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I I I I I I I I I I I I I I I I I I I BIOLOGICAL OPINION Status of the Species LCR system far exceed the number of native species. Rangewide Present Status The bony tail chub was listed as an endangered species due to massive decline s in or extirpation of all populations throughout the range of the species. The causes of these declines are changes to biological and physical features of the habitat. The effects of these changes have been most noticeable by the almost complete lack of natural recruitment to any population in the historic rang e of the species. Populations are generally small and composed of aging individuals. Recovery efforts under the Recovery Implementation Program in the Upper Basin have begun, but significant recovery results have not been seen for this species. In the Lower Basin, augmentation efforts along the LCR propose to replace the aging populations in Lakes Havasu and Mohave with young fish from protected-rearing site programs. This may prevent the imminent extinction of the species in the wild, but appears less capable of ensuring long term survival or recovery of the bony tail chub. Overall, the status of the bony tail chub in the wild continues to be precarious. A summary discussion on the species' response to the proposed action is provided for the two endangered fish species following the fish critical habitat section. Razorback Sucker Listing History The razorback sucker was first proposed for listing under the ESA on April 24, 1978, as a threatened species. The proposed rule was withdrawn on May 27, 1980, due to changes to the listing process included in the 1978 amendments to the ESA; the amendments required all listings to be completed within two years of publication of the proposed rule and that deadline was not met. The 1978 amendments also required that critical habitat be incl uded in the listing of most species; however, no critical habitat package was developed for the proposed listing of the species. In March, 1989, the Service was petitioned by a consortium of environmental groups to list the razorback sucker as an endangered species. The Service made a positive fmding on the petition in June, 1989, that was published in the Federal Register on August 15, 1989. The finding stated that a status review was in progress and provided for submission of additional information through December 15, 1989. The proposed rule to list the species as endangered was published on May 22, 1990, and the final rule was published on October 23, 1991. The effective date of the rule was November 22, 1991. Critical habitat was designated in 1994 and is discussed elsewhere in this section. Species Description 40