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<br />. <br /> <br />Jud9ing from the pond culture of other minnow species (Dobie 1956) a <br />production of 50,000 fingerlings (3 inch) per acre with artificial <br />feeding would be a reasonable production figure for humpback and bony- <br />tail chub. Colorado squawfish are piscivorous, like walleye, and a <br />production of 20,000-30,000, 3-i nch fingerl ings per acre with artificial <br />feeding would be a more reasonable estimate for this species. <br /> <br />Therefore, to produce the 500,000, 3-inch fingerlings (250,000 Colorado <br />squawfish, 125,000 bony tail chub, and 125,000 humpback chub) called for <br />in the CP would require a minimum of 20 one-acre production ponds plus 5 <br />one-acre ponds for broodstock production. Also, 10 small earthen ponds <br />(0.1-0.25 acres) would be needed for holding small lots of fish, by'ood- <br />stock and for experiments. In addition, six raceways (6' x 60') would <br />be needed to hold fish prior to shipment and to hold and/or quarantine <br />i ncomi ng fi sh. <br /> <br />A holding house would be needed to hatch eggs, start fry and hold and <br />inventory fish as they come out of the ponds. The holding house should <br />have 16 tanks, an egg incubation room, and a small laboratory for <br />disease diagnosis and biological studies. Beyond these needs, standards <br />for pond hatchery facilities should be consulted (Piper et al. 1982 and <br />USDI 1969). <br /> <br />RACEWAY CULTURE: Raceway culture is a workable alternative to pond <br />culture and has some advantages. As Willow Beach NFH and others have <br />shown repeatedly, Colorado River endangered fishes can be grown in <br />raceways on trout food. Percent survival from fry to fingerlings has <br />been higher in raceways than in ponds (example Willow Beach NFH vs <br />Dexter NFH). Furthermore, with intensive culture, handling and management <br />of fish is more efficient. <br /> <br />Calculations were made to illustrate what raceway culture would entail <br />(Tables 4, 5, 6). This information presented in the raceway tables is <br />based upon a constant temperature of 770F and 7 ppm oxygen. The flows <br />given in these tables assume reuse of the water. Raceways arranged in <br />series would permit the water to be reaerated as it drops from one <br />raceway to another. The amount of oxygen added would depend on the head <br />available, the number of times the water was reused, and other conditions. <br /> <br />For the best results, an additional supply of cool water should be <br />desirable. Then, rate of growth could be controlled to produce fish the <br />right size at the right time. This could be accomplished in two ways: <br />1) by using a cool spring or well or, 2) by using cooling ponds to lower <br />water temperature. <br /> <br />The densities of fish given ln Tables 4 thru 6 are conservative, since <br />well-fed channel catfish were used as a model. Intensive raceway <br />culture of Colorado River endangered fishes needs to be carefully studied <br />before precise predictions can.be made. <br /> <br />10 <br />