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<br />the anesthetic Tricaine1 (tricaine-methanesulfonate) with a dose of 200 mg/L via a <br /> <br />treatment bath. The dilute solution was buffered with sodium bicarbonate (NaHC02) <br /> <br />from baking soda to reduce respiratory stress and decrease physiological side effects <br /> <br />of lowered blood pH caused by acidity of Tricaine (Summerfelt and Smith 1990). <br /> <br /> <br />Approximately 200-250 mg NaHC02 per 100 mg Tricaine were added to obtain a pH <br /> <br />similar to river water. Water was refreshed and treated as necessary to maintain good <br /> <br />water quality. Fish were considered anesthetized when opercular rate (respiration) <br /> <br />slowed, and they lost equilibrium, muscle tone, and reactivity to external stimuli. If a <br /> <br />fish experienced an anesthetic overdose, evidenced by lack of opercular movement, <br /> <br />procedures were stopped and the fish was revived immediately in fresh water. <br /> <br />Each fish was measured for total length, weighed, examined for external injuries, <br /> <br />marked with a PIT tag, and x-rayed. Photographs were taken of their left, right, dorsal, <br /> <br />and ventral aspects. <br /> <br />After the x-ray procedure, fish were returned to the holding tank and recovery <br /> <br />was identified when the fish regained equilibrium. Fish were held an additional 15 <br /> <br />minutes after they regained equilibrium and muscular control and were released at site <br /> <br />of capture as soon as possible to reduce captivity stress. The goal was to perform all <br /> <br />procedures and release the fish within 1 hour of capture. <br /> <br />Radiographs of fish were made with a portable, veterinary x-ray unit (MinXrayTM <br /> <br />Model X750-G) set up on shore near the capture site. A standard operating procedure <br /> <br />'Tricaine is the generic term for Finquel™ (often called by its trade name: MS-222™) which is a <br />formulation of Tricaine Methanesulfonate registered with the U. S. Food and Drug Administration by Ft. <br />Dodge Laboratories, Ft, Dodge, Iowa. <br /> <br />4 <br />