Coho Life History and Migrations in Tide Gated Lowland Coastal Streams 2020-2022

This Project utilized ODFW Life Cycle Monitoring (LCM) survey and sampling protocols to gather and refine long-term coho salmon monitoring data. This monitoring examines coho abundance, survival, life histories, habitat use and migration in Palouse and Willanch Creek. Transitional tidal habitats have been identified as critical for the resiliency and recovery of Coos River. Current conditions limit connectivity to off-channel winter refuge habitat for multiple cohorts of juvenile salmon. This project informs CoosWA and other management and regulatory agencies of the ecological benefits that tidal restoration provides.

This project proposal leverages a strong foundation of local and regional results that addresses all four primary limiting factors: ‘reduced amount and complexity of habitat; degraded water quality; blocked/impaired fish passage; and uncertainty that there is an adequate combination of voluntary and regulatory mechanisms to ensure success’ (NOAA 2016). Fundamental water quality variables in the Coos Estuary include temperature and salinity. Strong assumptions based on this project previous results (Mackereth 2016) and recent laboratory work (Emerman 2016, Fang 2018) suggests that restoring tidal connectivity for fish passage also improves key water quality attributes such as temperature and salinity gradients (Giannico and Souder 2005, 2018). The tidal zone, including the estuary, may be the last frontier for salmon habitat restoration outside of their ocean range. However, cumulative effects of restoration efforts to date still have not produced detectable signals of population level recovery (Roni et al 2002). In order to more fully release the potential benefits of previous restoration and future efforts, complexity and connectivity have to be mutually addressed and reestablished in ways that interact and magnify habitat and migration advantages (Roni et al 2010). In the tidal zone this translates to restoring a combination of significant abundance and quality of off channel habitat that is accessible in both directions across tidal and seasonal water regimes. Project proposal results will inform expectations and reduce uncertainty of tidal restoration at social, scientific, regulatory and economic levels. Pathways, templates and models for successful lowland tidal restoration will be informed by results of this proposed project. Particularly, spatiotemporal coho migration patterns derived from this project will more accurately inform floodplain channel designs and water management plans so that sufficient exchange across the tidal ecotone is restored. Proposed project results will frame expectations of benefits for ‘working landscapes’ and enlighten transparent application of optimized restoration resources. Successful and sustainable tidal stream restoration will be a shared responsibility between landowners, and multiple federal, state, and local agencies. Only through shared responsibility across tidal zone stakeholders will the support, implementation and success of lowland restoration be realized in a measurable way. This project proposal presents a measurable way to assess restoration effectiveness for salmon. Project products will facilitate design, planning and permitting of future tidal restoration projects that provide significant ecological uplift while sustaining economic productivity. Increased public participation in project development, planning and implementation will be fostered by successful projects that restore working landscapes for all stakeholders.