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/ ~.. Radiotelemetry of Colorado squawfish A radiotelemetry program was initiated at the Vernal station in March 1980. The objective of this work included an investigation of major movements, habitat preference and spawning of Colorado squawfish. In addition to work done on the Colorado squawfish, observations were also made on a razorback sucker. During the spring of 1980, extensive sampling was conducted in strata E and F in order to collect Colorado squawfish for use in radio- telemetry studies. It is emphasized that these collections were biased in favor of obtaining Colorado squawfish from habitats where they were most abundant. Although cold weather made it difficult to collect fish, the collections began in March so that the fish might recover from the surgery before the spawning season. Collections were initiated using trammel nets and electrofishing gear; however, trammel nets were discontinued because of manpower shortages and a lack of success with them. Early efforts also included the use of larger seines. These efforts were also terminated because of lack of manpower. Colorado squawfish (TL 508-707 mm) and razorback suckers were captured by electrofishing in the Green River. Fish were anesthetized with MS222 and surgically implanted with radiotransmitters immediately after capture. Surgical procedure was similar to Bid good (1980), except for several departures. Sutures were individual (usually five) rather than the continuous suture used by Bidgood and the incision was made laterally, immediately anterior and slightly 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, 1980). Surgical implantation was completed with AVM fish modules (AVM 1979) dipped in melted beeswax. These transmitters (Sm-1) weighed app- roximately llg and are of "padlock" shape. The units are powered by a mercury (HG-630) battery and have a theoretical life of about 215 days. The units transmitted in the 40.660-40.700 MHz frequency range. Radio receiver sets used were Smith-Root RF-40 and SR-40 models. The RF type enables the investigator to identify any particular 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 type antennas 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 (directional) was used only to triangulate fish location. This was done by boat or from shore. It was necessary to use aircraft to keep contact with several fish at one time. The most successful aircraft used were helicopters and a Piper Supercub (the Piper airplane was designed for low altitude and slow flight). The aircraft were operated as slow as practicable at low elevation.