This is a continuation of a multi-year, multi-institutional study to evaluate the role of changing ocean conditions on growth and survival of juvenile salmon from the Columbia River basin as they enter the Columbia River plume and PNW coastal habitats. Adult returns vary dramatically (over 10 fold) as a result of changing (good or bad) ocean conditions juveniles experience. Evaluating the benefit of restoration efforts in the Columbia River to restore endangered salmon populations needs to consider ocean conditions as a contributing factor to recovery.

OHSU will continue to simulate physical estuarine and plume conditions, and make them available for integration in the cruises and multiple fisheries analyses that require them. This includes both continuing to conduct and analyze underlying circulation simulations (Task 5.1) and filtering the results to derive the estuarine (Task 2.3) and plume metrics (Task 5.3).

Task 2.3. Linking hydrographic conditions with 3-dimensional salmon tracking in the Columbia River estuary

For this task, the NOAA-led team has concurrently measured the 3-dimensional migration pattern of juvenile salmonids relative to the hydrography of the CRE. We hypothesized that the vertical position and location of salmonids is altered when high salinity and low DO are present in the estuary. Specifically, we predict that salmon will hold or move upstream in response to encountering intruding seawater and shoal when encountering low DO. During ebb tides, when water is fresher and normoxic, we expect continued migration and deeper depth distribution.

In FY18, OHSU will contribute to this task through the analysis of the underlying estuarine circulation dynamics, based on existing and on-going circulation simulations. Specifically, OHSU will ensure that metrics characterizing estuarine salinity intrusion and plume characteristics will continue to be computed and are thus available for integration in these analyses as required. OHSU will also begin development of an Individual-based Model (IBM) coupled with the circulation model, to attempt to more closely understand salmon pathways throughout the estuary and early plume.

OHSU will not address DO dynamics unlike originally anticipated.

Task 5.1. Physical Circulation.

The SATURN circulation modeling system, also known as the virtual Columbia River (http://www.stccmop.org/datamart/virtualcolumbiariver), has constituted important infrastructure for the project. Simulations of water levels, salinity, temperature and velocities have supported salmon analyses directly and (as needed) provide underlying flows for use in ecological transport models.

In FY18:
• OHSU will continue to improve the skill of our circulation simulations, and will maintain daily circulation forecasts of circulation to inform NOAA fisheries cruises.
• OHSU will on demand run daily forecasts of turbidity and light attenuation.

Due to the reduced budget levels, OHSU cannot commit to the following originally anticipated tasks:
• Customize daily forecasts of river-to-ocean Columbia River circulation to support salmon release strategies. However, a generic circulation forecast will be maintained, through other funding.
• Analysis of turbidity as an enabler of refugia for salmon predators. However, a sediment transport model has been developed for the estuary and plume, and is being calibrated and validated (all through separate funding).
• Exploration of circulation-based 4D surrogate representations of ecological variables.

Task 5.6. Characterizing Ocean Entry Conditions and their Implications on Adult Returns.

Physical, chemical and biological conditions experienced by salmon at ocean entry play a significant but incompletely understood role in overall survival. To clarify and quantify that role, we have been conducting multiple analyses based on metrics derived from circulation databases. The region associated with “ocean entry” encompasses the coastal jet off the WA coast, the plume (defined by waters of salinity of 28psu or lower) regardless of direction, plume fronts, and the estuary downstream of the salinity intrusion length limit.

In FY18:
• OHSU will concentrate on the update of the time series of plume (volume, area and location) and estuarine (salinity intrusion, salt volume, shallow water habitat) metrics, so that other project participants can conduct analysis based on those metrics.
Due to continued budget reductions:
• OHSU will not at this time pursue the creation of a series of species-specific quantitative correlations between salmon performance and relevant estuarine, plume and climate conditions, with potential to meaningfully encourage, inform, or discourage possible management strategies.

Task 6.2. Engage, advise and inform managers.

This task is critically important as a synthesis of the work conducted to date. While budget reductions do not permit specific commitments, OHSU anticipate continuing—when appropriate—to engage BPA managers to better understand their needs, so that solutions might be explored in eventual future projects. An example of that engagement was the contribution of OHSU, through separate funding, to the U.S. Entity Regional Recommendation for the Future of the Columbia River Treaty after 2024, to the U.S. Department of State.