The West Coast region, comprising Washington, Oregon, and California, will be subject to a number of stressors, from increasing temperatures to high levels of ocean acidification and natural climatic variability that can dramatically alter coastal and ocean systems (Feely et al. 2012). Higher ocean temperatures will likely alter the abundance, type, and distribution of some marine species, and increase the risk of harmful algal blooms and diseases such as paralytic shellfish poisoning (Mote et al. 2014). West Coast shellfish fisheries will also be vulnerable to ocean acidification as regional waters are characterized by relatively high CO2 levels (Feely et al. 2012; Walsh et al. 2014).

The marine and coastal ecosystems of the West Coast also experience a large degree of interannual variation due to El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) events, which cause regime shifts between periods of warmer and cooler ocean waters (Brodeur et al. 2008). For example, previous ENSO events in California have caused 2-3°C (3.6-5.4°F) increases in sea surface temperatures and decreases in primary and secondary productivity, limiting prey availability for some fish species (Sydeman and Thompson 2014). The frequency and intensity of ENSO events are expected to increase under changing climatic conditions (Barange and Perry 2009; Yeh et al. 2009). In addition, if coastal habitats such as marshes and tidal flats are unable to migrate inland, rising sea levels could lead to flooding and loss of suitable habitat for spawning and rearing (Glick et al. 2007).

Impacts on Commercial Fisheries

The most important West Coast commercial finfish and shellfish fisheries are vulnerable to increasing temperatures, changes in ocean circulation, and ocean acidification. Many commonly fished species are likely to shift northward and experience declines in production and recruitment in response to warming temperatures (Sydeman and Thompson 2014). Loss of thermally appropriate habitat for pelagic species such as albacore tuna (Thunnus alalunga) and swordfish (Xiphias gladius) may be further compounded by decreasing oxygen levels and a shoaling of the oxygen minimum layer (Sydeman and Thompson 2014). Sardines (Sardinops sagax), however, are likely to respond positively to warmer conditions and experience higher rates of growth and recruitment, leading to a potential expanded California sardine fishery (Sydeman and Thompson 2014).

Salmon populations (Oncorhynchus spp.) will be stressed by both changes in oceanic and freshwater conditions. In California, Chinook (O. tshawytscha) and Coho (O. kisutch) salmon populations are likely to be stressed in marine waters due to changes in ocean circulation (e.g., upwelling timing), which could lead to changes in primary productivity and limited prey availability. Additionally, higher temperatures and altered hydrographic profiles of freshwater streams could result in limited favorable conditions for spawning and rearing, further compounding potential salmon stock declines (Sydeman and Thompson 2014). Greater flooding of freshwater streams could also potentially reduce habitat for salmon feeding, resting, and refuge (CA Fish Passage Forum 2014).

Sablefish (also known as black cod, Anoplopoma fimbria) are among the top ten most economically valuable fisheries in California (Sydeman and Thompson 2014). Sablefish may experience mixed effects from climate change. While warmer temperatures may lead to increased growth for sablefish, these positive effects may be countered by declining abundance of preferred juvenile sablefish prey (i.e. subArctic copepods) due to warming and acidification (Sydeman and Thompson 2014). Rockfish (Sebastes spp.) may experience declines due to loss of their deepwater coral habitat from acidification (WA Blue Ribbon Panel on Ocean Acidification 2012), and mismatches between timing of larvae production and favorable ocean conditions (Sydeman and Thompson 2014). In California, acidification may affect survival and growth of commercially important species such as Dungeness crab (Cancer magister), which have demonstrated decreased juvenile survival in acidic waters in laboratory experiments (Sydeman and Thompson 2014).

Impacts on Recreational Fisheries

Recreational fishing is an important industry throughout the West Coast. In 2011, the industry yielded over $1.6 billion in trips and equipment expenses, $2 billion in sales profits, and supported over 15,000 jobs (NOAA 2014). California is home to over 1.7 million recreational anglers (Schroeder and Love 2002). In Washington and Oregon, a variety of finfish and shellfish species are targeted, such as salmon, rockfish, tuna, halibut, and Dungeness crab. Climate-driven population declines in these targeted species will likely limit recreational opportunities. However, northward shifts of migratory species such as albacore tuna from California (Sydeman and Thompson 2014) could result in increased recreational fishing opportunities in Oregon and Washington.

Impacts on Subsistence & Traditional Fisheries

Subsistence and traditional fisheries will be most affected where many tribal communities are dependent on fish and shellfish for subsistence and cultural purposes (WA Blue Ribbon Panel on Ocean Acidification 2012). Salmon are a traditional food source for Washington tribes, who are co-managers of their coastal fishery resources as delineated in the 1974 Boldt Decision, the result of a 1974 United States vs. Washington court ruling, which reaffirmed the right of Washington tribes to fish in their traditional fishing grounds.

Under the Boldt Decision, federally recognized tribes are recognized co-managers of fishery resources and have access to fifty percent of harvestable salmon (Northwest Indian Fisheries Commission 2014). While tribes are working through associations such as the Northwest Indian Fisheries Commission to adapt to shifts in salmon abundance, they have still observed large declines in the amount of salmon over the past few decades (NAU 2014). These declines have increased tribal dependence on shellfish (e.g., oysters, Crassostrea gigas) for cultural ceremonies and subsistence purposes; as these shellfish populations decline from decreasing pH, tribal communities will experience even more limited access to traditional food sources (WA Blue Ribbon Panel on Ocean Acidification 2012).

Impacts on Aquaculture

Aquaculture is a profitable industry on the West Coast, particularly in the Pacific Northwest. Coastal Washington and Oregon host many shellfish hatcheries and farms, which have experienced higher than historic rates of mortality and lower rates of productivity in the past decade due to the compounding effects of hypoxia and acidification (Barton et al. 2012; Feely et al. 2012; WA State Blue Ribbon Panel on Ocean Acidification 2012). This has led some hatcheries to take adaptive measures, such as monitoring CO2 levels of intake waters and tracking periods of upwelling, so that they can adjust intake levels during periods of unfavorable conditions (Barton et al. 2012). Continued stresses to shellfish aquaculture facilities could negatively impact the economy of the region; some shellfish producers have already moved their larval production facilities to Hawaii to find more favorable conditions for larval growth and survival (Holmyard 2014).