Beamer, E., Greiner, C.M., Barber, J.S., Ruff, C.P. and Wolf, K., 2020. Climate vulnerability assessment for habitat and associated fisheries in the inland waters of northern Washington State. Skagit River System Cooperative, La Conner, WA. pp. 105.

For the marine inland waters of northern Washington, the spatial extent of habitats of fish and shellfish has been reduced extensively over the last century by human land use actions such as shoreline armoring, pollution, agricultural practices, and urbanization. In addition to human impacts, ongoing and long-term climate change is thought to influence the suitability of marine habitats to support productive populations of fish and shellfish species. To better understand future habitat availability within the study area, we developed a framework to evaluate the vulnerability of certain fish and shellfish species and their associated habitats to future environmental change. Species included in the framework were selected for their cultural and commercial importance to the Swinomish Indian Tribal Community and other residents of the greater Puget Sound area. This framework paired spatially explicit measurements of landscape features (e.g., shore type) with environmental response metrics including erosion and sea surface temperature (SST). These landscape and environmental data were then combined with known physiological thresholds of the target fish and shellfish species to estimate environmental conditions experienced by individual species during specific life stages.
Specifically, we developed a qualitative tool for assessing habitat risk to wave energy and sea level rise (the “wave and sea level rise resilience” model). We then created predictive models for SST using landscape features and 6,672 in situ observations collected within the study area and applied these models to predict current SST (the “water temperature model”) conditions throughout the study area. Landscape-scale model predictions of SST under current conditions were compared with literature-based estimates of thermal tolerance for juvenile Chinook salmon (Oncorhynchus tshawytscha), cockle clam larvae (Clinocardium nuttallii), and postlarval and juvenile Dungeness crab (Metacarcinus magister) to estimate the percentage of habitat providing favorable metabolic conditions for each species under those current conditions. Finally, we assessed how habitat availability for the three species may change under future climate change by applying a 2.2°C increase in SST across the study area based on projections generated at the scale of the North Pacific Ocean.
The study area for this project encompasses inland waters throughout northern Washington including the majority of Whidbey Basin and Admiralty Inlet, the northern inland waters of Bellingham and Samish Bay, the eastern section of the Strait of Juan de Fuca, the southern section of the Strait of Georgia, and the San Juan Islands. We used the regionally accepted Puget Sound Nearshore Ecosystem Restoration Project Shoreline Process Units as the basic spatial unit for analysis. We associated shore type and landscape characteristics to each of the 1,742 spatial units within the study area. Shore types included barrier beaches, estuaries (large river estuaries and pocket estuaries), human-modified beaches, pocket beaches, rocky beaches, and sediment source beaches. Landscape characteristics were fetch, depth of adjacent marine water, distance from the nearest large river, and distance from entrance of the Strait of Juan de Fuca.
Wave and sea level rise resilience (WSLRR) model: We estimated considerable differences in resilience to wave energy and sea level rise across each shore type. These results were likely driven by spatial variability in fetch, geomorphic, and existing shoreline armored scores. In general, we found that large river estuaries and human-modified shore types were projected to be the least resilient to wave energy and sea level rise while barrier beaches, sediment source beaches, and rocky beaches were projected to be the most resilient.