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Razorback sucker Xyrauchen texanus Broodstock A joint Fede.al-State recovery team, under the chairmanship of Mr. Kob~tich, collected forty adult suckers near Cottonwood Cove, Lake Mohave, on March 27, 1974. Water temperature in the lake varied with depth. Average was around 670F. Some eggs were stripped at Cottonwood Cove. Additional eggs were ob~ained after the adults had been moved to Willow Beach. There was no attempt to determine the number of eggs per female, as the fish were captured while in the process of spawning. Thirty-two of the adults were transferred to the Arizona State Hatchery at Page Springs on May 7, 1974. The eight remaining adults were sacrificed for disease inspection. Eqq Care We made no attempt to.accurately enumerate the number of eggs obtained. A rough estimate would be five to ten thousand. Egg size varied from 2.1 to 3.2 millimeters in diameter. Two methods of incubation were tried. The one previously described, and jar incubation with a constant flow of 530F. river water. Mortality in the jar ~Jas high from the beginning, possibly due to the low water temperature or too much_agitation. The dead eggs became fungused, and all were dead at eight days. . In contrast, mortality on the tray in the tank was very low. The eggs hatched on the fifth and sixth days. Estimated hatch was 95 percent. Water temperature in the tank was 580F. on the first day, and varied from 600F. to 630F. from the second day. Fry Care Upon hatching, and for six days, the fry had very little, if Qny, pigment, and were very difficult to distinguish. Length at hatching was five to seven millimeters. On the sixth day after hatching, the eyes were pigmented, and the fry began to s~Ji m to the surface. . Sma 11 amounts of baby food, strai ned beef liver,.was fed four or five times daily. The fry fed actively on this for two weeks. After three weeks in the hatchery, including the egg stage, 3,259 fry were hand-counted to an outdoor raceway on April 17, 1974. The raceway i.s eight feet wide by one hundred feet long, with a water depth of thirty inches. .. Zooplankton are numerous. Predominately Cladocera and blackfly larvae. The fry literally gorged themselves and grew to 35 millimeters total length .by the end of Hay. From this time, there has been a considerable size variation. A representative sample would be difficult to obtain \oJithout cap- turing a large number of the fingerlings. Their small size and heavy algae growth renders this impractical. As of June 30th, there were some specimens over three inches in total length. The average length somewhere around two and one half inches, or sixty to seventy millimeters. 256