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<br />. <br /> <br />. <br /> <br />IV. Study Area (river miles and sampling dates, if appropriate) <br /> <br />Black Rocks area of the Colorado River, river mile 134 to 136. <br /> <br />V. Study Methods/Approach (Provide a clear description of sampling methods, <br />gear types, numbers and life stages of fish to be collected, statistical <br />analyses to be used, etc.) <br /> <br />Kaeding et al. (1990) and Valdez and Clemmer (1982) monitored radio- <br />equipped humpback chub in Black Rocks for a combined total of four years. <br />Kaeding et al. (1990) also monitored roundtail chub for two of those same <br />years. Kaeding et al. (1990) estimated the spawning period for both <br />humpback chub and round tail chub using a gonadosomatic index (primarily <br />for roundtail chub) and external characters (including ripeness) for <br />three years. This information was related to streamflow as measured at <br />the USGS stream gage at the Utah-Colorado state line. Additional <br />environmental variables are available and will also be related to <br />spawning period. Kaeding et al. (1990) concluded that humpback chub <br />round tail chub both spawned in the Black Rocks area at the same time <br />reported that spawning occurred throughout 1.6-km Black Rocks area. <br />also concluded that there was no spatial separation because they <br />collected running ripe humpback and roundtail chubs from the same trammel <br />net on several occasions. Kaeding et al. (1990) concluded that during <br />years of high runoff, spatial and temporal isolating mechanisms did not <br />exist between the two species. However, temporal separation may occur <br />during years of average or low runoff. <br /> <br />and <br />and <br />They <br /> <br />Because four years of radiotelemetry data already exist for Black Rocks, <br />we do not propose to do additional radiotelemetry during the first year <br />of the study. If rsdiotelemetry data from Westwater Canyon indicates <br />that we need more detailed information from Black Rocks than is already <br />available, we will radio tag humpback chubs during future years of study. <br />Initially we intend to identify the spawning period and estimate <br />reproductive success of humpback chub using a combination of trammel <br />netting and electrofishing for adult chub, and dip netting and seining <br />for larval and post larval chubs. <br /> <br />Assess spawning period: Based on information on spawning time provided <br />by Kaeding et al. (1990), the Black Rocks area will be sampled with <br />trammel nets and electrofishing to follow the annual maturation of <br />humpback chub. The sampling will be done weekly and will begin as the <br />known spawning time approaches. Sampling will include the entire 1.6-km <br />section of Black Rocks. Because environmental conditions will vary from <br />year to year, the exact timing for initiation of sampling cannot be <br />known, but it will probably begin in early to mid May and will continue <br />through early to mid June. The reproductiye condition of all captured <br />chubs will be determined using external characteristics. As spawning <br />time approaches, indicated by the capture of ripe male chubs, sampling <br />will be intensified to attempt to narrow down the actual spawning <br />locations and the spawning period. Because males can be ripe for a long <br />period, ripe females are the best indicator of spawning period and <br />location. However, the capture of a ripe female is difficult. Of the <br />597 chubs handled by Kaeding et al.(1990). only 14 were ripe females. <br /> <br />Aspinall-Gj2 <br />