Middle Fork Willamette River Research Articles

Damming salmon fry: evidence for predation by non‐native warmwater fishes in reservoirs

AbstractComplex predator–prey interactions over time have the potential to limit survival of threatened native species. Reservoirs created by large dams in temperate ecosystems are sites where both coldwater and warmwater fish species overlap in distributions, forming assemblages that would not occur under natural settings. For example, in many western North American reservoirs, juvenile native salmonids now overlap with native and non‐native predators such as Northern Pikeminnow Ptychocheilus oregonensis and bass Micropterus spp. Currently, native Northern Pikeminnow are considered by many to be the most formidable predator of salmon smolts in freshwater systems of the Pacific Northwest. However, their consumption of salmon fry and the role of non‐native warmwater predators remain unclear. Predation on fry has proved more difficult to identify than on smolts, due to smaller sizes and high digestibility, but is important for prioritizing management strategies. Here, we use multiple lines of evidence, including large datasets of stable isotopes and fish stomach contents, to identify which fish consume Chinook Salmon Oncorhynchus tshawytscha fry (<55 mm) as they enter reservoirs below their spawning grounds in the Middle Fork Willamette River, Oregon. Unexpectedly, we found that non‐native warmwater game fishes, including bass and crappie Pomoxis spp., preyed more heavily on Chinook Salmon fry in the spring than native fish predators including Northern Pikeminnow. Of the native species, only Rainbow Trout Oncorhynchus mykiss showed evidence for significant predation on Chinook Salmon fry. Fish management in reservoirs that attempts to promote both warmwater and coldwater recreational fisheries simultaneously may thus be in conflict, necessitating future prioritization of species composition in individual reservoirs. This prioritization is especially important as these species include popular game fishes as well as salmonids threatened under the U.S. Endangered Species Act. Understanding predation pressure by popular invasive game fishes on sensitive life stages will allow managers and policymakers to evaluate trade‐offs in the management of these novel assemblages.

Landlocked Pacific Lamprey Entosphenus tridentatus in the Middle Fork Willamette River, Oregon

Pacific Lamprey Entosphenus tridentatus is an anadromous fish native to the west coast of North America and the Pacific coast of Asia. In the 1950s, construction of dams on the Middle Fork Willamette River blocked upstream migration of adult Pacific Lamprey which resulted in their extirpation from otherwise suitable habitats. We report evidence of landlocked Pacific Lamprey surviving for >40 years after the construction of two high-head flood control dams (Dexter and Lookout Point) in the Middle Fork Willamette River 355.0 and 360.3 km upstream of the Pacific Ocean, respectively. In 2001, six putative Pacific Lamprey (two juveniles and four larvae) were captured using an electro shocker during a stream survey, 21.7 km upstream of Lookout Point Dam (the uppermost of these dams) and were entered into the Smithsonian National Museum of Natural History’s Division of Fishes collection. We re-examined these specimens, and their morphometric measurements and dentition are consistent with Pacific Lamprey. Additional evidence supports the existence of a landlocked population of Pacific Lamprey that resided upstream of these two impassable dams for approximately five generations. To our knowledge, this is the first report of Pacific Lamprey surviving for multiple generations upstream of impassable impoundments. However, no Pacific Lamprey have been detected in recent targeted surveys, indicating that this population has since been extirpated or exists in very low numbers.

Using otolith chemical and structural analysis to investigate reservoir habitat use by juvenile Chinook salmon Oncorhynchus tshawytscha.

Isotopic composition of (87) Sr:(86) Sr and natural elemental tracers (Sr, Ba, Mg, Mn and Ca) were quantified from otoliths in juvenile and adult Chinook salmon Oncorhynchus tshawytscha to assess the ability of otolith microchemistry and microstructure to reconstruct juvenile O. tshawytscha rearing habitat and growth. Daily increments were measured to assess relative growth between natal rearing habitats. Otolith microchemistry was able to resolve juvenile habitat use between reservoir and natal tributary rearing habitats (within headwater basins), but not among catchments. Results suggest that 90% (n = 18) of sampled non-hatchery adults returning to the Middle Fork Willamette River were reared in a reservoir and 10% (n = 2) in natal tributary habitat upstream from the reservoir. Juveniles collected in reservoirs had higher growth rates than juveniles reared in natal streams. The results demonstrate the utility of otolith microchemistry and microstructure to distinguish among rearing habitats, including habitats in highly altered systems.

Analyses of Genetic Variation in Populations of Oregon Chub, a Threatened Floodplain Minnow in a Highly Altered Environment

AbstractThe Oregon chub Oregonichthys crameri is a small floodplain minnow endemic to the Willamette River basin of western Oregon. Historically the species was widely abundant and probably relied on periodic floods for dispersal and genetic exchange among populations. The species has declined substantially in the past 100 years due to habitat alterations and the introduction of nonnative species and is currently listed as threatened under the U.S. Endangered Species Act. Information on the level of genetic variation within and among populations did not exist when the species was listed or when a recovery plan was being developed. In this study, we used a suite of nine microsatellite loci to characterize genetic variation within and among 16 sampling locations and provide information to help guide future recovery efforts. Even though many locations are presently isolated from one another, we observed relatively high levels of genetic variation within collections. Temporal samples revealed that the levels of genetic variation were stable over time despite fluctuations in abundance. Estimates of effective population size (Ne) for three sampling locations ranged from approximately 120 to 220 and suggest that there is no immediate threat from inbreeding or genetic drift. We observed a significant level of genetic variation among sampling locations (global FST = 0.078) and significant differences in allele frequencies among all sampling locations. Our results suggest that the different locations represent distinct populations of Oregon chub and that greater levels of gene flow occur among populations within the Santiam and Middle Fork Willamette River subbasins. The information presented in this study will help guide Oregon chub recovery efforts, including the refinement of recovery areas and future population introduction efforts, and will help address the challenge of managing populations largely in isolation from one another in order to minimize threats from nonnative species.

Reservoir entrapment and dam passage mortality of juvenile Chinook salmon in the Middle Fork Willamette River

Abstract – High‐head dams in Oregon’s Willamette River basin inhibit seaward migration and present significant mortality risks to ESA‐listed juvenile Chinook salmon (Oncorhynchus tshawytscha). Over 7 years, we passively collected 13,365 downstream‐migrating juvenile salmon in rivers above and below Willamette dams. Most salmon emigrated from upstream sites in February–June, but passed dams in November–February when reservoirs were drawn down near annual lows, and access to deep‐water passage routes improved. Samples collected above reservoirs were dominated by subyearlings, whereas below‐dam samples were a phenotypically diverse mix of subyearling, yearling and older salmon. The life history data indicated that Willamette reservoirs seasonally entrap many salmon and some sea‐ready smolts probably residualise. Annual dam‐passage mortality estimates were 8–59% (mean = 26%). Individual salmon mortality risk increased significantly with body length and varied with reservoir elevation and discharge. Operational changes that allow timely volitional emigration and development of less hazardous passage routes would benefit this threatened population.

Assessing Mercury Exposure and Effects to American Dippers in Headwater Streams near Mining Sites

To evaluate mercury (Hg) exposure and possible adverse effects of Hg on American dipper (Cinclus mexicanus) reproduction, we collected eggs and nestling feathers and the larval/nymph form of three Orders of aquatic macroinvertebrates (Ephemeroptera, Plecoptera and Trichoptera = EPT) important in their diet from three major headwater tributaries of the upper Willamette River, Oregon in 2002. The Coast Fork Willamette River is contaminated with Hg due to historical cinnabar (HgS) mining at the Black Butte Mine; the Row River is affected by past gold-mining operations located within the Bohemia Mining District, where Hg was used in the amalgamation process to recover gold; and the Middle Fork Willamette River is the reference area with no known mining. Methyl mercury (MeHg) concentrations (geometric mean) in composite EPT larvae (111.9 ng/g dry weight [dw] or 19.8 ng/g wet weight [ww]), dipper eggs (38.5 ng/g ww) and nestling feathers (1158 ng/g ww) collected from the Coast Fork Willamette were significantly higher than MeHg concentrations in EPT and dipper samples from other streams. Total mercury (THg) concentrations in surface sediments along the same Hg-impacted streams were investigated by others in 1999 (Row River tributaries) and 2002 (Coast Fork). The reported sediment THg concentrations paralleled our biological findings. Dipper breeding territories at higher elevations had fewer second clutches; however, dipper reproductive success along all streams (including the lower elevation and most Hg-contaminated Coast Fork), was judged excellent compared to other studies reviewed. Furthermore, MeHg concentrations in EPT samples from this study were well below dietary concentrations in other aquatic bird species, such as loons and ducks, reported to cause Hg-related reproductive problems. Our data suggest that either dipper feathers or EPT composites used to project MeHg concentrations in dipper feathers (with biomagnification factor of 10-20x) may be used, but with caution, to screen headwater streams for potential Hg-related effects on dippers. When actual feather concentrations or projected feather concentrations are equal to or lower than concentrations reported for the Coast Fork, dippers are expected to reproduce well (assuming adequate prey and suitable nest sites). When Hg concentrations are substantially higher, more detailed investigations may be required. Birds feeding almost exclusively on fish (e.g., osprey [Pandion haliaetus]) and usually found further downstream from the headwaters would not be adequately represented by dippers given the higher MeHg concentrations in fish resulting from biomagnification, compared to lower trophic level invertebrates.

Comments on “Alteration of Streamflow Characteristics Following Road Construction in North Central Idaho” by John G. King and Larry C. Tennyson

Water Resources ResearchVolume 22, Issue 5 p. 829-830 CommentariesFree Access Comments on “Alteration of Streamflow Characteristics Following Road Construction in North Central Idaho” by John G. King and Larry C. Tennyson Patrick Teti, Patrick TetiSearch for more papers by this authorSteven Northway, Steven NorthwaySearch for more papers by this author Patrick Teti, Patrick TetiSearch for more papers by this authorSteven Northway, Steven NorthwaySearch for more papers by this author First published: May 1986 https://doi.org/10.1029/WR022i005p00829Citations: 1AboutReferencesRelatedInformationPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessClose modalShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. References Bosch, J. M., J. D. Hewlett, A review of catchment experiments to determine the effects of vegetation changes on water yield and evapotranspiration, J. Hydrol. Amsterdam, 55, 3– 23, 1982. Dixon, W. J., M. B. Brown, L. Engelman, J. W. Frame, M. A. Hill, R. I. Jennrich, J. D. Toporek, BMDP Statistical Software, 725, University of California Press, Berkeley, 1981. Harr, R. D., W. C. Harper, J. T. Krygier, Changes in storm hydrographs after road building and clear-cutting in the Oregon Coast Range, Water Resour. Res., 113, 436– 444, 1975. King, J. G., L. C. Tennyson, Alteration of streamflow characteristics following road construction in north central Idaho, Water Resour. Res., 208, 1159– 1163, 1984. Lyons, J. K., R. L. Beschta, Land use, floods, and channel changes: Upper Middle Fork Willamette River, Oregon (1936–1980), Water Resour. Res., 19, 463– 471, 1983. Milhous, R. T., Effects of sediment transport and flow regulation on the ecology of gravel-bed rivers, Gravel-Bed Rivers R. D. Hey, J. C. Bathurst, C. R. Thorne, 819– 842, John Wiley, New York, 1982. Ostle, B., R. W. Mensing, Statistics in Research 3, 596, Iowa State University Press, Ames, 1975. Steel, R. G. D., J. H. Torrie, Principles and Procedures in Statistics, 481, McGraw-Hill, New York, 1960. Citing Literature Volume22, Issue5May 1986Pages 829-830 ReferencesRelatedInformation RecommendedReply [to “Comments on ‘Alteration of Streamflow Characteristics Following Road Construction in North Central Idaho’ by John G. King and Larry C. Tennyson”]John G. King, Water Resources ResearchThe Influence of Urban Development Patterns on Streamflow Characteristics in the Charlanta MegaregionNeil Debbage, J. M. Shepherd, Water Resources ResearchStreamflow characteristics of physiographic units in the northeastWilliam E. Sopper, Howard W. Lull, Water Resources ResearchAnalysis of subsurface storage and streamflow generation in urban watershedsAditi S. Bhaskar, Claire Welty, Water Resources ResearchA monthly streamflow modelOmid Mohseni, Heinz G. Stefan, Water Resources Research

Land use, floods, and channel changes: Upper Middle Fork Willamette River, Oregon (1936–1980)

Flow trends and channel characteristics from 1936 to 1980 were evaluated for the Middle Fork Willamette River, which drains a 668‐km2 forested watershed in the Cascade Mountains of western Oregon. An inventory of aerial photographs from 1959 to 1972 shows that landslides associated with roads and in clearcuts were 27 and 23 times more frequent, respectively, than in forested areas. Numerous landslides unloaded sediments directly into the drainage system; most landslides appear to have been initiated during a large flood (return period greater than or equal to 100 years) of December 22, 1964. Analysis of precipitation and peak flows (greater than 100m3 s−1) from 1958 to 1980 by means of power function models suggests a trend of increasing flows as timber harvesting and road building expanded in the basin. Changes in channel pattern, documented from aerial photographs, show major increases in channel width from 1959 to 1967 and a trend of decreasing width from 1967 to 1980. During summer low flows in 1979 and 1980, 65 cross sections of the channel were surveyed to provide detailed measurements of existing channel conditions. Channel widths of 62% of the aggraded reaches were significantly greater (α=0.05) than those for nonaggraded reaches.