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\ Y f • i I Considerations - The potential source(s) of nonnative species that may a potential competitors or predators on the rare Colorado River fish should be identified by reviewing stocking records and assuring that regulations do not allow the legal introduction of new species. Habitats that provide good habitat for potential competitors and predators should be identified and examined for ways to manage such habitats to reduce nonnative species. For example, large impoundment- like backwaters along the Colorado River that are formed by gravel mining could be breached from the river channel, rehabilitated to remove introduced species, and used as "grow-out" ponds for producing larger sizes of the rare species for stocking into the river. o Develop a public awareness program to reduce mortality of rare fish from angling. Rationale - All of the rare Colorado River fish species can be caught by angling. The Colorado squawfish is particularly vulnerable to angling using live bait and lures. The Gila species can be caught rather easily (particularly at certain times of the year such as the summer when they feed on terrestrial insects) using bait. The razorback sucker is not caught easily, but this is probably due to the angling methods and the behavior of the species. The razorback congregates in certain reaches of the river with the ascending hydrograph in the spring for spawning but disperses quickly afterward. Considerations - The angling public are not adequately informed about the endangered or imperiled fish, and have killed the rare fish to eat or by throwing them on the bank since they do not recognize them. Anglers should be informed via regulations and the various information media about the status and the uniqueness of these species. o Identify point sources of toxic contaminants (e.g. leaching from mining activities) and determine solutions for control to improve water quality for the rare fish. Rationale - Mining activities along reaches of the upper basin have adversely affected the species composition and abundance of fish and aquatic invertebrates. For example, almost all animal life was exterminated immediately below a uranium-vanadium mill on the Animas River in Colorado. Although a few tolerant species of invertebrates were found below the mill, only 33% were found 25 miles downstream and the number of species did not fully recover for 35 miles downstream. The abundance of organisms (as the number per square yard) did not recover for 45 miles downstream of the mill. In addition, other point sources of toxic contaminants such as herbicides and pesticides used in agriculture may increase the mortality of rare fish. 16