Dam removal has been increasingly proposed as a river restoration technique. In 2011, two large hydroelectric dams will be removed from Washington State's Elwha River. Ten anadromous fish populations are expected to recolonise historical habitats after dam removal. A key to understanding watershed recolonisation is the collection of spatially continuous information on fish and aquatic habitats. A riverscape approach with an emphasis on biological data has rarely been applied in mid-sized, wilderness rivers, particularly in consecutive years prior to dam removal. Concurrent snorkel and habitat surveys were conducted from the headwaters to the mouth (rkm 65-0) of the Elwha River in 2007 and 2008. This riverscape approach characterised the spatial extent, assemblage structure and patterns of relative density of Pacific salmonids. The presence of dams influenced the longitudinal patterns of fish assemblages, and species richness was the highest downstream of the dams, where anadromous salmonids still have access. The percent composition of salmonids was similar in both years for rainbow trout, Oncorhynchus mykiss (Walbaum), coastal cutthroat trout, Oncorhynchus clarkii clarkii (Richardson) (89%; 88%), Chinook salmon, Oncorhynchus tshawytscha (Walbaum) (8%; 9%), and bull trout, Salvelinus confluentus (Suckley) (3% in both years). Spatial patterns of abundance for rainbow and cutthroat trout This article is a U.S. Government work and is in the public domain in the USA. 36 Fisheries Management and EcologyThis article is a U.S. government work, and is not subject to copyright in the United States.(r = 0.76) and bull trout (r = 0.70) were also consistent between years. Multivariate and univariate methods detected differences in habitat structure along the river profile caused by natural and anthropogenic factors. The riverscape view highlighted species-specific biological hotspots and revealed that 60-69% of federally threatened bull trout occurred near or below the dams. Spatially continuous surveys will be vital in evaluating the effectiveness of upcoming dam removal projects at restoring anadromous salmonids.

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Engineered log jams (ELJs) are increasingly being used in large rivers to create fish habitat and as an alternative to riprap for bank stabilization. However, there have been few studies that have systematically examined how juvenile salmonids utilized these structures relative to other available habitat. We examined Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch) and trout (O. mykiss and O. clarki) response to the placement of engineered log jams (ELJs) in the Elwha River, Washington State, USA. We used summer snorkel surveys and a paired control-treatment design to determine how engineered log jams in a large river system affect the density of juvenile salmon. We hypothesized that densities of juvenile salmonids would be greater in habitats with ELJs than in habitats without ELJs in the Elwha River and that this ELJ effect would vary by species and size class. Juvenile salmonid density was higher in ELJ units for all control-treatment pairs except for one pair in 2002 and one pair in 2003. Positive mean differences in juvenile salmon densities between ELJ and non-ELJ units were observed in two of 4 years for all juvenile salmon, trout greater than 100 mm and juvenile Chinook salmon. Positive mean differences occurred in one of 4 years for juvenile coho salmon and trout less than 100 mm. The results suggest that ELJs are potentially useful for restoring juvenile salmon habitat in the Elwha River, Washington State, USA.

Connected river systems confer advantages upon migratory salmonids by facilitating greater life history expression and, ultimately, population persistence. In Washington's Elwha River, two impassable, century‐old hydroelectric dams were removed in the world's largest dam removal project. Dam removal restored access to 130 km of habitat and reconnected headwater, estuarine, and marine areas. We used multi‐year radiotelemetry data to characterize migratory patterns of federally threatened Bull Trout Salvelinus confluentus after dam removal. Bull Trout rapidly responded to barrier removal and were the first among the Pacific salmonids to move into the newly accessible headwaters. Spatial extent and mean distance traveled upriver increased annually, and adults reached the headwaters (64 km) within 3 years of dam removal. Telemetry data revealed that Bull Trout migrated between the river and its estuary (up to 168 km), and spawning migrations occurred in consecutive years. Relocations of Bull Trout in the tidal zone and the presence of bright, silvery colored adults were indicative of marine residence. Length at age of Bull Trout significantly increased after dam removal, and fish captured before and after dam removal were larger at similar ages in comparison with migratory populations throughout their range. We described the diet of Bull Trout captured in the river and estuary after dam removal. Bull Trout primarily consumed Pacific salmonids Oncorhynchus spp., Threespine Sticklebacks Gasterosteus aculeatus, and sculpins Cottus spp., and the prevalence of sculpins in their diet decreased from the estuary to upstream areas. As the length of Bull Trout increased, they progressively consumed larger prey items. In this historic dam removal project, Bull Trout were early and rapid recolonizers and displayed migrations throughout the reconnected river and its estuary. This study is among the first to evaluate Bull Trout responses to dam removal and establishes a baseline to assess future recovery of this threatened species in the Elwha River.

Identifying the source of polychlorinated biphenyls (PCBs) is the first step to eliminating contamination within anadromous salmonids and other aquatic species. We evaluated PCB concentrations in the muscle tissue of 4-year old Puget Sound and coastal hatchery Chinook salmon in an effort to identify potential locations where contamination occurs. Ten muscle samples were taken from each of two Puget Sound hatcheries and two coastal hatcheries in Washington State to determine PCB concentrations. Two technical mixtures of PCBs, Aroclor 1254 and Aroclor 1260, were measured in the tissue samples collected. Aroclor 1254 was detected in all samples, while Aroclor 1260 was detected in 16 of 40 samples. Generalized linear modeling (GLM) was used to evaluate the influence of region (Puget Sound and coast), hatchery, sex, fish length, and percent lipids on PCB concentrations. Twenty different GLMs representing multiple null hypotheses were ranked using Akaike Information Criterion (AIC). Six of the 20 models evaluated had substantial support for being the best model to describe PCB concentrations in Chinook salmon. The six models with substantial support were region and lipids; region; hatchery and lipid; region and sex; region, sex, and lipids; and region and length. Region appears to be the most influential variable explaining the variation in PCB concentrations in Chinook salmon in the Pacific Northwest. PCB concentrations in Chinook salmon muscle tissue from Puget Sound hatcheries were significantly greater (mean 49.26 μg/kg wet weight and standard deviation 40.55 μg/kg) than those from coastal hatcheries (mean 17.41 μg/kg wet weight and standard deviation 6.8 μg/kg). Our results suggest that some contamination likely occurs in the Pacific Ocean. However, a larger source likely exists within Puget Sound or along the migratory route of Puget Sound Chinook salmon. The observation of PCBs in Chinook salmon also has important implications for human health and salmon carcass supplementation.