Chinook response to estuary restoration

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Conceptual Figure Chinook Response.jpg

Estuary restoration has been widely used as a tool to support salmon recovery efforts throughout Puget Sound. While local benefits of estuary restoration have been evaluated extensively, population response to restoration actions has remained elusive. We will evaluate population response to estuary restoration extensively across multiple systems in Puget Sound and intensively within a single data rich system Skagit Delta and document changes in individual condition and smolt to adult return rates as a function of restored estuary habitat. In addition, we will develop an individual-based model for Chinook salmon in the Skagit Delta to infer restoration benefits that are difficult, or impossible, to evaluate with empirical data

Project Objectives

Extensive cross-system analysis

We will integrate several datasets from nine watersheds (Elwha, Dungeness, Skagit, Stillaguamish, Snohomish, Duwamish, Puyallup, Nisqually and Skokomish) to examine the extent to which populations benefit from estuary restoration. A total of 39 capital projects will be assessed for changes in habitat and associated population responses in Chinook salmon. Not all population responses can be evaluated for every restoration project, but each analysis will incorporate data from at least 21 projects. We propose to use an extensive analytical approach, focused on summarizing patterns across systems. Specifically we will:

  • Calculate wetland habitat area before/after restoration action for 9 river deltas in Puget Sound (Table 1)
  • Estimate abundance and size of individuals entering the estuary and nearshore habitat
  • Calculate adult return rates to estimate population productivity before/after restoration

Delta Project Table.jpg

Intensive Skagit Delta analysis

While cross-system comparisons are valuable for assessing benefits of restoration across Puget Sound, they are potentially susceptible to multiple sources of uncertainty and data gaps as outlined above. To complement the broad-scale, cross-system comparison, we will focus on intensively analyzing effects of estuary restoration on Chinook salmon in the Skagit River, which has benefited from intensive watershed monitoring as well as multiple restoration projects established in a BACI analysis framework (Greene et al. 2016). We will produce two specific deliverables as part of this proposal:

  • empirical evaluation of estuary restoration upon cohorts
  • develop an individual-based model for Chinook salmon

Project Leads and Project Partners

Project Information