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<br />. <br /> <br />Study Objectives <br /> <br />In order to systematically determine hatchery fish needs, select cultural <br />methods and to find a site for a Colorado River endangered fish hatchery, <br />the follpwing objectives were developed: <br /> <br />1. Estimate fish production needed: Size and number of Colorado River <br />endangered fishes that need to be produced to meet management and research <br />needs in the upper and lower Colorado River basins through 1996. <br /> <br />2. Based on Objective #1, determine the design and size of facilities <br />needed to produce these fish and the best cultural methods to use. <br /> <br />3. Recommend the best sites at which to produce Colorado River endangered <br />fishes. <br /> <br />4. Conduct pre-construction tests and surveys of soil and water on best <br />sites with FWS engineers. <br /> <br />Background <br /> <br />Colorado River endangered fishes have only been cultured since 1973 when <br />adult Colorado squawfish were first taken from the wild for artificial <br />propagation in a hatchery. A few thousand offspring were produced at <br />Willow Beach NFH, Arizona in 1974 (Toney 1974). The methods for spawning, <br />hatching and rearing Colorado squawfish were similar to those used with <br />other warm-water fishes., Warm-water culture methods continue to be used <br />successfully with endangered Colorado River fishes today. Spawning is <br />induced artifically by means of hormonal injection (carp pituitary). <br />Colorado squawfish eggs are either stripped from a female and sperm <br />added from a male to fertilize the e9gs or the fish are returned, after <br />injection, to a spawning pond having a gravel/rock substrate, where <br />spawning occurs naturally (Hamman 1981a). Eggs in spawning ponds hatch <br />naturally, while those stripped from the fish must be tended by hatchery <br />personnel. These eggs are incubated on screens in troughs with flowing <br />water. Treatments are used to control disease. Hatching occurs in 4-6 <br />davs at 684_720F. <br />J <br /> <br />About 3 days after hatching the fry swim to the surface and begin <br />feeding. At this stage they are transferred to rearing ponds where they <br />feed on natural plankton. After several weeks, when the plankton can no <br />longer support the fry, they are given an artificial diet of commercial <br />trout feed. <br /> <br />Cultural methods for humpback chub and bony tail chub are very similar to <br />those for the Colorado squawfish. However, chubs spawn earlier, at <br />lower water temperatures, and grow faster than Colorado squawfish. <br /> <br />At times, survival of eggs and fry has been a problem, particularly with <br />Colorado squawfish (Table 1). Colorado squawfish hatching success at <br />Willow Beach NFH in 1981 ranged from 3 to 90% for different spawns <br /> <br />2 <br />