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<br />63 DEVELOP RAZORBACK BATCH MARKING TECHNIQUES <br /> <br />Individual family lots of razofback suckers are hatched and reared in separate tanks for <br />their first year of life. In their second year, the fish are transferred to outside ponds to <br />make room for the next year's cohort. At this time, we have need to identifY batches of <br />family lots so that several lots can be stocked into the same pond. PIT tags are <br />satisfactory in most respects, except they are too expensive ($5.00 each). An <br />inexpensive batch mark that would last for one or two years would be very helpful. <br />This project concludes in FY96. <br /> <br />Recommendations: I. Freeze branding had excellent retention over one growing <br />season for both razorback sucker and Colofado squawfish. 2. Elastomer retention was <br />.poor for razorback sucker but was satisfactory for Colorado squawfish. 3. Red and <br />orange elastomer had the best recognition of all colors under black light; blue had the <br />poorest. <br /> <br />64 SQUAWFlSH ELECTROFISIDNG INJURY ASSESSMENT <br /> <br />Colorado squawfish are a federally listed endangered species. During sampling to <br />monitor their populations, federal and state scientists often collect these fish using boat <br />electrofishing. Electrofishing works by causing fish within a sufficiently strong <br />electrical field to swim toward the anode; when they get close,' the fish are stunned and <br />easy to capture with dip nets. Recent studies have documented that electro fishing can <br />cause injuries that vary with the electrical waveforms and techniques used. Injuries can <br />include external bruises, hemorrhages, and dislocated or broken vertebrae. Often these <br />are hidden injuries that are only exposed by X-ray or dissection. Since electrofishing is <br />an effective and important sampling tool fOf many fare and endangered fishes, including <br />Colorado squawfish, it is important to identifY any potential harm caused by present <br />electrofishing gear and techniques. <br /> <br />This study will provide a non-lethal, relatively inexpensive preliminary assessment. We <br />will x-ray dorsal and latefal aspects of Colorado squawfish after they are cgllected by <br />electrofishing by U. S. Fish and WLldlife Service, Colorado, or Utah Divisions of <br />Wildlife personnel during Standardized Monitoring to identifY spinal injuries. We will <br />also record conditions including water temperature and conductivity, electrical output <br />(voltage and amperes) and voltage gradient for correlation with observed injuries. If <br />injuries are documented in significant number, we will recommend means for reducing <br />those injuries. <br /> <br />Recommendations: Continue work as scheduled in 1996 <br /> <br />A-3! <br />