Evaluation of Razorback Sucker and Colorado Squawfish Batch Marking Techniques

Abstract

Abstract Young razorback sucker Xyrauchen texanus (mean total length [TL] = 127 mm) and Colorado squawfish Ptychocheilus lucius (mean TL = 150 mm) were marked by freeze branding and injection of a fluorescent elastomer. The elastomer injection was made at the base of the anal fin and on the operculum (razorback suckers) or lower jaw (Colorado squawfish) and consisted of one of four colors: green, blue, red, or orange. Freeze branding had 99% retention after 15 months for both species. Elastomer recognition was better for Colorado squawfish (mean 74%) than for razorback suckers (mean 60%) after 15 months, and retention at both locations was similar. Red and orange had the best recognition and blue had the poorest. Red and orange elastomer injected in young Colorado squawfish could be detected (95%) for 5 months. One person implanting elastomer at two locations on each fish and one person anesthetizing and handling fish can mark 130–140 fish/h. Approximately three times that number can be freeze-branded per...