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  • Trophic impacts of bald eagles in the Puget Sound food web


Northwest Fisheries Science Center (NWFSC) Conservation Biology CB - Ecosystem Science


Food web role of bald eagles
Trophic impacts of bald eagles in the Puget Sound food web
This project is developing models to examine the ecological roles of bald eagles in the Puget Sound region. It is primarily being done by NMFS FTEs, in collaboration with scientists from the State of Washington and University of Washington. Trophic ecology of bald eagles will be described using ecosystem-scale food web models and bioenergetics models. Working models and scientific manuscripts will be the main products. The target audience is the Puget Sound Partnership, resource management agencies, and stakeholders in the Puget Sound area. This is an on-going, stand-alone project without a firm deadline.

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.
Recovery and rebuilding of marine and coastal species
The Pacific Northwest is home to several iconic endangered species, including Pacific salmon and killer whales, and several rockfish species. Mandates such as the Endangered Species Act, MagnusonStevens Act, and the Marine Mammal Protection Act, grant NOAA Fisheries the authority to manage the recovery of depleted species and stocks. The NWFSC contributes to species recovery through research, monitoring and analysis, providing NOAA managers and regional stakeholders the tools and information they need to craft effective regulations and develop sustainable plans for recovery.

Research Foci

Characterize ecological interactions (e.g. predation, competition, parasitism, disease, etc.) within and among species
Predator-prey interactions, inter- and intra-specific competition, and parasites and pathogens influence the survival, growth, and reproductive success of anadromous and marine fishes, marine mammals and other marine organisms. Moreover, anthropogenic stressors, such as pollution and fishing, can influence these interactions. Because of the complex nature of these interactions, addressing questions about ecological interactions will require novel field and laboratory studies and analyses. This includes ecosystem models, use of innovative technologies (e.g., otolith microchemistry and stable isotopes), integration of sample collection efforts with those of the Ocean Observing System entities on the west coast, and quantifying interactions among environmental stressors, species behavior and ecosystem processes.
Characterize the population biology of species, and develop and improve methods for predicting the status of populations
To evaluate species status and recovery, it is necessary to understand key aspects of the population biology of the species in question. This includes basic information on abundance, age structure, recruitment, spatial distribution, life history and how the species interacts with its ecosystem. For some recovering species, including most overfished groundfish stocks, many ESA-listed Pacific salmon stocks, and high profile species such as Southern Resident killer whales, this basic information is often reasonably well understood. For other recovering species, such as Pacific eulachon and some ESA-listed rockfish species, even basic information (e.g. stock abundance) is unknown. Even for well-studied species, key information on survival rates for critical life stages and how the environment affects these vital rates is lacking. Without basic information on species dynamics, achieving other goals such as quantifying relationships between human activities and species recovery or even knowing if species recovery goals are being met will not be successful. The NWFSC, in partnership with regional stakeholders, including states, tribes and industry, is conducting research to collect and monitor critical demographic information for recovering species.
Understand how climate influences ecosystem variability
Effective ecosystem management will require an understanding of how climate variability and climate change will alter riverine, estuarine, and marine habitats and consequently how this will affect ecosystem status, function and recovery. Key research elements include better understanding of historical ecological variability through traditional (i.e., indigenous) sources, exploring the vulnerability of key species and biotic communities to expected habitat changes, including decreasing stream flow, increased flood frequency, increasing stream temperature, sea level rise, ocean acidification, shifts in ocean currents, and changed frequency and extent of deoxygenated zones. A secondary goal is to improve understanding of how ecosystems respond to year-to-year and decadal climate variability. Achieving these research goals will provide NOAA and state and local governments with the knowledge and tools needed to incorporate climate change and variability into management of living marine resources.


bald eagle
bald eagle (Haliaeetus leucocephalus)
bioenergetics modeling
model of organism's energy budget
climate change
changes in climate
ecosystem modeling
end-to-end models
food web
complex of interrelated food chains in an ecological community


Modeling climate change impacts on overwintering bald eagles
Harvey et al., 2012, Ecology and Evolution 2:501-514


Species Haliaeetus leucocephalus
bald eagle
Species Oncorhynchus keta
chum salmon, dog salmon, Keta salmon


Chris Harvey
Principal Investigator
Thomas Good
Internal Collaborator