Steelhead vulnerability to climate change in the Pacific Northwest

Abstract

Summary1. Steelhead (Oncorhynchus mykiss) and other Pacific salmon are threatened by unsustainable levels of harvest, genetic introgression from hatchery stocks and degradation or loss of freshwater habitat. Projected climate change is expected to further stress salmon through increases in stream temperatures and altered stream flows. 2. We demonstrate a spatially explicit method for assessing salmon vulnerability to projected climatic changes (scenario for the years 2030-2059), applied here to steelhead salmon across the entire Pacific Northwest (PNW). We considered steelhead exposure to increased temperatures and more extreme high and low flows during four of their primary freshwater life stages: adult migration, spawning, incubation and rearing. Steelhead sensitivity to climate change was estimated on the basis of their regulatory status and the condition of their habitat. We assessed combinations of exposure and sensitivity to suggest actions that may be most effective for reducing steelhead vulnerability to climate change. 3. Our relative ranking of locations suggested that steelhead exposure to increases in temperature will be most widespread in the southern Pacific Northwest, whereas exposure to substantial flow changes will be most widespread in the interior and northern Pacific Northwest. There were few locations where we projected that steelhead had both relatively low exposure and sensitivity to climate change. 4. Synthesis and applications. There are few areas where habitat protection alone is likely to be sufficient to conserve steelhead under the scenario of climate change considered here. Instead, our results suggest the need for coordinated, landscape-scale actions that both increase salmon resilience and ameliorate climate change impacts, such as restoring connectivity of floodplains and high-elevation habitats.

Coastal livelihood vulnerability to marine resource degradation: A review of the Indonesian national coastal and marine policy framework

“…[7,47]), together with measures that improve management effectiveness, or strengthen or restore ecosystem health (e.g. [48][49][50]). Interventions that reduce livelihood sensitivity include provisions for alternative livelihoods (although these can have counterproductive outcomes if inadequately planned and implemented [11,51]), subsidies, assistance in fishing diversification and intensification, improved market access (all of which can both decrease and increase sensitivity, depending on which species are targeted and how measures are distributed within a community [11,33]), and investment in improved health and nutrition [47].…”

Assessing freshwater life-stage vulnerability of an endangered Chinook salmon population to climate change influences on stream habitat

“…Taking into account the influence of a changing climate on habitat will improve the likelihood that restoration actions will succeed in recovering at-risk species (Waples et al 2009, Beechie et al 2013. Our modeling found that the restoration actions that most addressed the impacts of increasing water temperature were restoring forests, both riparian and upland, toward estimated historical conditions and reducing anthropogenic impervious area.…”

“…For steelhead Oncorhynchus mykiss, some evidence suggests that decreasing summer discharge may be the most limiting factor in the Wenatchee River and elsewhere in the Upper Columbia River Basin (Wade et al 2013). In contrast, in colder regions where cool water temperatures may be further below the high temperature tolerance threshold, warming may have the opposite effect and in some locations may lead to an increase in fish survival and production (Leppi et al 2014).…”

“…Future increases in air temperature and changes in mountain snowpack are projected to exacerbate high water temperatures and low flows during the summer (Mote & Salathé 2010) as well as increase the frequency of high discharge events in other seasons (Warner et al 2014), putting additional environmental stresses on fishes (Mantua et al 2010). An understanding of these effects can ensure that habitat restoration efforts are targeted to ameliorate the anticipated negative impacts (Beechie et al 2013. However, only a few population studies have analyzed life-stage-specific responses to climate change in a life-cycle context (e.g.…”

Review of Tools for Identifying, Planning, and Implementing Habitat Restoration for Pacific Salmon and Steelhead

“…) or vulnerability of species to climate change (Wade et al. ). This information can help identify and prioritize basins and stream reaches that need restoration and protection or reaches that under various climate change predictions may become unsuitable for salmon and other fish species.…”