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LOWER BASIN PROGRAMS Lower Basin Management Prospectus After decades of extensive research and stocking of the listed fishes in the Lower Basin, Region 2 of the FWS initiated a management plan, now incorporated in a document called the "prospectus" for the listed, big river fishes in that subbasin, which was circulated for review in February 1995. The prospectus cites the need to institutionalize funding for research and recovery efforts in the Lower Basin and focuses primarily on the circumvention of recruitment failure by managing wild and hatchery fishes in semi-natural and newly built habitats. The prospectus explains: "this rationale differs considerably from those offered in existing recovery plans" and in the "documents developed to guide the management of these fishes in the upper Colorado River basin". While its goal was stated as the "stabilization and maintenance self- perpetuating populations of all four big river fishes in the Lower Colorado River basin", the prospectus concentrates on the hatchery propagation of the Lake Mohave stocks of razorbacks and bonytail, and the recruitment and maintenance of these stocks in controlled Lower Basin habitats from which predators can be excluded. This emphasis for the Lower Basin is substantiated by years of study on Lake Mohave stocks by Dr. W.L. Minckley and others which indicated that predation by the non-native fishes was the single most likely factor precluding recruitment of razorbacks in the Lower Basin's developed habitats. The more recent of these studies show that razorback larvae harvested from natural reproduction in Lake Mohave and held in protected, predator free backwater habitats, where they are grown to about 300 mm in length, can be tagged and returned to the reservoir and are large enough to avoid most predators. A number of these grown out and tagged razorbacks have been recaptured along with the older razorbacks. Razorbacks are also being similarly reared in hatcheries and stocked in Lake Havasu and downstream backwaters, and there is some evidence that they are also surviving. The approach taken by the prospectus differs from that taken by the Upper Basin and San Juan Programs under which the restoration and protection of instream flows and connected floodplain habitat is proceeding concurrently and adaptively with genetic banking, hatchery propagation, grow out, and the control of non-native fishes. The prospectus does not put a priority on project re-operation and the protection of instream flows as essential for recovery, because the Lower Basin is largely developed and has little remaining natural flow regimes. It instead is immediately concerned with preventing the extinction of the razorback and bonytail and emphasizes identifying, enhancing, and managing habitats in the Lower Basin where recruitment and grow out of these fishes can occur. Indeed, the prospectus suggests that the habitat needed for recovery should be defined, at least in the Lower Basin, in terms of the removal or exclusion of non-native predators and of refugias and isolated habitats for species survival, recruitment and maintenance. This approach assumes long-term intervention to perpetuate these stocks, and it is not clear whether these stocks might eventually be able to sustain themselves without the managed exclusion of non-native fishes. Project re-operation or other types of habitat restoration are not ruled out, but the document also does not specify what, where, or how other recovery strategies should be pursued in the Lower Basin. While it does not address the artificial propagation and grow out of squawfish in the Lower Basin, the prospectus does recommend that the status of the re-introduced squawfish populations in the Salt and Verde Rivers be changed to "experimental, essential" which would then invoke most of the regulatory protections of the ESA and allow designation of critical habitat for such re- introduced populations. It.is not clear if this is a recommendation to amend 18