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INTROIXJCTIOO The purpose of this Special Supplemental Report is to provide investigators working with the Gila complex with photographs and meristics of fish with bony tail characteristics recently captured in the Colorado River within Cataract Canyon. Also provided in this report are photographs of Gila elegans from the Dexter National Fish Hatchery for comparison. There is no particular comment solicited from this report. It is intended as an informational document to distribute current information to investigators working with endangered species of the Colorado River Basin. In light of the apparent current low numbers of wild ~. elegans and the interest to procure wild fish for hatchery stocks (Protocol For The Handling And Transport Of wild Bonytail In The Upper Colorado River Basin, USFWS 1988), this possible occurrence of the species in the upper basin could constitute a significant find of genetic stocks. Certainly specimens from the Cataract Canyon area need to be closely examined to ascertain their position in the Gila complex. Investigations sponsored by the Bureau of Reclamation in Cataract Canyon since June of 1985 have yielded a total of 13 probable adult and juvenile bonytail (Gila elegans). Nine of these fish were captured on our third trip through the canyon for 1988 (July 12-18). Capture information, meristics, and photographs associated with some of these fish are included in this report. These fish continue to add evidence to the existence of a possible enclave of Gila elegans in Cataract Canyon. Jlun'HOuS All fish documented in this special report were captured with either experimental gill nets, trammel nets, or electrofishing. The experimental gill nets consist of 4 panels, each 25 feet long and 6 feet deep, with square mesh of 0.5, 1.0, 1.5, and 2.0 inches. The trammel nets are 75 feet long and 6 feet deep with outer mesh ,of 10 inches and inner mesh of 2 inches. The nets are made of multifilament to reduce stress and abrasion to the fish, and they are set for only 2 hours at a time. The electrofishing unit is a Coffelt VVP-15 under normal operating levels of 100-200 volts and 5-10 amps. Further details on the methodology used in this investigation are presented in Final Summary Reports of 1985, 1986, and 1987. All fish were photographed on a grid board divided into 1-em units. The following measurements were taken for each fish: TL = total length, FL ... forked length, SL ... standard length, WI' ... weight. Also, the following meristics were measured with calipers: p1-p2 ... distance between insertion of pectoral and pelvic fins, HUMP ... nuchal depth, CP D MAX ... caudal peduncle maximum depth, CP D MIN ... caudal peduncle minimum depth, CPL ... caudal peduncle length, ~... head length, DFBL ... dorsal fin base length, AFBL ... anal fin base length, DR ... dorsal rays, AR ... anal rays. The following ratios were also recorded since they are part of the Bonytail Protocol: CPL/HL - caudal peduncle length divided by head length, <1.0 in G. elegans, HL/CP-P MIN ... head length divided by caudal peduncle miniumum depth, <5.0 in G. elegans.