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W f J . San Juan-Colorado: Investigations in Cataract Canyon in 1985 (Valdez et al. 1985) also failed to yield any razorback sucker, but four were captured in 1980-81 by USFWS (Valdez et al. 1982) Razor- back are incidental species in Lake Powell, and a few are reported annually from various locations, including the upper riverine portion of the mouth of the Colorado and Dirty Devil Rivers. Remarks: The razorback is so rare that basic information is difficult to acquire. The razorback population extant appears to be senescent and declining. The fish should be classified endangered and protected by Federal Statute. DISCUSSION The status of the four endangered Colorado River fishes has not measurably improved since 1981, and in the continuing absence of sub- stantive and effective management practices can be expected to further decline. As determined by the Colorado River Fishes Recovery Team (USFWS. 1984), fUrther fragmentati on of the range of the Colorado squaw- fish may r~lt in our inability to ever fully recover this species. The lack of reproduction of the razorback sucker emphasizes an urgent need for basic life history requirements of this species. Finally, the disturbing increase of "intergrades" in the Gila compl"x, indi- cates that these three former '~good species" may now be exposed to environmental factors favoring genetic introgression. Our conclu- sions regarding Gila, based on the field observations and pictures of hundreds of specimens, is that the Gila complex is a highly vari- able polymorphic group that is perhaps-a-continuum of ecotypes. Rather than ignore this taxonomic dilemma, we find this proposition not inconsistent with provisions of the Endangered Species Act: the genetic diversity of this polymorphic complex must be protected without delay. Again, an acceleration of applied research into specific life history requirements and genetic characteristics of all upper basin Colorado River Gila species should commence ~ithout further delaj. . ... The concept of protecting known areas of "abundance" (concentra- tion areas), based on catch-effort using various collecting gear and techniques has recently surfacp.d as a protective strategy for the en- dangered fishes. A white paper, entitled "Rare and Endangered Colo- rado River Fishes Sensitive Areas," has been generated by combined effort of USFWS and the Biology Subcommittee of the Upper Colorado Rlver Basin Coordinating Comlldttee. That document identifies speci- fic river sections for consideration in the manipulation of flows and provisions of non-flow alternatives. We consider the formulation of this document an important first step toward the development of basin- wide management strategies, with agreement by bielogists and developers alike. We emphasize, however, that the continuing decline of these -27- r f I I ~ fi " ~. , , ~ ~ I