Northwest Fisheries Science Center (NWFSC) Fish Ecology FE - Migrational Behavior; FE - Watershed


Elwha River dam removal
Elwha River Dam Removal Study
This project focuses on ecosystem response to dam removals on the Elwha River, Washington State. The Elwha Dam removal project is the largest project of its kind in the world and is also the largest restorative action that has taken place in any Western U.S. salmonid Evolutionarily Significant Unit (ESU). We employ a variety of metrics to efficiently monitor ecosystem response over space and time. The project is, in part, based on the development and implementation of the Elwha Monitoring and Adaptive Management Guidelines (EMAM), developed as a collaborative effort between the NWFSC, the Lower Elwha Klallam Tribe (LEKT), and other federal and state partners. This project provides data to assess changes for Endangered Species Act (ESA) listed Elwha River salmonid populations (Chinook salmon (Oncorhynchus tshawytscha), steelhead (O. mykiss), and bull trout (Salvelinus confluentus)), and evaluate the effectiveness of salmon habitat recovery plans and actions. Such analyses are crucial to help inform future large-scale dam removals and other restorative actions for multiple ESUs across the Western U.S. Additionally, this project contributes to future ESA and Essential Fish Habitat (EFH) consultations, the development of Chinook salmon and steelhead capacity models across the Olympic Peninsula, and to understanding salmonid recolonization more generally by incorporating knowledge gained from other dam removal and fish passage projects.

Research Themes

Ecosystem approach to improve management of marine resources
The California Current Large Marine Ecosystem, Puget Sound and the Columbia River Basin are home to a wide range of freshwater and marine resources that provide a wealth of ecosystem goods and services. Ensuring the resiliency and productivity of the California Current and Pacific Northwest ecosystems requires an integrated understanding of their structure, function, and vulnerability to increased human population growth in coastal communities and competing uses of coastal waterways and oceans. The NWFSC‘s approach to understanding these large ecosystems integrates studies across ecosystems (terrestrial, freshwater, and marine) and scientific disciplines to inform resource managers responsible for conserving marine resources.
Habitats to support sustainable fisheries and recovered populations
Healthy oceans, coastal waters, and riverine habitats provide the foundation for aquatic resources used by a diversity of species and society. Protecting marine, estuarine and freshwater ecosystems that support these species relies on science to link habitat condition/processes and the biological effects of restoration actions. The NWFSC provides the habitat science behind many management actions taken by NOAA Fisheries and other natural resource agencies to protect and recover aquatic ecosystems and living marine resources. The NWFSC also maintains a longstanding focus on toxic chemical contaminants, as a foundation for regional and national research on pollution threats to fisheries and protected resources.

Research Foci

Characterize the interaction between marine, freshwater, and terrestrial ecosystem components
Although many species migrate between connected aquatic, marine, estuarine and freshwater environments they are commonly studied and managed as separate ecosystems. Environmental conditions in both marine and freshwater areas are strongly influenced by flows of water, sediment, organic matter and nutrients among ecosystems. Moreover, many threats (e.g., pollution, habitat loss, climate change, etc.) to marine organisms cross land-sea boundaries. Successful management of aquatic systems thus requires an understanding of linkages among ecosystems, including study of how specific habitats (e.g., headwaters, floodplains, submerged aquatic vegetation, nearshore zones, plumes and frontal regions) contribute to the productivity and capacity of ecosystems, and how to prioritize ecosystem protection or restoration within the context of the entire freshwater-estuarinemarine ecosystem.
Characterize the interaction of human use and habitat distribution, quantity and quality
The ability to define the state of an ecosystem requires insight into the natural processes within habitats, and how anthropogenic interactions with these processes can alter ecosystems and marine organisms. A wide diversity of human activities -- land use and water withdrawals, industrialization and dredging, fishing practices and climate change (e.g., ocean acidification) -- directly and indirectly impact critical freshwater, estuarine, and marine habitats. To best manage west coast marine, estuarine and freshwater habitats in a sustainable fashion, it is necessary to map the spatial and temporal footprint of human impacts and review their potential biological impact on each species of interest. Measurement parameters will be developed to determine the full range of human impacts using spatial data and improved habitat classification.
Develop effective and efficient habitat restoration and conservation techniques
Maintaining and re-establishing viability and sustainability of living marine resources requires conservation and rehabilitation or restoration of habitats upon which species depend. Common habitat restoration approaches and tech-niques often presume that habitats are static features of the environment, and that creation of stable habitats is a desirable restoration strategy. However, riverine, nearshore, and marine habitats are created and sustained by dynamic landscape, climatic, and oceanographic processes and biota are adapted to changing habitats that are within the range of natural variability. Hence, current restoration strategies often have limited success, in part because they fail to recognize larger scale processes that drive habitat change, and in part because they fail to recognize intrinsic habitat potential of individual restoration sites. The main goals of this research focus are to: improve understanding of how large-scale processes create diverse and dynamic habitats that support marine and anadromous species, better understand how human activities alter habitat-forming processes and habitats, develop new restoration techniques that are compatible with sustainable habitat-forming processes, and understand the variety of actions needed to adequately conserve intact critical habitats. In addition, NWFSC’s research will improve understanding of how new and existing habitat restoration and protection techniques affect fish and habitat at multiple scales (i.e., reach, watershed, Evolutionarily Significant Unit).
Provide scientific support for the implementation of ecosystem-based management
Fisheries scientists and managers recognize the potential for ecosystem-based management to improve sustain the delivery of ecosystem goods and services, including sustainable fisheries resources. An Integrated Ecosystem Assessment (IEA) is one approach that examines all available information on relevant physical, chemical, ecological and human processes in relation to specified ecosystem management objectives. IEAs provide an efficient, transparent means of summarizing the status of ecosystem components, screening and prioritizing potential risks, and evaluating alternative management strategies against a backdrop of environmental variability. To perform IEAs of major ecosystems will require development of project components, including new and existing data, to develop a suite of indicators that characterize the ecosystem. Careful assessment of ecosystem indicators will provide a powerful means for assessing management efficacy and a basis for adapting and improving management practices. A major focus will be to produce the initial IEA of the California Current LME and then provide annual updates.


adaptive management
Adaptive management of strategies and actions intended to recovery salmon populations
bioenergetics modeling
model of organism's energy budget
dam removal
dam removal
related to removal of dams from rivers
environmental DNA extracted from water samples
effectiveness monitoring
evaluating whether actions had desired effects on physical, chemical, or biological processes
flat depositional feature of a river valley adjoining the channel
food web
complex of interrelated food chains in an ecological community
use of genetic markers to determine differential reproductive success between adults with different life histories
quantifying effects of spawning salmon on resident food web using stable isotopes of C and N
juvenile salmonid
early life stages of salmonids
salmon food webs
recolonization dynamics of salmon following reintroduction
habitat restoration
restoration genetics
genetic analysis to understand success or failure of restoration process
all salmonids
water temperature
temperature of water


Cedar River salmon recolonization
Kiffney, P. M., P. J. Lisi, M. C. Lierrman, J. H. Anderson, S. M. Naman, M. H. Bond, G. R. Pess, M. E. Koehler, E. R. Buhle, T. W. Buehrens, R. S. Klett, J. R. Cram, and T. P. Quinn. In review. Recolonization of a temperate river by anadromous and resident salmonids following restoration of longitudinal connectivity. Ecosphere
Elwha 2021 Chinook salmon escapement
Denton, K., McHenry, M., Moses, R., Ward, E, Stefankiv, O., Urnes, C. Wells, W. and G. Pess. 2022. 2021 Elwha River Chinook Escapement Estimate Based on DIDSON/ARIS Multi-Beam SONAR Data. submitted to Olympic National Park by the Lower Elwha Klallam Tribe in partial fulfillment of action item 1 (adult enumeration) for Elwha monitoring activities
Elwha 2021 Coho salmon escapement
Denton, K., O. Stefankiv, and C.J. Urnes. 2022. Estimating coho salmon escapement and mark rates in the Elwha River in 2021 using multi-beam SONAR technology. This report is provided to Olympic National Park by the Lower Elwha Klallam Tribe as part of the final settlement for Elwha Monitoring
Elwha 2021 smolt enumeration
McHenry, M., Elofson, M., Taylor, M., Liermann, M., Bennett, T., and G. Pess. 2022. 2021 Elwha River Smolt Enumeration Project Report. Submitted to Olympic National Park by the Lower Elwha Klallam Tribe in partial fulfillment of the agreement for performance of monitoring pursuant to the National Park Service’s Chinook and Steelhead Monitoring Plan for the Elwha. This report is provided to Olympic National Park by the Lower Elwha Klallam Tribe as part of the final settlement for Elwha Monitoring
Elwha Dam Removal Citizen Science Handbook
Citizen Science handbook is a work in progress, content for which will continue to be generated and updated by progressive student internships
Elwha Hollings and VCC internships, UW Capstone projects
Ongoing educational opportunities through multiple internship programs
Elwha Sockeye salmon
Quinn, T.P., Pess, G.R., Sutherland, B.J., Brenkman, S.J., Withler, R.E., Flynn, K. and Beacham, T.D., 2021. Resumption of anadromy or straying? Origins of sockeye salmon in the Elwha River. Transactions of the American Fisheries Society, 150(4), pp.452-464.
Elwha Steelhead genetics
Fraik, A.K., McMillan, J.R., Liermann, M., Bennett, T., McHenry, M.L., McKinney, G.J., Wells, A.H., Winans, G., Kelley, J.L., Pess, G.R. and Nichols, K.M., 2021. The impacts of dam construction and removal on the genetics of recovering steelhead (Oncorhynchus mykiss) populations across the Elwha River watershed. Genes, 12(1), p.89.
Elwha chinook salmon spawning distribution
McHenry, M., Pess, G. and J. Anderson, 2022. Spatial distribution of Chinook Salmon (Oncorhynchus tshawytscha) spawning in the Elwha River, Washington State during dam removal and early stages of recolonization (2012-2021). Submitted to Olympic National Park by the Lower Elwha Klallam Tribe in partial fulfillment of the agreement for performance of monitoring pursuant to the National Park Service’s Chinook and Steelhead Monitoring Plan for the Elwha River. This report is provided to Olympic National Park by the Lower Elwha Klallam Tribe as part of the final settlement for Elwha Monitoring
Elwha coho salmon redd enumeration 2011-2021
McHenry, M., J. McMillan, R. Moses, and G. Pess. 2022. Coho salmon relocations and redd surveys in the Elwha River 2011-2021: Summary report. This report is provided to Olympic National Park by the Lower Elwha Klallam Tribe as part of the final settlement for Elwha Monitoring
Elwha foodweb database
Relational database for all Elwha food web related data collected over 2004-2022
Elwha winter steelhead pHOS
Peters, R., Denton, K. and M. Liermann, 2022. Estimating Winter Steelhead pHOS in the Elwha River: 2021. U.S. Fish and Wildlife Service Report. This report is provided to Olympic National Park by the Lower Elwha Klallam Tribe as part of the final settlement for Elwha Monitoring
Molecular ecology collaboration with EFS
Collaboration with EFS scientists (Linda Rhodes) to apply molecular ecology methods to eDNA development
Nearshore Beach Seine Database
2004-2022 database documenting fish abundance/prevalence before/during/after dam removal
Nearshore Forage Fish Publication
Frick, K.E., Kagley, A.N., Fresh, K.L., Samhouri, J.F., Ward, L.S., Stapleton, J.T. and Shelton, A.O., 2022. Spatiotemporal Variation in Distribution, Size, and Relative Abundance within a Salish Sea Nearshore Forage Fish Community. Marine and Coastal Fisheries, 14(2), p.e10202.
Nearshore Herring Genetics Note
Documenting herring population in SJF
Nearshore Salmon Publication
Chinook, Coho, Pink, and Chum abundance/prevalence in SJF
Pacific lamprey recolonization
Hess, J.E., Paradis, R.L., Moser, M.L., Weitkamp, L.A., Delomas, T.A. and Narum, S.R., 2021. Robust recolonization of Pacific lamprey following dam removals. Transactions of the American Fisheries Society, 150(1), pp.56-74.
Spatial patterns of fish response to dam removal
Duda, J. J., C.E. Torgersen, S.J. Brenkman, R.J. Peters, K.T. Sutton, H.A. Connor, P. Kennedy, S.C. Corbett, E.Z. Welty, A. Geffre, J. Geffre, P. Crain, D. Schreffler, J.R. McMillan, M. McHenry, and G.R. Pess. 2021. Reconnecting the Elwha River: Spatial patterns of fish response to dam removal. Frontiers in Ecology and Evolution, 811.


Class Actinopterygii
ray-finned fishes
Class Insecta
Family Salmonidae
Genus Oncorhynchus
Order Salmoniformes
Phylum Chordata
Species Lampetra tridentata
Pacific lamprey
Species Oncorhynchus clarkii
cutthroat trout
Species Oncorhynchus gorbuscha
humpback salmon, pink salmon
Species Oncorhynchus keta
chum salmon, dog salmon, Keta salmon
Species Oncorhynchus kisutch
Coho salmon, silver salmon
Species Oncorhynchus mykiss
rainbow trout, steelhead trout, syeelhead trout
Species Oncorhynchus nerka
kokanee, red salmon, sockeye salmon
Species Oncorhynchus tshawytscha
Chinook salmon, king salmon, spring salmon


Aimee Fullerton
Internal Collaborator
Anna Kagley
George Pess
Principal Investigator
George Pess
Principal Investigator
Karrie Hanson
Kinsey Frick
Krista Nichols
Internal Collaborator
Martin Liermann
Martin Liermann
Peter Kiffney
Internal Collaborator
Sarah Morley
Todd Bennett
Todd Bennett