Protecting a displaced species in an altered river: a case study of the endangered Sacramento River winter-run Chinook Salmon

Endangered Sacramento River winter-run Chinook Salmon (Oncorhynchus tshawytscha) exist as a single population that spawns in the Sacramento River downstream of Shasta Dam near Redding, CA. Displaced from their historical habitat after dam construction circa 1940, their survival depends on cold water released from Shasta Reservoir. Managing and recovering the species is further complicated by their anadromous life history, habitat loss and degradation, largescale water supply management, and climate change. The California Department of Fish and Wildlife and other resource agencies coordinate closely to protect the species from extinction, confronting challenges with collaborative restoration and science-driven management. As climate change brings more frequent droughts, warmer weather, and increased variability in precipitation, Sacramento River winter-run Chinook Salmon recovery will require greater collaboration and a shift to more holistic restoration actions that promote and maintain the diversity and resilience of the species and its habitats.

Pacific great blue herons consume thousands of juvenile salmon

An array of predators that consume juvenile salmon (Oncorhynchus spp. Suckley‎, 1861)‎ may account for the poor returns of adult salmon to the Salish Sea. However, the Pacific great blue heron (Ardea herodias fannini Chapman, 1901) is rarely listed among the known salmon predators, despite being regularly seen near salmon streams. Investigating heron predation by scanning nesting sites within 35 km of three British Columbia rivers for fecal remains containing Passive Integrated Transponder (PIT) tags implanted in >100,000 juvenile salmon from 2008-2018 yielded 1,205 tags, representing a minimum annual predation rate of 0.3–1.3% of all juvenile salmon. Most of this predation (99%) was caused by ~420 adult herons from three heronries. Correcting for tags defecated outside of the heronry raised the predation rates to 0.7–3.2%—and was as high as 6% during a year of low river flow. Predation occurs during chick-rearing in late spring, and accounts for 4.1-8.4% of the heron chick diet. Smaller salmon smolts were significantly more susceptible to heron predation than larger conspecifics. The proximity of heronries relative to salmon-bearing rivers is likely a good predictor of heron predation on local salmon runs, and can be monitored to assess coast-wide effects of great blue herons on salmon recovery.

The watershed body: Transgressing frontiers in riverine sciences, planning stochastic multispecies worlds

In conversation with Eva Hayward’s writing on transgender embodiment, this paper explores how beaver modify landscapes differently than human engineers, and how human engineering might be transformed through riverine collaborations with beavers. Considering the body variously as a body of water — a river, which draws together all of the above and underground water in a watershed — as like our own trans bodies, and as a slippery double for the psyche of an Anthropocene engineer, July Cole and I argued that thinking with beaver as stochastic transgressors against Manifest Destiny engineering projects could transfigure engineers approaches to their work and river restoration more broadly. What if, rather than trapping beavers into service as “ecosystem engineers,” we assert that humans should engineer as beavers do, in ways that create porous boundaries between land and water and up- and downstream, by way of stick-and-mud, leaky, temporary dams? Here, I theorize a transfigured watershed body through human-beaver-salmon encounters at three salmon recovery sites in the Pacific west: a Karuk-led project on the Klamath river, agency-led beaver relocation projects in the Methow and Yakima watershed, and a citizen science-agency collaborative project in the beaverless Salmon Creek and Russian River watersheds. All three stories concern river and salmon recovery in the Pacific West, where either humans or beavers have initiated collaborative projects to raise water tables, keep rivers from going dry, and improve salmon habitat. These scientists and local knowledge holders’ encounters with beavers and their ponds thick with salmon are inspiring them to change how they undertake habitat restoration projects and also spurring some to reconsider the proper task of human ecologists and engineers, into a mode inspired by beavers themselves.