Assessment of the Fishery Improvement Opportunities on the Pend Oreille River: Recommendations for Fisheries Enhancement: Final Report.

摘要

This report recommends resident fish substitution projects to partially replace anadromous fish losses caused by construction of Grand Coulee and Chief Joseph Dams. These recommendations involve enhancing the resident fishery in the Pend Oreille River as a substitute for anadromous fish losses. In developing these recommendations we have intentionally attempted to minimize the impact upon the hydroelectric system and anadromous fish recovery plans. In this report we are recommending that the Northwest Power Planning Council direct Bonneville Power Administration to fund the proposed enhancement measures as resident fish substitution projects under the NPPC's Columbia Basin Fish and Wildlife Program. The Pend Oreille River, located in northeast Washington, was historically a free flowing river which supported anadromous steelhead trout and chinook salmon, and large resident cutthroat trout and bull trout. In 1939, Grand Coulee Dam eliminated the anadromous species from the river. In 1955, Box Canyon Dam was constructed, inundating resident trout habitat in the river and creating many back water and slough areas. By the late 1950's the fishery in the reservoir had changed from a quality trout fishery to a warm water fishery, supporting largemouth bass, yellow perch and rough fish (tenth, suckers, squawfish). The object of this study was to examine the existing fishery, identify fishery improvement opportunities and recommend fishery enhancement projects. Three years of baseline data were collected from the Box Canyon portion of the Pend Oreille River to assess population dynamics, growth rates, feeding habits, behavior patterns and factors limiting the fishery. Fishery improvement opportunities were identified based on the results of these data. Relative abundance surveys in the reservoir resulted in the capture of 47,415 fish during the study. The most abundant species in the reservoir were yellow perch, composing 44% of the fish captured. The perch population in the river is stunted and therefore not popular with anglers. Pumpkinseed composed 16% of the total catch, followed by tenth (9%), largemouth bass (8%), mountain whitefish (6%), largescale sucker (5%), northern squawfish (4%) and longnose sucker (3%).