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. DRAFT APPENDIX E . OBSERVATIOOS OF. RADIarAGGED NJRTHERN PIKE INTROIXJCTIOO . This appendix represents the results of a winter habitat study of northern pike (ESox lucius) conducted concurrently with the winter habitat study described in the Final Report. The work for this report was conducted during the winter of 1987-88 at the request of the Bureau of Reclamation as a supplement to Contract No. 6-CS-40-04490, entitled "Winter Habitat study of Endangered Fish - Green River". The seven progress reports submitted during the course of the 1987-88 winter investigations which are mentioned in the Introduction of the Final Report, include information on northern pike. . Objectives The objectives of this investigation were to: 1. Determine possible interactions between northern pike and the endangered fish, particularly Colorado squawfish, in the Green River using radiotelemetry. . 2. Assess winter habi tat use by northern pike in the Green River using radiotelemetry and IFIM. . 3. Contingent on follow up effort, determine spawning areas for northern pike during the early spring in the Green River using radiotelemetry. Background . This investigation was conducted in association with BOR's ongoing program on endangered fishes of the upper Colorado River Basin. That program is part of the responsibility of federal agencies as prescribed by the Endangered Species Act of 1973, as amended in 1978, to protect and, where possible to promote the recovery of these fishes. . Biological information collected on these endangered species suggest that competition or predation by exotic fishes may be a factor to their demise. . Northern pike have become increasingly abundant in the Green River during the past decade. pike were probably introduced into the Green River Sub-Basin via stocking in Elk Head Reservoir in the upper Yampa River. Although they have expanded their range downstream into Lake Powell, they are most abundant in the Green River above Desolation Canyon and in the Yampa River. . Northern pike are large pi sci vorous predators simi lar to Colorado squawfish. Interest in the interactions between pike and the native fishes of the Colorado River Basin has increased during the last three years as pike have become more abundant. 47 .