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-'J -- '~ ATTACHMENT TASK DESCRIPTIONS FY92 BLACK ROCKS CANYON TASK I. ESTIMATE SPAWNIHG PERIOD, REPRODUCTIVE SUCCESS, AND POPtJLM:IOH SIZE OF BUMPBAClt CHUBS IH BLAClt ROCltS Kaeding et al. (1990) and Valdez and Clemmer (1982) monitored radio-equipped humpback chub in Black Rocks for a combined total of four years. Kaeding et al. (1990) also monitored roundtail chub for two of those same years. Kaeding et a1. (1990) estimated the spawning period for both humpback chub and roundtail chub using a gonadosomatic index (primarily for roundtail chub) and external charactere (including ripeness) for three years. This information was related to streamflow as measured at the USGS stream gage at the Utah-Colorado etate line. Additional environmental variables are available and will also be related to spawning period. Kaeding et a1. (1990) concluded that humpback chub and roundtail chub both epawned in the Black Rocks area at the same time and reported that spawning occurred throughout 1.6-km Black Rocks area. They also concluded that there was no spatial separation because they collected running ripe humpback and roundtail chubs from the same trammel net on several occasions. Kaeding et al. (1990) concluded that during years of high runoff, spatial and temporal isolating mechanisms did not exist between the two species. However, temporal separation may occur during years of average or low runoff. Because four years of radiotelemetry data already exist for Black Rocks, we do not propose to do additional radiotelemetry during the first year of the study. If radiotelemetry data from Westwater Canyon indicates that we need more detailed information from Black Rocks than is already available, we will radio tag humpback chubs during future years of study. Initially we intend to identify the spawning period and estimate reproductive success of humpback chub using a combination of trammel netting and electrofishing for adult chub, and dip netting and seining for larval and post larval chubs. Task lA' Assess spawning period. Based on information on spawning time provided by Kaeding et al. (1990), the Black Rocks area will be sampled with trammel nets and electrofishing to follow the annual maturation of humpback chub. The sampling will be done weekly and will begin as the known spawning time approaches. sampling will include the entire 1.6-km section of Black Rocks. Because environmental conditions will vary from year to year, the exact timing for initiation of sampling cannot be known, but it will probably begin in early to mid May and will continue through early to mid June. The reproductive condition of all captured chubs will be determined using external characteristics. As spawning time approaches, indicated by the capture of ripe male chubs, sampling will be intensified to attempt to narrow down the actual spawning locations and the spawning period. Because males can be ripe for a long period, ripe females are the best indicator of spawning period and location. However, the capture of a ripe female is difficult. Of the 597 chubs handled by Kaeding et al.(1990), only 14 were ripe females. sampling for larval chubs will begin when it appears that spawning has occurred or is about to occur. All adult and subadult chubs collected during this portion of the study will be treated according to the Interagency Standardized Monitoring Program protocol and will be equipped with a PIT tag before release. Task lB' Assess spawning habitat. If a specific spawning site is located, the area will be carefully described and mapped using the techniques described for Westwater Canyon. As we accumulate additional years of data, the relationship between streamflow at the time of spawning and the amount of available spawning habitat will be described.