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


Calawah River Riverscape
Calawah River Riverscape Study
The objective of this study was to identify the patterns of juvenile salmonid distribution and relative abundance in relation to habitat correlates. It is the first dataset of its kind because the entire river was snorkeled by one person in multiple years.

During two consecutive summers, we completed a census of juvenile salmonids and stream habitat across a stream network. We used the data to test the ability of habitat models to explain the distribution of juvenile coho salmon (Oncorhynchus kisutch), young-of-the-year (age 0) steelhead (Oncorhynchus mykiss), and steelhead parr (= age 1) for a network consisting of several different sized streams. Our network-scale models, which included five stream habitat variables, explained 27%, 11%, and 19% of the variation in the density of juvenile coho salmon, age 0 steelhead, and steelhead parr, respectively.

We found weak to strong levels of spatial auto-correlation in the model residuals (Moran's I values ranging from 0.25 - 0.71). Explanatory power of base habitat models increased substantially and the level of spatial auto-correlation decreased with sequential inclusion of variables accounting for stream size, year, stream, and reach location. The models for specific streams underscored the variability that was implied in the network-scale models. Associations between juvenile salmonids and individual habitat variables were rarely linear and ranged from negative to positive, and the variable accounting for location of the habitat within a stream was often more important than any individual habitat variable. The limited success in predicting the summer distribution and density of juvenile coho salmon and steelhead with our network-scale models was apparently related to variation in the strength and shape of fish-habitat associations across and within streams and years.

Research Themes

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

Develop methods to use physiological, biological and behavioral information to predict population-level processes
Understanding the biological processes occurring within organisms is a powerful way of understanding how environmental changes affect those organisms. Genetics, developmental, physiological and behavioral studies all provide important information for effective species recovery and rebuilding. Integrating this information into models is vital to predict how populations will respond to natural or human perturbations, and to assess the constraints to stock rebuilding efforts. For example, data on thermal tolerance and physiological responses to temperature can be used to explore changes caused by shifts in climate on reproductive behavior and productivity, viability, movement, habitat selection, and population dynamics. Similarly, data on contaminants that impact physiological processes (immune system, growth, development, reproduction, and general health) are critical in determining how these compounds affect population dynamics. Data on biological responses of organisms to ocean acidification are useful for understanding how acidification may affect individual development and survival. The NWFSC collects such information for several species that are of concern, targets of fisheries or otherwise important for overall ecosystem function. NWFSC scientists will continue to expand current efforts and develop methods to incorporate physiological, biological and behavioral data into population models in order to predict population-level processes from these individual level data.


the quantity or amount of something
the way in which something is shared among a group or spread over an area
related to fish habitat (terrestrial or marine)
juvenile salmonid
early life stages of salmonids


None associated


Class Actinopterygii
ray-finned fishes
Family Salmonidae
Genus Oncorhynchus
Kingdom Animalia
Order Salmoniformes
Phylum Chordata
Species Oncorhynchus kisutch
Coho salmon, silver salmon
Species Oncorhynchus mykiss
rainbow trout, steelhead trout, syeelhead trout


George Pess
Martin Liermann
Principal Investigator