Shifts in sockeye salmon productivity in freshwater:
interactions between climate change and stream habitats
Doug Braun and John Reynolds
Background
Climate change can lead to shifts in
productivity of populations, altering
their dynamics. Few studies are able
to observe such shifts because of
limited population time series data.
Even for Pacific salmon populations,
where long-term population estimates
exist, most models fail to capture
climate-driven shifts in productivity.
Furthermore, little is known about how
local habitat characteristics may buffer
or magnify effects of climate change
on individual populations.
Study Sites
Methods
1. Develop spawner-recruit relationships
using a Kalman filter estimation
procedure
Sockeye population data - 1938present
Kalman filter estimates productivity for
each year
Individual populations and population
complex level
2. Add climate variables to population complex level spawner-recruit
models
Fort St. James weather station data - 1895-present
Temperature - daily min, max and mean
Precipitation - total rain, total snow, snow on ground
3. Add local habitat variables to individual population level spawner-recruit
models
Stream habitat data collected in 2007-present
e.g. stream temperature, shading, gradient, water discharge,
habitat types, stream size
Fort St. James Air Temperature
Hypothetical relationship between air
and water temperature for two streams
Implications
Use key stream habitat
characteristics to identify streams
sensitive to climate change
Understand how changes in
environmental conditions influence
sockeye salmon population
dynamics during their freshwater
phase
Can model future impacts of climate
-Spawning salmon experience warm water in the
summer
-Incubating embryos experience cold water over
the winter
change and habitat alteration on
Pacific salmon populations
Water
Temp
Research Objectives
1) Understand how climate influences
the productivity of individual sockeye
salmon populations and population
complexes
2) Identify local stream habitat
characteristics that mediate changes in
climate
Air Temp