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i ~, The radiotelemetry program utilized two different methods for recording information about habitat preferences and movement. Long distance movement was determined by attempting to locate all radio tagged fish on a 1-2 day interval. The location of a fish was recorded on a one-time basis when encountered. In order to obtain more specific information on movement and habitat preferences, a diel sampling pro- cedure was employed. This sampling procedure consisted of observations made continuously over a 24 hour basis as follows: 1. The day was divided into three, eight-hour periods and one selected at random. A fish was then observed during this period, with depth, velocity and substrate determinations made every 15 minutes. Habitat measurements were not recorded unless fish were stationary for 30 minutes. 2. After a fish had been monitored for three, 8-hour periods, the fish with the next tag number was then selected for study. Habitat Preference and Taxonomy of Gila spp. Gila spp. (including the humpback chub, Gila cypha, and bonytail chub, Gila ele ans) were extremely rare in collections made the first year of study. Therefore, a special sampling effort for collection of Gila spp. was undertaken in Gray Canyon of the Green River September 27, 1980, and April 23, June 6, July 10 and September 27, 1981 with major emphasis on collection of bonytail chub. This site was selected after several Gila spp. previously collected here were tentatively identified as humpback and bonytail chub. Based on all other areas sampled, it was judged to be the best location for humpback and bonytail chubs in the Green River system. Objectives of these collections were to obtain habitat information and also to provide bonytail chub for possible hatchery propagation. Fish were collected with 150' multifilament trammel nets, multi- filament gill nets and seines. -Sampling was conducted within a 0.1 mile river reach over a 4-day duration. However, because of manpower limit- ations, continuous 24-hour sampling over the 4 days was impossible and a sampling design was initiated. A 24-hour period was divided into three sub-periods, 2400-0800, 0800-1600, and 1600-2400. Sampling alternated between sub-periods. For example, sampling was conducted for an 8-hour sub-period with a subsequent 8-hour non-sampling sub-period followed by another 8-hour sampling sub- period and so on. This allowed every sub-period to be sampled at least twice over the four days. The first sub-period to be sampled was determined when the sampling team arrived at the sampling site. Seven sites encompassing three habitat types (eddy, run and back- water) were selected for seining. Five sites, all eddy habitats, were selected for trammel and gill netting. All sampling sites were re- plicated during the period sampled. Trammel and gill nets were checked once every 2-3 hours. Seining was conducted twice during a sub-period, but was terminated after the first day because of a manpower shortage.