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. In the LCRB, Dexter NFH projects a need to increase their production of Colorado River endangered fishes from 200,000 in 1983 to 800,000 in 1986 (Table 3). Clearly, Region 2 intends to produce most of the fish needed in the LCRB and may be able to supply some of the fish needed in the UCRB as well. Of these, only 100,000 Colorado squawfish per year have been requested by Region 6, and then only through 1984. Production of humpback chub was not included in Dexter's anticipated production figures (Table 3). Stocking restrictions have prevented reintroduction of Colorado squaw- fish in the LCRB to date. However, Since the Endangered Species Act was amended by Congress this year to include an "experimental" listing for hatchery-produced endangered fishes, the LCRB states may agree to allow stocking of Colorado squawfish, as they have for the razorback sucker. Hatchery Design and Culture Methods Previous studies and production figu~es provided the information necessary to project the type and size of raceway and/or pond culture facilities needed to produce the 500,000 fingerlings/yr called for in the CPo POND CULTURE: Earthern ponds have been used to rear Colorado River fishes at Hotchkiss NFH, Colorado; Dexter NFH, New Mexico; Page Springs SFH, Arizona and Niland SFH, California. \Jillow Beach NFH used raceways, but reared fish in a lenitic environment using pond culture methods and supplemental feeding with trout feed. In six recirculating S'x 100' raceways, 30,000 to 40,000 fingerlings (2 inches) were produced annually, or roughly 30,000 fingerlings/O.l su~face acres (Hamman 1981a, 1982a, 1982b). Dexter NFH has been able to produce 30,000, 2-4 inch Colorado squawfish per acre. Cannibalism has been a problem at Dexter NFH when producing fish over 2 inches. Hamman (198la) observed cannibalism by 30 mm (1.2 inch) fish in raceways at Hillow Beach NFH but had 80% survival from fry to fingerlings. Vanicek and Kramer (1969) observed that at 50 mm (2 inches) squawfish convert from feeding on plankton to insects. In pond culture, they may convert to eating each other if too many are stocked per pond or natural food becomes scarce. Warm-water hatchery production is dependent on the biological require- ments of the fish, climate, temperature, length of growing season, stocking rates, pond conditions and many other factors. Colorado squawfish fingerlings produced at Dexter NFH in 1982 reached 1.5 to 3.5 inches in one growing season (120 days). In the UCRB under natural conditions, Colorado squawfish normally reach only 2 inches in their first growing season. This is due, in part, to differences in the latitude, elevation and the length of growing season. Humpback and bony tail chub spawn earli~r than Colorado squawfish and grow faster reaching 4 to 5 inches in one growing season (150 days) at Dexter NFH but in the UCRB humpback chub only reach 2-3 inches in the wild. 9