Canyon under current conditions. If spawning occurs, do any eggs hatch or larvae survive? Determine the current and past (before Glen Canyon Dam) importance of mainstem Glen Canyon spawning habitat (in relationship to tributary spawning). IN 2. Determine the origin of adult Flannelmouth Suckers/native fish that are attempting to spawn in the mainstem Colorado River within Glen Canyon? Are the old pre-dam adults? Are the post-dam adults from the tributaries, i.e., Paria River, that find certain mainstem habitat factors preferable? Are they mainstem adults from the Grand Canyon? IN 3. Determine the location of all spawning beds within Glen Canyon (related to flows) and summarize the important characteristics. Determine the relative importance of Glen Canyon habitat in relationship to other mainstem habitat within Grand Canyon. IN 4. Specifically determine the cause(s) for mainstem spawning failure within Glen Canyon: a. Eggs not deposited, or if deposited not viable because of low water temperature or fluctuating flows, i.e., drying of spawning beds or removal of eggs by strong currents. b. Fertile eggs deposited and hatch but larvae can't grow because of limited or no nursery habitat for food and shelter (again, due to cold temperatures and fluctuating flows). c. Eggs laid and hatch and some survive and move downstream to warmer water and return much later to spawn. IN 5. Describe the specific role of flow levels and fluctuations on reproduction and survival of eggs, larvae, young-of-year, and adults. Specifically, determine the availability of moderate near-shore habitat that might be used by larvae, young-of-year, or adults. Revised 6-10-98