Research
Habitat Selection Experiments for Juvenile Chinook Salmon in Lakes
Collaborators: C Sergeant (graduate student), N Overman, S Damm, J Mattila (staff)
Support: Seattle Public Utilities
The purpose of this study is to use controlled experiments to examine selectivity of juvenile Chinook salmon for different littoral habitats available in Lake Washington. Little is known about habitat use by juvenile chinook salmon in lakes, yet this is the predominant rearing habitat and migratory corridor for stocks in the Lake Washington–Lake Sammamish drainage. Previous studies by USFWS (Tabor et al. 2002) and WDFW (Fresh) indicate that juvenile Chinook mainly utilize the littoral zone during lake residence. Lake Washington’s complex shoreline is highly urbanized and dominated by docks and bulkheads, but it is still poorly understood how juvenile Chinook relate to these shoreline characteristics in Lake Washington. We will examine selectivity for specific bottom substrates, slope, shoreline type, and levels of habitat complexity. These experiments will be repeated for different size classes of chinook salmon during daylight, twilight, and night conditions, and in the presence or absence of key predators.
These results should help identify critical habitat needs for early life stages of Chinook salmon that rear and migrate through Lake Washington. This information will help guide future conservation and restoration efforts for shoreline areas of the lake.
Feeding, Growth, Condition and Energetics of Juvenile Pink Salmon in the Gulf of Alaska
Collaborators: K Myers (co-PI), J Armstrong, N Davis, R Walker (staff), J Moss, A Cross (graduate students)
Support: National Science Foundation
The UW School of Aquatic & Fishery Sciences will collaborate with the University of Alaska Fairbanks School of Fisheries and Ocean Sciences in a 5-year study to conduct Global Ocean Ecosystems Dynamics (US GLOBEC) funded research in the Coastal Gulf of Alaska (CGOA) component of the Northeast Pacific Program. Process-oriented studies will be conducted in two field phases (July-October 2001 and 2003) of the CGOA program. The primary goal is to understand the conditions that favor rapid growth and survival of juvenile pink salmon, Oncorhynchus gorbuscha. The major research objectives are (1) describe spatial and temporal variation in juvenile pink salmon diets and surface zooplankton abundance from Prince William Sound and the adjacent continental shelf from July-October; (2) measure prey selectivity by pink salmon as a function of size, time, and location; (3) measure growth and condition of pink salmon and relate them to prey availability and water temperatures; (4) estimate daily ration of pink salmon with field experiments and bioenergetic models; (5) evaluate spatial and temporal variation in the growth potential of pink salmon in the marine environment over the continental shelf using foraging and bioenergetic models; (6) determine the relationship between pink salmon prey use and prey use by other planktivorous fishes over the continental shelf.
Flathead Lake Food Web Modeling
Collaborators: M Hammer, N Overman (staff)
Support: Salish Kootenai Tribes
The effects of altering sportfish populations on the food web dynamics of Flathead Lake will be investigated by documenting the food habits of major consumers in the lake and using bioenergetics models to quantify these interactions within a temporal, spatial, and size-structure framework. This model will provide a tool for simulating the effects of various management scenarios on key species in the basin.
Salmon Marine Trophic Demand and Distribution in Puget Sound
Collaborators: E Duffy (graduate studnet), RL Buckley (Washington Dep. Fish & Wildlife), N Overman, C Sergeant, S Damm, A Lind, M Hammer (staff)
Support: State of Washington Office of the Interagency Committee
Seasonal diet, distribution and growth of wild and hatchery salmon, and potential competitors and predators will be examined in a food web modeling framework. This will determine whether seasonal changes in environmental conditions, food supply, or species interactions influence timing, survival or growth of juvenile salmon during their migration or residence in Puget Sound, and help managers develop appropriate hatchery-wild salmon management strategies.
Implications of Alternative Energy Pathways and Environmental Conditions on Ecosystem Dynamics and Salmonid Recovery in Lake Washington-Sammamish
Collaborators: MM Mazur, J McIntyre, H Berge (graduate students), N Overman, C Sergeant, M Hammer, S Damm, A Lind, M Grassley (staff)
Support: King Co. Dep. Natural Resources, Seattle Public Utilities
A food web model will be constructed for the upper trophic levels (zooplankton through top predators) of Lakes Washington and Sammamish. We will synthesize existing information with current field data on food web interactions of the primary native and nonnative salmon and associated species in a stage-specific, temporal–spatial modeling framework to examine potential system responses to changes in fish or invertebrate populations or environmental conditions. By using this approach, we will identify and quantify factors contributing to the decline, or inhibiting recovery, of ESA-listed salmonids (chinook Oncorhynchus tshawtyscha, kokanee O. nerka, bull trout Salvelinus confluentus), sockeye salmon (O. nerka), and other important species. This will provide the ecological context for evaluating potential trophic responses of these species to proposed wastewater treatment alternatives in the basin.