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., ~ - 2 - The purpose of this radiotracking program and random sampling is to identify spawning times and sites used by humpback chubs in Westwater Canyon. We hypothesize that the fish spawn in concentrations over cobble/gravel bars that occur in few locations in the canyon. If this is the case, it is reasonable to expect close association of several radiotagged fish in one or more such areas. Once a spawning site is identified and confirmed by the presence of expressible gametes from both males and females, (possibly eggs and/or larvae), water depth, velocity, substrate type, and temperature will be measured and assessed. Also, the site will be mapped in detail, including associated habitats, shoreline features, and instream cover. That same area will be mapped again at different flows, as discussed in the section on flow-spawning habitat relationships. All endangered fish captured during this investigation will be treated according to the current USFWS and UDWR protocol; they will be measured, weighed, and equipped with a uniquely-coded PIT tag. All humpback chub will be photographed on a "chub board" divided into 1-CllI grids. subtask lC: Seine Age-a. Westwater Canyon will be seined on a regular basis through summer and fall to follow the strength of the cohort as well as length of individuals. Low velocity areas will be seined and the fish sorted, released and identified when possible. Specimens that are difficult to identify will be sent to LFL. Subtask 1D: Map Habitat.s. spawning habitat will be assessed in Westwater Canyon using aerial mapping and quantitative measurements of habitat parameters; i.e. depth, velocity, substrate, cover. The habitat mapping will be done on aerial photographs as base maps. One photo series should provide a reliable base for habitat mapping, since the channel in Westwater Canyon is not expected to change appreciably because of the geologic nature of the hard pre-cambrian igneous basalt (gneiss and schist). Only the 20 km between Wild Horse Cabin (RM 124) and Big Hole (RM 116) will be photographed. It is estimated that several photo lines will be required because of the meandering nature of the river, but we believe that five photos per mile of river should provide sufficient coverage for mapping. Selected aerial photographs will be enlarged to a scale of 1:2000 to be used as base maps. It should be made clear at this point that the aerial photographs are to be used as base maps and not for direct measurement of habitat area. The area of each habitat will be determined by an observer standing on shore, and visually delineating each on a sheet of acetate overlayed on the aerial photograph. Using permanent features as reference points, such as boulders, trees, logs, and shoreline structure, the existing water line will first be hand sketched. Then, with the aid of these permanent reference points, each habitat will be sketched on the acetate overlay, using a specific set of criteria to describe each habitat type, i.e. backwaters, eddies, pools, runs, riffles. Westwater Canyon is an ideal area for this technique, since the high canyon walls allow for viewing the river from a high point and for seeing the different habitat types more readily. The habitat mapping during the first year of the study will focus on those areas in Westwater Canyon suspected as spawning sites. These presently include cobble/gravel bars at RM 124 (below Wild Horse Cabin), RM 121.8 (above Cougar Bar), and RM 120.5 (above the Little Dolores River). Once spawning sites and the associated nursery areas are identified and confirmed, mapping will be done concentrated in these areas.