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dorsal to the insertion of the right pelvic fin. Suture knots were coated with "Krazy Glue" (Bill Loudemilk, letter to the U.S. Fish and Wildlife Service, March 27, 198~.~). Surgical implantation was completed with AVM fish modules (AVM 1979) dipped in melted beeswax. These transmitters (Sm-1) weigh approximately .!! g and are of "padlock" shape. The units are pow- ered by a mercury (Hg-6~~) battery and have a theoretical life of about 215 days. The units transmitted in the 40.660-40.700 !~IHz fre- quency range. Radio receiver sets used were Smith-Root RF 40 and SR 40 types. The RF type enables the investigator to identify ;any particu- lar frequency transmitted in the 40 MHz range. The SR receiver is a "search" type and will pick-up all emitted frequencies in the range. Omni-directional and pin-pointing antennae were employed. A Larson-Kulrod whip antenna was used to search for implanted fish. This antenna was mounted on a 20 cm square steel plate elevated about 4 m above the water when mounted on a boat, or mounted directly to an air- plane wing strut. The loop antenna was used only to triangulate fish location. This was done by boat or from shore. During 1980, it was necessary to use aircraft to keep contact with several fish at one time. The most successful aircraft used was a Piper Supercub operated by the U.S. Fish & l~Jildlife Service. This airplane was designed for low altitude and slow flight. The aircraft ,was operated at about 150 m and 115 kph. Water conductivities-and temperature were measured with a Yellow Springs Model 33 meter. Conductivity readings were reported in micromhos per centimeter (,~ mho). Temperature was reported in decrees Centigrade. RESULTS AND DISCUSSION The radiotelemetry program was initiated March 1980 witlh efforts to capture fish and test equipment. The first Colorado squawfish of suit- able size was captured April 3. This fish was in poor condition when captured but was implanted, held 12 days and released to aid the program in testing equipment and determining if successful radioteleimetry was possible. Previous studies both theoretical (Sinning 1979) and applied (Holden and Selby 1978)- indicated radiotracking in the Green River might be difficult because of high water conductivity and failure of radio- telemetric gear. However, it was possible to track this fish and to re- cover it three days later (after tracking it about 24 km). The fish was then held and treated with antibiotic injections. Success in following the first implanted fish was greater than anti- cipated. We then implanted modules in five more Colorado squawfish and one razorback sucker. Table 1 presents information on the capture, re- lease and major movements of all radiotelemetered fishes studied in 1980. Four Colorado squawfish were followed over four months (Table 1, fish No..'s 2-5). These fish displayed two different types of behavior: