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RZ14: Salt River from the US 60/SR 77 bridge to Roosevelt Lake. Razorback suckers were extirpated from the Salt River by the 1960s. A cooperative effort was started in 1981 to reintroduce the species, apparently with little success. Hydrologic conditions, water quality, and physical habitat have remained similar to the historic, natural conditions of this reach. However, as in other areas, the threats to recovery are mainly the many introduced fishes (including the highly predaceous flathead and channel catfishes).. RZ15: Verde River from Prescott National Forest Boundary to Horseshoe Lake. Wild razorback suckers have not been reported from the Verde River since 1954. Hatchery-raised individuals have been stocked since 1981, but the reintroduction apparently was not successful until recently, when larger individuals were stocked (K. Young, personal communication, Arizona Game and Fish Department). Flows within this reach have been altered by several diversion projects, but water levels remain adequ-ate. Water quality parameters such as salinity, nutrients, and temperature have been changed, but remain within tolerance of aquatic species. The presence of nonnative fishes and heavy infestation of parasitic copepods have hampered reintroductions of razorback suckers in the Verde River (Creef and Clarkson 1993, Clarkson et al. 1993). Critical habitat areas RZ1, RZ2, RZ3, and RZ9 overlap with critical habitat designated for the other big river Colorado River endangered fishes. RZ4, RZ6, RZ7, and RZ8 overlap with designated Colorado pike minnow area. RZ10 and RZ11 overlap with humpback chub and the bonytail chub areas respectively. Critical habitat designations RZ14 and RZ15 are areas where experimental, non- essential populations for the Colorado pike minnow have been authorized. RZ15 also overlaps with proposed critical habitat for the threatened spikedace, Meda fulgida. Target Population Numbers Recovery plans strive to present recovery objectives in quantified terms. However, it is difficult to determine needed population sizes of an endangered species because the species is almost always a rare one, which makes data difficult to obtain. Thus, the means for determining what population sizes are needed to facilitate down listing or delisting are often lacking. The development of quantitative recovery goals will require determining population sizes of the fish in various locations that can be expected to persist over time, i.e., wild populations that would be "viable" in nature. In order for down listing or delisting to occur, a species would have to maintain populations for some time period, during which it would be expected to survive natural and anthropogenic threats. Although minimum 33