Overview of Effects of Pacific Coast River Regulation on Salmonids and the Opportunities for Mitigation

Current awareness of the seriousness of losses of salmonid fishes associated with hydroelectric developments and with water abstraction from river systems has stimulated renewed commitments on the part of fishery agencies to mitigation of damage, restoration of degraded habitat, protection and promotion of wild stocks, and increased artificial production of salmonids. To achieve these aims the fish system, the fluvial system, and the system of human values and intentions must be integrated; in addition today\u27s knowledge must be equal to the challenge. Examination of the present status of six aspects of the task shows that (1) facilitation of fish passage at dams is a very high priority but requires greater commitment, (2) hatchery production has generated unreasonable expectations and may be laying the basis for the demise of wild populations, (3) the practice of stocking fry has run ahead of its evaluation, (4) determination of instream flow requirements is bedeviled by spurious quantification, (5) drawdown requirements of impoundments seem incompatible with fishery objectives, and (6) stream habitat improvements give mixed results and may be of restricted application in terms of scale. Yet another limitation of fisheries\u27 aspirations lies in political support. It is concluded that this is a time for stock-taking, improvement of current practices, and assessment of trends