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10. Plume and nearshore ocean


Monitor ocean conditions and related salmon survival and endorses mitigation and management actions that improve the survival, growth, and viability of Columbia River fish in varying ocean conditions.


The ocean environment, in particular the plume, is treated as an integral component of the Columbia River ecosystem. The survival, growth, and viability of anadromous populations in the Columbia River Basin is affected by physical, biological, and ecological conditions in the ocean. The ocean is not a static environment. As a result of the varying ocean conditions, salmon populations are constantly fluctuating and may pass through cycles of abundance, followed by cycles of scarcity. The storage, release, and impoundment of water changes the pattern of flows and water temperatures downstream from hydroelectric dams and changes the characteristics of the plume.

Understanding the conditions Columbia River anadromous fish face in the ocean will help identify which factors are most critical to survival, growth, and viability and also suggest which mitigation actions will provide the greatest benefit.


  • Identify the effects of ocean conditions and distinguish from other effects: Baseline and real time data is needed to identify and isolate the effects of ocean conditions on the survival, growth, and viability of Columbia River anadromous fish.
  • Manage for variability: Variations in ocean conditions play a large role in the survival of anadromous fish and other species in the Columbia River Basin. The Council supports management actions that help anadromous species accommodate a variety of ocean conditions by providing a wide range of life history strategies.

General measures

  • The Council supports monitoring plume and nearshore ocean conditions and in-river restoration actions to determine those actions of greatest benefit and to separate the effects of ocean-related mortality from that caused in the freshwater part of the life cycle.
  • The federal action agencies shall evaluate the effects of flow regulation on near-shore plume characteristics and salmon and steelhead productivity, abundance, and diversity.
  • The Council supports continued monitoring of the Columbia River plume and ocean conditions, assessment of impacts on salmonid survival, and evaluation of the limits of restoration potential in the basin given variable ocean conditions. Predicting future ocean conditions and anadromous fish returns allows for adjustments to inland actions and may lead to increased survival benefits.
  • The Council supports coordination between ocean scientists and state fish and wildlife agencies and tribes to identify key uncertainties and opportunities to improve inriver management activities based on current ocean conditions.
    • The Council supports efforts by the Ocean and Plume Science and Management Forum and science/policy exchanges to encourage coordination and communication between ocean researchers and fish and wildlife agencies and tribes. The Council will consider recommendations from the forum when making recommendations to Bonneville regarding implementation of this strategy.
    • The Council encourages scientists to develop an annual index of ocean survival from Bonneville Dam back to Bonneville Dam.

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