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distribution. A standardized spring sampling program was initiated in the Green River in 1984. Adult and juvenile Colorado squawfish class- ifications were defined as fish greater than8mm TL and between 59 mm a~_. respectively. .. Substantial efforts were devoted each spring from March through May to /~ capture adult Colorado squawfish for implantation with radio trans- mitters. Both electrofishing and trammel or gill nets were utilized but electrofishing was the most effective and primary gear used in the Green River with nets being more effective and providing the most catch informa tion in the Colorado River. Records were kept of all captures with associated information on location, TL and weights. A serially numbered Carlin dangler tag of different color for each river system was attached to each Colorado squawf1sh greater than 300 mm TL. Also, efforts were frequently made to capture adult fish in areas where radiotelemetered fish appeared to congregate in an attempt to confirm the presence of gravid adults. Rad 10 teleme try The radiotelemetry program was instituted to assist in locating spawning areas, follow migratory behavior and to deteDnine habitat preferences. From 15 to 30 adult Colorado squawfish of 500 mm TL or greater were implanted annually in each of the two major river systems. Implantation generally took place in April and May using primarily AVM and Smith-Root transmitters weighing between 9 and 20g and transmitting in the 40 MHz range with varied pulse rates to permit differentiation of individual fish. Search operations were conducted primarily with boats but aerial searches were somet:1mes conducted in an attempt to locate lost trans- mitters. Searches were on approximately a two-week rotation until spawning season approached when search ope.rations were intensified to a weekly and sometimes daily schedule. Se.arch and tracking receivers were primarily Smith-Root units equipped with directional and non-directional antennas depending on the type of activ! ty. Once located, directional antennas were used to pinpoint as closely as poSSible the location of 5