Willamette River Research Articles

Influence of stream temperature and human disturbance on prespawn mortality of Chinook Salmon in the Willamette River basin

AbstractObjectivePremature mortality of adult female Chinook Salmon Oncorhynchus tshawytscha is a major barrier to population recovery. The Willamette River basin, Oregon, typifies the problems that are faced by fishery managers in the Pacific Northwest (USA). Adult salmon are trapped and transported upstream of dams to access historical spawning grounds, but annual rates of prespawn mortality (PSM) are high (often >40%) and may limit the recovery of natural populations. The purpose of this study was to identify potential factors related to PSM of female Chinook Salmon that are outplanted above dams and incorporate them into a modeling framework to facilitate adaptive management of outplanting operations.MethodsWe evaluated PSM in Fall Creek of the Willamette River basin prior to transport facility improvements in summer and fall of 2010–2017 and postimprovement during 2020–2021. We estimated PSM and conducted exploratory analyses to identify possible nontransport sources of stress that may contribute to the observed high PSM rates. Candidate factors included long‐term elevated temperature exposure, elevated temperature exposure below the trap, total number of outplanted fish, and monthly human disturbance of outplanted fish. We then developed and fit three models, each representing a hypothesis of a factor influencing PSM, incorporated them into a single alternative decision model, and conducted sensitivity analyses.ResultPrespawn mortality averaged 0.66 (ranging from 0.37 to 0.94) over the study period. According to the simulation results, the top two management actions were to exclude human activities—swimming and fishing—from Fall Creek in July and August.ConclusionExpected PSM rates were predicted to be 0.38 when human activity was excluded in July and 0.37 for August. Sensitivity analyses indicated that the most influential decision model component was the choice of the alternative model.

Underwater sound from rotary oscillator and pile driving construction activities - I-205 Bridge over the Willamette River - I-205 Abernethy Bridge, Oregon

The Oregon Department of Transportation (ODOT) is conducting construction work in the Willamette River that involved the installation of piles through the water. There is a potential for impacts to wildlife, primarily fish, due to high noise levels. The project added piers to the existing bridge that consist of 12-foot diameter pile casings and drilled shafts. These casings are installed through rotary-oscillation drilled shafts that extended well below the water. These piles extend 200 feet below the river bottom. A large rotary oscillator was required to install the casings, which was supported on temporary platforms constructed in water. The platforms were supported by hollow 36-inch diameter steel piles. Underwater sounds from rotary oscillators have not been measured extensively in the past. This paper describes the underwater sound levels and characteristics of drilling large diameter casings deep through the substrate using the rotary oscillator. Measurements were also conducted for impact pile driving sounds from installation of the 36-inch diameter piles. The sound measurements evaluated the effectiveness of air bubble curtains meant to reduce sound from impact pile driving and meet permit requirements to minimize exposure of fish to harmful sound levels.

Documenting Historical Anchorworm Parasitism of Introduced Warmwater Fishes in the Willamette River Basin, Oregon

Documenting Historical Anchorworm Parasitism of Introduced Warmwater Fishes in the Willamette River Basin, Oregon

Fish assemblage structure and habitat relationships of a large floodplain river in western North America

AbstractUnderstanding complex river floodplains is critical to conserve species of fish and their ecological functions. In 2011 through 2013, longitudinal gradients in fish assemblage were investigated in the Willamette River in western United States. Of 36,586 individual fish collected, 93% were native and 7% non‐native. The best predictors of fishes collected with a boat electrofisher were percent embeddedness, macrophytes, longitudinal river distance, average depth, and velocity. Habitat type (mainstem or slough) was also a significant predictor. The best predictor of fishes collected in nearshore habitats with a backpack electrofisher were longitudinal river distance, velocity, and percent embeddedness. Fish communities differed significantly between mainstem and slough habitat. Overall, 25 of 40 species had high fidelities to mainstem or slough habitats. Native species showed a high fidelity to both mainstem and slough habitats while non‐native species were significantly related only to slough habitats. Environmental characteristics strongly influenced fish assemblage structure in this large floodplain river. Maintaining and restoring mainstem and off‐channel habitats are critical for maximizing native species resilience in the face of non‐native species encroachment and a changing environment. Restoring the natural flow regime to the degree possible is needed to increase connectivity between the floodplain and mainstem and provide thermal and flood refuges for native fishes. Understanding habitat relationships provides essential context for fish conservation and management by resource agencies and landowners.

Expansion of smallmouth bass distribution and habitat overlap with juvenile Chinook salmon in the Willamette River, Oregon

AbstractSmallmouth bass populations have expanded far beyond their native range and these predatory fish present a pervasive threat to native aquatic species throughout North America. In the western United States, smallmouth bass are now present in river and reservoir habitats where Pacific salmon are found and are considered a potential threat to salmon recovery in many locations. We conducted a study to determine if smallmouth bass are expanding their range in the mainstem Willamette River, Oregon, and developed a model to assess habitat overlap between smallmouth bass and juvenile Chinook salmon. Sampling during 2011–2022 revealed that the distribution of smallmouth bass had expanded throughout that timeframe to encompass the entire mainstem Willamette River, including important rearing habitats for juvenile Chinook salmon. The model predicted that smallmouth bass and juvenile Chinook salmon habitat overlap was substantial, highlighting the need for additional research to evaluate for potential negative impacts to salmon recovery in the basin. The model was also used to evaluate the efficacy of using flow management to reduce interactions between these two species, but the scenarios we examined suggested that this was not a viable option. These results highlight the need for continued research to assess interactions between smallmouth bass and juvenile salmon, and other native species of concern, in the Willamette River Basin. The development of the model is useful for resource managers to understand interactions between these species to prioritize locations for sampling in the future.

The case for basinwide passage and habitat restoration for Pacific Lamprey in the Willamette River basin (Oregon, USA)

AbstractObjectiveThe Pacific Lamprey Entosphenus tridentatus is an anadromous fish that provides many ecosystem services and is important to Native American tribes, which harvest lamprey for cultural uses. The largest harvest of adult Pacific Lamprey in North America occurs at Willamette Falls (WF) in Oregon, USA. Lamprey have experienced conservation problems for decades, and harvest numbers at WF have plummeted approximately 33‐fold from a maximum of over 500,000 during 1946 to an average of about 16,000 per year during 1969–1999. Recent harvest has dropped to less than 6,000 lamprey/year during 2000–2021. However, existing conservation plans do not provide a historical perspective on the lamprey harvest at WF and the cumulative threats in the Willamette River basin that likely caused lamprey harvest reductions. Land development, river impoundment, and water pollution coincided with significant decreases in lamprey harvest at WF. These (and other) threats have resulted in reduced habitat for larval lamprey in the basin and, thus, a reduction in the pheromones they release, which attract adults. Conservation plans do not identify specific, basinwide goals to increase the number of lamprey in general and to provide more lamprey for harvest in particular.MethodsTherefore, in this review paper, we provide a conservation perspective on three topics to increase and monitor lamprey abundance at WF.ResultWe (1) provide an up‐to‐date history of the lamprey harvest and its regulation at WF; (2) recommend addressing the lack of basinwide, lamprey‐specific passage and habitat restoration to improve the quantity and quality of lamprey spawning and rearing habitats; and (3) identify research needs for monitoring the lamprey population(s) at WF.ConclusionWe conclude that lamprey‐specific passage improvements and habitat restoration throughout the Willamette River basin above WF are necessary to bolster abundance.

Intestinal lesions and parasites associated with senescence and prespawn mortality in Chinook Salmon (Oncorhynchus tshawytscha).

Prespawn mortality (PSM) presents a major problem for the recovery of spring Chinook Salmon (Oncorhynchus tshawytscha) populations. In the Willamette River, Oregon, PSM exceeds 90% in some years but factors explaining it are not well understood. We examined intestinal tissue samples using histological slides from over 783 spring Chinook Salmon collected between 2009 and 2021, which included tissues from PSM fish, artificially spawned captive broodstock (BS) and normal river run fish, comprised of trapped (Live) and naturally post-spawned river (RPS) fish collected from the river. We observed degeneration of the intestinal epithelium and loss of villous structure, with concurrent severe enteritis. A natural progression of decline in epithelial integrity (EI) through the summer and fall until spawning and subsequent death was also observed. Live fish exhibited high EI scores (mean = 68%), BS exhibited variable EI scores (35%) and RPS exhibited severe loss of EI (14%). PSM fish exhibited prominent loss of intestinal epithelium with EI scores (13%), very similar to RPS fish, despite having been collected earlier in the year. Hence, we argue that low EI scores are strongly linked with PSM. Ceratonova shasta and Enterocytozoon schreckii were common in all groups, but neither were linked to either PSM or a decline in EI.

Warming of the Willamette River, 1850–present: the effects of climate change and river system alterations

Abstract. Using archival research methods, we recovered and combined data from multiple sources to produce a unique, 140-year record of daily water temperature (Tw) in the lower Willamette River, Oregon (1881–1890, 1941–present). Additional daily weather and river flow records from the 1850s onwards are used to develop and validate a statistical regression model of Tw for 1850–2020. The model simulates the time-lagged response of Tw to air temperature and river flow and is calibrated for three distinct time periods: the late 19th, mid-20th, and early 21st centuries. Results show that Tw has trended upwards at 1.1 ∘C per century since the mid-19th century, with the largest shift in January and February (1.3 ∘C per century) and the smallest in May and June (∼ 0.8 ∘C per century). The duration that the river exceeds the ecologically important threshold of 20 ∘C has increased by about 20 d since the 1800s, to about 60 d yr−1. Moreover, cold-water days below 2 ∘C have virtually disappeared, and the river no longer freezes. Since 1900, changes are primarily correlated with increases in air temperature (Tw increase of 0.81 ± 0.25 ∘C) but also occur due to alterations in the river system such as depth increases from reservoirs (0.34 ± 0.12 ∘C). Managed release of water affects Tw seasonally, with an average reduction of up to 0.56 ∘C estimated for September. River system changes have decreased variability (σ) in daily minimum Tw by 0.44 ∘C, increased thermal memory, reduced interannual variability, and reduced the response to short-term meteorological forcing (e.g., heat waves). These changes fundamentally alter the response of Tw to climate change, posing additional stressors on fauna.

Disturbance and disease: host-parasite interactions in freshwater streams remain stable following wildfire.

Increases in the intensity and frequency of wildfires highlight the need to understand how fire disturbance affects ecological interactions. Though the effects of wildfire on free-living aquatic communities are relatively well-studied, how host-parasite interactions respond to fire disturbance is largely unexplored. Using a Before-After-Control-Impact design, we surveyed 10 stream sites (5 burned and 5 unburned) in the Willamette River Basin, Oregon and quantified snail host infection status and trematode parasite community structure 1year before and two years after historic wildfires. Despite the severity of the wildfires, snail host populations did not show significant shifts in density or size distributions. We detected nine taxa of trematode parasites and overall probability of infection remained consistent over the three-year study period. However, at the taxon-specific level, we found evidence that infection probability by one trematode decreased and another increased after fire. In a larger dataset focusing on the first year after fire (9 burned, 8 unburned sites), we found evidence for subtle differences in trematode community structure, including higher Shannon diversity and evenness at the burned sites. Taken together, host-parasite interactions were remarkably stable for most taxa; for trematodes that did show responses, changes in abundance or behavior of definitive hosts may underlie observed patterns. These results have implications for using parasites as bioindicators of environmental change and suggest that aquatic snail-trematode interactions may be relatively resistant to wildfire disturbance in some ecosystems.

Microbial Degradation of Free and Halogenated Estrogens in River Water-Sediment Microcosms.

Halogenated estrogens are formed during chlorine-based wastewater disinfection and have been detected in wastewater treatment plant effluent; however, very little is known about their susceptibility to biodegradation in natural waters. To better understand the biodegradation of free and halogenated estrogens in a large river under environmentally relevant conditions, we measured estrogen kinetics in aerobic microcosms containing water and sediment from the Willamette River (OR, USA) at two concentrations (50 and 1250 ng L-1). Control microcosms were used to characterize losses due to sorption and other abiotic processes, and microbial dynamics were monitored using 16S rRNA gene sequencing and ATP. We found that estrogen biodegradation occurred on timescales of hours to days and that in river water spiked at 50 ng L-1 half-lives were significantly shorter for 17β-estradiol (t1/2,bio = 42 ± 3 h) compared to its monobromo (t1/2,bio = 49 ± 5 h), dibromo (t1/2,bio = 88 ± 12 h), and dichloro (t1/2,bio = 98 ± 16 h) forms. Biodegradation was also faster in microcosms with high initial estrogen concentrations as well as those containing sediment. Free and halogenated estrone were important transformation products in both abiotic and biotic microcosms. Taken together, our findings suggest that biodegradation is a key process for removing free estrogens from surface waters but likely plays a much smaller role for the more highly photolabile halogenated forms.

Prespawn Mortality of Spring Chinook Salmon in Three Willamette River Populations

AbstractImpassable dams on major tributaries to the Willamette River, Oregon, have restricted access to historical spawning habitat for returning adult Chinook Salmon Oncorhynchus tshawytscha. To restore these populations, some fish are collected and transported in trucks upstream of dams (i.e., adult trap‐and‐haul operations). However, persistently high prespawn mortality (PSM) rates in these programs have hindered conservation efforts. The objective of this study was to evaluate environmental factors and individual fish traits associated with PSM in Chinook Salmon populations that were transported and released upstream of dams in three Willamette River tributaries. Annual PSM of tagged and untagged female salmon ranged from 6% to 88% across 7 years. Mortality was higher in warmer years and in warmer tributaries, consistent with rangewide studies of PSM in Chinook Salmon. Effects of individual traits were mixed across sites: longer salmon and those released relatively early or late in the migrations had higher mortality. We conclude that strategies designed to minimize adult Chinook Salmon exposure to warm water temperatures, as well as additional research into both proximate and ultimate causes of PSM, may lead to better management and conservation outcomes for outplanted populations, including those in Willamette River tributaries.

Impacts of Max-Stable Process Areal Exceedance Calculations to Study Area Sampling Density, Surface Network Precipitation Gage Extent and Density, and Model Fitting Method

Max-stable process (MSP) models can be fit to data collected over a spatial domain to estimate areal-based exceedances while accounting for spatial dependence in extremes. They have theoretical grounding within the framework of extreme value theory (EVT). In this work, we fit MSP models to three-day duration cool season precipitation maxima in the Willamette River Basin (WRB) of Oregon and to 48 h mid-latitude cyclone precipitation annual maxima in the Upper Trinity River Basin (TRB) of Texas. In total, 14 MSP models were fit (seven based on the WRB data and seven based on the TRB data). These MSP model fits were developed and applied to explore how user choices of study area sampling density, gage extent, and model fitting method impact areal precipitation-frequency calculations. The impacts of gage density were also evaluated. The development of each MSP involved the application of a recently introduced trend surface modeling methodology. Significant reductions in computing times were achieved, with little loss in accuracy, applying random sample subsets rather than the entire grid when calculating areal exceedances for the Cougar dam study area in the WRB. Explorations of gage extent revealed poor consistency among the TRB MSPs with modeling the generalized extreme value (GEV) marginal distribution scale parameter. The gauge density study revealed the robustness of the trend surface modeling methodology. Regardless of the fitting method, the final GEV shape parameter estimates for all fourteen MSPs were greater than their prescribed initial values which were obtained from spatial GEV fits that assumed independence among the extremes. When two MSP models only differed by their selected fitting method, notable differences were observed with their dependence and trend surface parameter estimates and resulting areal exceedances calculations.

Seasonal Variations in Triple Oxygen Isotope Ratios of Precipitation in the Western and Central United States.

Triple oxygen isotope ratios offer new opportunities to improve reconstructions of past climate by quantifying evaporation, relative humidity, and diagenesis in geologic archives. However, the utility of in paleoclimate applications is hampered by a limited understanding of how precipitation values vary across time and space. To improve applications of , we present , d-excess, and data from 26 precipitation sites in the western and central United States and three streams from the Willamette River Basin in western Oregon. In this data set, we find that precipitation tracks evaporation but appears insensitive to many controls that govern variation in , including Rayleigh distillation, elevation, latitude, longitude, and local precipitation amount. Seasonality has a large effect on variation in the data set and we observe higher seasonally amount-weighted average precipitation values in the winter (40 ± 15 per meg [± standard deviation]) than in the summer (18 ± 18 per meg). This seasonal precipitation variability likely arises from a combination of sub-cloud evaporation, atmospheric mixing, moisture recycling, sublimation, and/or relative humidity, but the data set is not well suited to quantitatively assess isotopic variability associated with each of these processes. The seasonal pattern, which is absent in d-excess and opposite in sign from , appears in other data sets globally; it showcases the influence of seasonality on values of precipitation and highlights the need for further systematic studies to understand variation in values of precipitation.

A revised taxonomy and estimate of species diversity for western North American Lampetra

Lampreys are an ancient lineage of jawless fish for which the relationships among some lineages are uncertain. We addressed these information gaps for Lampetra species with a focus on western North America. Phylogenetic analysis using all publicly available sequences of two mitochondrial genes—cyt b and COI—supported designation of western North American Lampetra as a distinct genus from Lampetra in Europe, Asia, and eastern North America. Species delimitation analysis of cyt b sequences identified seven species, only three of which are currently recognized. Lampetra ayresii and L. richardsoni, regarded as separate under the “paired species concept,” were not genetically distinct; we recommend synonymizing L. richardsoni with L. ayresii because the latter has precedence, yet continuing to recognize each ecotype using its current common name. Other than the widespread L. ayresii clade, all other species exhibited limited ranges often restricted to one or two locations. Within headwaters of the Willamette River, L. ayresii demonstrated strong genetic structure and lack of gene flow among subbasins, indicating that the subbasin scale may represent an appropriate management unit. However, the appropriate management scale in other areas may differ based on evolutionary histories and gene flow. Subsequent work is needed across western North America to better delineate the ranges of the aforementioned species and to evaluate whether other unrecognized taxa in this lineage may be present.

Caddisfly dives for oviposition: Record-shattering depths and poor life choices in a dammed river system

Oviposition is a critical step in the life cycles of aquatic insects. Adult caddisflies exhibit a variety of oviposition methods. In some species, females enter freshwaters to oviposit on submerged substrates. Here, we compile information on North American caddisflies that are known to dive and swim to oviposit and have sexually dimorphic leg characteristics that may be adaptations for swimming, diving, or both. We also report unexpected underwater captures of adult females of 3 caddisfly species in Willamette Basin reservoirs in Oregon, USA, including the deepest dive depths ever recorded for adult female caddisflies. From these captures, we note sexually dimorphic leg widening in the species Hydropsyche centra Ross, 1938 for the first time, confirm widened mesothoracic leg segments of Hydropsyche occidentalis Banks, 1900 adult females, and note fringes of long hairs on meso- and metathoracic tibiae and basal tarsal segments of Hydroptila argosa Ross, 1938 females. We also note fringes of long hairs on the meso- and metathoracic legs of Hydroptila ajax Ross, 1938 females from the banks of the Willamette River. The presumed oviposition attempts of caddisflies underwater in large, deep reservoirs suggest that these caddisflies may misinterpret oviposition cues in altered habitats and waste reproductive efforts. Greater understanding of caddisfly oviposition methods and abilities may be important for long-term conservation and restoration efforts supporting biodiversity in freshwater habitats.

Using mercury stable isotope fractionation to identify the contribution of historical mercury mining sources present in downstream water, sediment and fish.

Ecosystems downstream of mercury (Hg) contaminated sites can be impacted by both localized releases as well as Hg deposited to the watershed from atmospheric transport. Identifying the source of Hg in water, sediment, and fish downstream of contaminated sites is important for determining the effectiveness of source-control remediation actions. This study uses measurements of Hg stable isotopes in soil, sediment, water, and fish to differentiate between Hg from an abandoned Hg mine from non-mine-related sources. The study site is located within the Willamette River watershed (Oregon, United States), which includes free-flowing river segments and a reservoir downstream of the mine. The concentrations of total-Hg (THg) in the reservoir fish were 4-fold higher than those further downstream (>90 km) from the mine site in free-flowing sections of the river. Mercury stable isotope fractionation analysis showed that the mine tailings (δ202Hg: -0.36‰ ± 0.03‰) had a distinctive isotopic composition compared to background soils (δ202Hg: -2.30‰ ± 0.25‰). Similar differences in isotopic composition were observed between stream water that flowed through the tailings (particulate bound δ202Hg: -0.58‰; dissolved: -0.91‰) versus a background stream (particle-bound δ202Hg: -2.36‰; dissolved: -2.09‰). Within the reservoir sediment, the Hg isotopic composition indicated that the proportion of the Hg related to mine-release increased with THg concentrations. However, in the fish samples the opposite trend was observed-the degree of mine-related Hg was lower in fish with the higher THg concentrations. While sediment concentrations clearly show the influence of the mine, the relationship in fish is more complicated due to differences in methylmercury (MeHg) formation and the foraging behavior of different fish species. The fish tissue δ13C and Δ199Hg values indicate that there is a higher influence of mine-sourced Hg in fish feeding in a more sediment-based food web and less so in planktonic and littoral-based food webs. Identifying the relative proportion of Hg from local contaminated site can help inform remediation decisions, especially when the relationship between total Hg concentrations and sources do not show similar covariation between abiotic and biotic media.

Novel dimensionless index for physically based assessment of thermal refugia characterizes off‐channel habitat on gravel bed river

AbstractIn the Willamette River, OR, main channel temperatures can be too warm for cold water fishes, causing fish to concentrate in secondary channel features that provide thermal refugia. However, temperature regimes vary among and within features. Improved understanding of physical processes controlling thermal regimes is needed. This study developed a dimensionless index for assessment of thermal refugia on the upper Willamette River. The novel hyporheic insolation (HIN) index uses minimal field measurements to predict thermal refugia resulting from buffering. Continuous water temperature measurements at one side channel, eight alcoves, and six beaver ponds provided data to ground truth calculated predictions. Water temperature records were first used to characterize stratification at sites. Calculation of the Richardson number, an index of stability, showed two well‐mixed sites and 13 stratified sites. At stratified sites, calculated values characterized the ratio of cooling flux from hyporheic discharge to heat flux from incoming solar radiation. As increased, measured temperatures at sites decreased. Despite overall scatter, a logarithmic fit to bin‐averaged values showed R2 = 0.91. Calculations suggest that secondary channel features characterized by stratification and cool hyporheic discharge can provide thermal refugia. Accordingly, the HIN index may serve as a practical tool grounded in physical processes governing temperature across a floodplain.

Status of Three Large Populations of Western Pearlshell (Bivalvia: Margaritiferidae: Margaritifera falcata) in the Willamette River Basin, Oregon

Freshwater mussels in the western US are under-studied compared to their eastern cousins, and no western species receive federal protection. Mussel distribution throughout Oregon's rivers and streams is poorly documented, and there are limited historical records to inform assessments of whether, and by how much, current populations may have declined. We launched a long-term project to characterize freshwater mussel populations throughout the Willamette River basin. Surveys were conducted in the mainstem Willamette River and a major tributary, the Middle Fork Willamette, during three years. A two-stage sampling process was used; transects were surveyed qualitatively, and then 0.25 m2 quadrats were placed randomly in transects for quantitative surveys. Mussels visible at the substrate surface were counted using viewing scopes and snorkeling, and scuba diving in deeper water. To facilitate detection of juveniles (≤ 3.50 cm long) and calculation of the burial factor, some quadrats were double sampled; mussels visible at the surface were counted, then the substrate was excavated to a depth of 10 to 20 cm, and all mussels (surface and buried) were counted and their shell length measured. Dense western pearlshell (Margaritifera falcata) populations were found at all locations, but they differed greatly in length class structure, density, and presence of juveniles. Some sites also contained small numbers of floaters (Anodonta spp.), and notably, a single western ridgemussel (Gonidea angulata) was found in a highly urbanized reach. These surveys provide baseline data on the current status of several freshwater mussel populations in the Willamette River basin.

The Undertaking

The Undertaking Ellen Rogers (bio) When J began a side job as an undertaker at a funeral home, our partnership was ending—a death of a different sort. J was mainly a sword swallower. He performed in nouveau cirque shows along the West Coast. Even though he had traveled with tents big enough to hold hundreds of awe-struck showgoers across the country, neither of us ever had much money. He took on extra jobs to fill some of the gaps, most of them a little dangerous; prior to becoming an undertaker he worked as an arborist and an electrician. It was as if he wanted to confront death in all the work he chose. Before I knew him, early on in his career, J was rushed to the emergency room after nicking his epiglottis with his sword during a show—blood on the tip of his blade. He could have died. In the first months we dated, I could barely watch any time he performed. But soon the act felt normal, like breathing. To some, the circus might seem like fun and games, just a distraction from real life. But each act looks life and death right in the face: the drop from an aerial rig, the slice of a sword in the throat. It’s risky business. Performers swallow death, then bow. Fatality is always possible amidst impossible feats. Each show shows us all that death will cull and how it could. Then the glorious circus ends, and the train leaves town. [End Page 57] I was awed by these lessons even as I struggled with them. Since J and I broke up, my struggles with these lessons have not gone away. Though I don’t long to resurrect our relationship, this part of my life, even years later, haunts me—the daring I felt I never quite picked up, the wildness I later ceded to comfort, the sense of misdirection in my own life that didn’t end when we did. ________ I first met J at a music festival, not far from the Nooksack River’s teal waters, at the height of blackberry season when the Pacific Northwest teems with sunlight and no one wants to be inside. Even the way he walked was playful. His allure was his rare freedom. We got together and stayed partners for years. J made a point of meeting everyone. He shook any stranger’s hand, then spun his signature black felt bowler hat upside down on his finger and tossed it via triple-flip back onto his head—a little magic for the shuffling grocery store line or someone’s morning commute. For a person who risked his life with each performance, he was jovial and warm, nothing grim about him. I will always admire this, though sometimes I felt drab in comparison back then, forgettable except for the fact that I stood next to him. At my worst, I used to wonder if our partnership was to blame, as if his personality overshadowed mine. Our circus friends were brave and playful and crafty. I admired them too, even though I often felt awkward around them, not cut out for the bold life they led. People use the phrase “when pigs fly” to mean something will never happen. But when a friend wore a pig suit for a comedy burlesque act set to “Harlem Nocturne,” J and the crew figured out how to hoist her through dancing clouds on stage. Every day, what I didn’t think could happen happened. Whatever they dreamed, they did. Rose-petal confetti. A swordfish sword to swallow, a bouquet to swallow, a glowing neon sword to swallow that lit J from within. A tour down the Willamette River on a homemade boat that doubled as a floating stage. Impossibility flew above our heads, then stuck its landing. [End Page 58] The weekend before I broke up with J, we decorated his small circus tent as if for a funeral, his chosen theme for that night’s show. He borrowed a casket from work. We made bouquets of dead branches and dried flowers. We strung fraying fabric strips into white webs overhead and hauled...

Move, migrate, or tolerate: Quantifying three tactics for cold‐water fish coping with warm summers in a large river

AbstractMainstem rivers are important for provisioning cold‐water fisheries and often support fluvial life histories that grow much larger than resident counterparts in tributaries. However, mainstem rivers are also warmer than tributaries during summer and more tightly coupled to regional climate. A key challenge is to understand how fluvial life histories cope with summer temperatures in mainstem rivers, both now and in a warmer future. Here, we outline three options: tolerance, exploitation of cool microhabitats, or migration to cooler tributaries. We quantified the relative prevalence of these responses in the wild using a Lagrangian approach. Specifically, we used temperature transmitting radio‐tags to track coastal cutthroat trout (Oncorhynchus clarkii clarkii) habitat use across 100 km of the Willamette River, which exhibited a maximum temperature of 22°C. We found that 89.8% of fish stayed in the mainstem and tolerated high temperatures; 6.5% of the population exploited cool floodplain alcoves; and 3.7% moved into a cool tributary, the McKenzie River. We also found that on average, larger fish opted to use cold‐water refuge habitats rather than tolerate mainstem river temperatures. The expression of all three coping tactics suggests this population has adaptive capacity to respond to future warming. More work is needed to understand how the relative expression of these tactics change depending on the severity of heat stress or nontemperature attributes of mainstem, floodplain, and tributary habitat.