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. DRAFT 3.1.2 Radiotelemetry . 3.1.2.1 Radiotransmitters and Receivers . Radiotelemetry was used to locate and follow movements of adul t Colorado squawfish and razorback suckers. Twenty radiotransmitters (fish modules), were provided by FWS during year 1; 10 manufactured by Smith-Root (P-40) and 10 manufactured by AVM (SM-1). The Smith-Root and AVM transmitters were powered by lithium and mercury batteries, respectively, each with a 12 to 14-month life expectancy. For year 2, 20 Smith-Root (P-40) radiotransmitters were purchased by BIOjWEST. . All of the transmitters used in this investigation operated within the 40.660 to 40.700 MHz range, with pulsed transmission rates of 40 to 80 pulses per minute. All transmitters were tested for pulse and frequency upon receipt from the factory, and each was dipped in melted beeswax prior to implantation. Pulse and frequency were rechecked prior to and immediately following implantation to insure that the transmitters were performing according to factory specifications. . Smith-Root search (SR-40) and standard tracking (RF-40) receivers were provided by FWS for use in this study. An Advanced Telemetry Systems (ATS) programable scanning receiver was also provided by BOR. Larsen Kulrod NMO-40 whip omnidirectional antennas and Smith-Root loop directional antennas were used with the receiving units. . 3.1.2.2 SUrgical Implant Procedures . The radiotransmi tters were implanted surgically according to the techniques described by Tyus (1982). Fish were anesthetized with tricaine methanosulfate (MS-222) in a portable live well. A fish was determined to be sufficiently anesthetized when, within 1-2 minutes, it could no longer maintain equilibrium in the live well. . Surgery was performed by placing the fish on a measuring board or specially designed cradle placed atop the live well. One person held the fish firmly in position while another continuously bathed the gills with anesthetic water to a point about midway through the surgery at which time fresh water was used to minimize the effect of the anesthsia. A small incision (2.5 - 3.0 cm long) was made anterior and slightly dorsal to the insertion of the left pelvic fin. The transmitter was inserted toward the posterior end of the fish so it came to rest on the pelvic girdle within the parietal cavity. The incision was closed with four to eight sutures using 3-0 Ethilon™ black monofilament nylon with FS-l cutting needle. Each fish was then observed in a live well or recovery pen in the river for a period of up to 1 hour, until it was actively swimming and was then released. . . All adult Colorado squawfish and razorback suckers were weighed, measured, and equipped with a uniquely-numbered orange Carlin tag attached to the base of the dorsal fin. previously tagged fish were recorded as recaptures and the tag replaced only if the original attachment thread appeared frayed. Only squawfish 530 rom total length (TL) or larger were implanted with radiotransmitters, 7 .