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<br />. ;'-3 JS '3{l <br /> <br />.....-- <br />L' ..:. <br /> <br />4. Que.tion: How do discharge fluctuations, mlnlmum <br />discharges and rates of change of fluctuating discharges affect <br />trout? <br /> <br />8.-4.1. There is no significant relationship between the <br />rate of stranding of trout and the ~agnitude of discharge <br />fluctuations, and minimum discharges, or the rate of Change of <br />fluctuating discharges. <br /> <br />Justification: The tailwater reach below Glen Canyon Dam is <br />considered a blue ribbon trout fishery. The fiShing public <br />utilizing this resource has expressed a desire for the <br />opportunity to catch both large and naturally reproduced <br />trout. Regulatory changes are being instituted to increase <br />the probability of catching larger fish, but the degree of <br />successful natural reproduction is believed to be limited by <br />dam operations. Spawning trout often develop their redds in <br />gravels that are inundated and then subsequently exposed <br />during each fluctuating flow cycle. Spawning trout which <br />attempt to remain with their redds can become stranded at <br />low water and suffer mortality. In addition, the redds may <br />be desiccated and emergent alevins sutfer high mortality as <br />was shown experimentally during GeES Phase I. In downstream <br />areas, flows from discharge tluctuations having low minima <br />may also limit trout access to tributaries which serve as <br />important sites of natural reproduction (see also H.-S.l). <br /> <br />Intorastion .eeds: Data will be collected on the amount of <br />stranding under various diSCharge regimes (see H,-l.l) <br />between Lee's Ferry and Glen canyon Dam. This will be <br />primarily during the spawning season. Length, weight, se~, <br />reproductive stage and fecundity will be determined tor a <br />representative sample ot the fish. Stranding will be <br />determined relative to location, area, time, and number of <br />fish. Stranding areas will also be sampled for exposed <br />redds in order to develop a relationship between standing <br />and spawning. Limnological variables, including water <br />temperature, dissolved oxygen, pH, and conductivity will be <br />.easured to determine correlations with observed <br />IIOrtal1ties. <br /> <br />The followinq secondary hypotheses will be tested using the <br />research proqram established for H.-4.l. <br /> <br />6o-4.1a. There is no significant relationship between the <br />rate of stranding of trout and the magnitude ot daily diSCharge <br />fluctuations. <br /> <br />H.-4.lb. There is no significant relationship between the <br />rate of stranding of trout and the magnitUde of daily minimum <br /> <br />7 <br />