Salmonid distribution and abundance in the context of Elwha River dam removals

Removal of two dams on the Elwha River, Washington from 2011 to 2014 has begun to restore natural sediment processes to the coastal environment near the river mouth. Since 2006, we have been collecting data on shallow subtidal (nearshore) fish communities near the Elwha River and at reference sites in the Strait of Juan de Fuca to assess fish response to sediment changes resulting from dam removal. Juvenile salmon (Chinook, coho, pink and chum salmon) migrate through this region, which also supports ecologically important forage fish and endemic benthic fauna. Beach seine samples collected annually from April through September from over 20 sites span pre-removal, high impact (during dam removal), and post-removal years. Annual catches included 23,093 to 92,677 individuals from 45-55 species. Trends in species richness and abundance were variable over this time period. Forage fish dominated our catches followed by salmonids. In this analysis we explored patterns of juvenile salmonid abundance in relation to dam removal, environmental variables, site characteristics (including community composition), and year/season using a Bayesian hierarchical modeling framework and multivariate analyses. Chinook salmon show a tenfold variation in abundance over the years examined. Catches of Chinook and coho salmon were dominated by locally released hatchery fish with high variability between sampling sites. Throughout this region we have seen a marked decrease in coho salmon catches in recent years. Understanding what biotic and abiotic factors contribute most to this variability in salmon abundance and distribution may help tailor future dam removal processes or reframe management decisions

Movement of transplanted adult salmonids in previously inaccessible habitat in the Elwha River

The removal of the Elwha and Glines Canyon Dams on the Elwha River will renew access for anadromous salmonids to 70 miles of high quality habitat located primarily within Olympic National Park. Concurrent dam removals began in 2011, with complete fish passage projected in 2014. While the long-term benefits to anadromous populations are undisputed, release of stored sediment behind the dams is temporarily elevating suspended solids and degrading existing spawning habitat downstream of the Elwha dam. To minimize deleterious effects in the lower river, give populations an early opportunity to spawn and imprint on upstream habitats, and examine the response of anadromous fish to the newly available areas, Chinook and coho salmon and steelhead were moved upstream of Elwha and Glines Canyon dams in 2011 and 2012. We radiotagged and tracked 20 adult Chinook salmon, 47 adult coho salmon, and 37 steelhead to determine spatial and temporal movements and spawning in tributaries and the main stem river. An additional 10 coho and 1 chum salmon were tagged in the lower river and released to continue their migration. Fish movements were monitored using fixed sites and mobile tracking. We also observed substantial volitional fallback and subsequent spawning or migrational movement in the lower river by all both Chinook and coho salmon. Kelting behavior was common in tagged steelhead. We observed coho salmon and steelhead redds in Little River, Indian Creek, the mainstem Elwha River, and side channels of the river. Two Chinook redds were seen in the area upstream of Glines Canyon Dam. Tributaries seeded with adults retained spawers while mainstem releases provided for more exploratory migrational movements. The offspring from these relocated adults will have direct outmigration access to the ocean and the river will be open for upstream migration when they return as adults. Transplanting adult salmonids is labor intensive and requires source populations from downstream for seeding, but can result in spawning activity in new areas and can be managed to include hatchery and wild fish to supplement naturally occurring colonizations

Spatio-temporal variation in the nearshore forage fish community in the Strait of Juan de Fuca

Nearshore marine habitats in the Salish Sea support populations of many fish species including migrating juvenile salmon, benthic sculpins, and rearing and spawning forage fish. The Strait of Juan de Fuca (SJF) is critical as a corridor between the Pacific Ocean and inland water bodies. Though known to utilize this area, the population dynamics of ecologically important forage fish are poorly understood. Over 9 years of monthly beach seine sampling (April – September) at 24 sites along 70 km of coastline in the SJF, we have observed high variability in fish catch across years, sites, and seasons. Annual catches ranged from 23,093 to 92,677 individual fish divided among 45 to 55 species. Forage fish were represented by 9 species and were numerically the dominant group, accounting for 87.8% of the catch from all sampling areas combined. Three forage fish species dominated, thus warranting in-depth investigation: Pacific Herring (Clupea pallasii), Pacific Sand Lance (Ammodytes hexapterus), and Surf Smelt (Hypomesus pretiosus). Influence of individual species varied, yet drove the fish assemblage structure. We explored effects of temporal and spatial variability on forage fish occurrence, abundance, and community composition using descriptive statistics and a Bayesian hierarchical modeling framework. Additionally, the removal of two large dams on the adjacent Elwha River, which released stored sediment into our sampling area, provided us an opportunity to examine forage fish response to a localized habitat perturbation. Spatially, individual species may avoid regions of high perturbation but dramatic variations in distribution and abundance of the greater forage fish community are temporally driven by larger scale changes. Management plans directed at forage fish should take into consideration how variation in abundance at regional scales and consistent population responses to large-scale environmental fluctuations may drive forage fish populations over time

Response in Nematocyst Uptake by the Nudibranch Flabellina verrucosa to the Presence of Various Predators in the Southern Gulf of Maine

Volume: 205Start Page: 367End Page: 37

Concurrent Sessions B: Integrating Fish Physiology or Behavior with Passage - Small Dams, Big Impacts; Adult Salmonid Migrations in the Umatilla River Basin

Like large hydropower counterparts in the Columbia River, low-elevation dams and irrigation diversions may impede adult salmonid migrations as fish approach spawning areas in smaller tributaries. The Umatilla River has seven low elevation dams that may obstruct Chinook salmon and steelhead access to historic spawning areas. We used radio telemetry to examine fallback rates, passage routes, rates, and delays, holding and spawning locations, and maximum upstream distribution of Chinook salmon and steelhead in the Umatilla River basin (Oregon). Analyses focused on the effects of project modifications on salmonid passage and overall system use by fish. Detections at fixed receivers and mobile tracking of 476 tagged steelhead, 130 spring Chinook salmon, and 206 fall Chinook salmon from 2009-2012 provided data for these analyses. Recent project modifications at individual diversion structures have resulted in marked improvements in fish passages times. Species show preference for different aspects of the modifications; for example, jump pools are used by spring Chinook more than steelhead. System passage times have also been markedly reduced. Locating key holding and spawning areas will provide information for additional habitat and restoration needs. The determination of upstream distribution and spawning of hatchery fish will allow managers to better assess the use of hatchery releases to supplement historical spawning areas

Movements of sub-adult Chinook salmon (Oncorhynchus tshawytscha) in Puget Sound, Washington, as indicated by hydroacoustic tracking

Alternative forms of migratory behavior can have substantial consequences for the growth, survival, and fitness of the individuals involved. Salmonids vary in the tendency of individuals to migrate to marine waters (anadromy) or remain in freshwater habitats. In addition, substantial variation in migratory patterns can exist among anadromous and resident species. This talk summarizes our use of hydroacoustic telemetry to investigate the movement patterns of anadromous Chinook salmon Oncorhynchus tshawytscha remaining in the marine waters of Puget Sound after ocean entry rather than continuing out to the coastal waters of the North Pacific Ocean, as is typical of the species. We then compared the movement patterns of Chinook salmon with those of a closely related species, coho salmon O. kisutch. Most (37 of 53 = 70%) Chinook salmon remained in Puget Sound (“residents”) and few of those left the region within Puget Sound where they were first captured, despite ready access to suitable habitat elsewhere. However, 30% of the individuals, termed transients, subsequently left Puget Sound and moved to the coastal Pacific Ocean. Residents and transients did not differ in initial body size, date or place of tagging, or rearing history (hatchery or wild). Combined with other sources of information, these data support the conclusion that Chinook and coho salmon display alternative forms of migratory behavior (resident and transient) that are best described as modes along a continuum rather than discrete categories. However, in both species the residents showed very limited movement within Puget Sound; this behavior affects their exposure to agents of natural mortality, fisheries, and other physiological processes such as the uptake of chemical contaminants

Nearshore Forage Fish Populations in the Context of Elwha River Dam Removals

Removal of two dams on the Elwha River, Washington, is expected to help restore natural sediment processes to the coastal environment near the river mouth. Since 2006 we have been collecting data on shallow subtidal (nearshore) fish communities near the Elwha River and at reference sites in the Strait of Juan de Fuca to assess fish response to sediment changes resulting from dam removal. Ecologically important forage fish spawn and rear, and juvenile salmon migrate through these areas. Beach seine samples to date include 5 years pre-removal, 2 high impact years, and one year post-removal. Trends in species richness and abundance were consistent throughout, with reference areas possessing more species and overall abundance of fish than sites near the river mouth. Given the important role of forage fish in the ecosystem, both as plankton predators and as prey for marine fish including listed salmonids, we focused this analysis on population patterns within the forage fish community. Forage fish dominate our samples across years, but the influence of individual species varies, and can drive fish assemblage structure between sampling regions. We explored patterns of abundance in relation to dam removal, environmental variables, site characteristics, and season using a Bayesian hierarchical modeling framework and multivariate analyses. Forage fish abundance has increased at sampling sites since dam removal; Pacific Herring (Clupea pallasii), Night Smelt (Spirinchus starksi), and Pacific Sand Lance (Ammodytes hexapterus) have shown the greatest increases over all areas. Though variable, overall abundance of forage fish increased more following dam removal within the impacted region than within the reference regions. We will continue to monitor nearshore fish populations in this region, including use of genetics and stable isotopes to explore forage fish population structure, as the system evolves towards a more natural sediment regime and material distributes from the Elwha River watershed

Passage behavior and survival of radio-tagged yearling Chinook salmon and steelhead at Ice Harbor Dam, 2007

Report of the National Marine Fisheries Service to the U.S. Army Corps of Engineers, Walla Walla, Washington</p