Fraser River sockeye salmon: data synthesis and cumulative impacts

Fraser sockeye salmon habitat analysis: Lower Fraser River & Straitof GeorgiaMark Johannes, Golder AssociatesThe study objectives included developing an inventory of sockeye habitats in the Lower Fraserand Georgia Strait; identifying potential human factors affecting habitat and potential links oroverlaps between human development and key sockeye habitats/habitat use; summarizing thebiophysical and water quality characteristics in Georgia Strait that relate to sockeye habitat use;identifying habitat protection approaches; and reporting on linkages between Fraser sockeye andhuman development activities.The approach included identifying key sockeye habitats in the Lower Fraser, the estuary andGeorgia Strait, along with indicators of anthropogenic change and of biophysical characteristicsand change in the Strait of Georgia over the study period (1990-2010). A key metric was the lossor degradation of key sockeye habitats.Inventory of key sockeye habitats: This was based on Fraser sockeye habitat use at differentlife history stages. During their out-migration, most sockeye smolts move very quickly throughthe Lower Fraser. Some use very specific habitats, such as the brackish areas just below Hopeinstead of the real estuary, where they develop energy stores before they head out. They use theshelf areas of Georgia Strait and travel around both sides of Texada. They also use the 10 – 15metres of water.Human development: GVRD is growing the fastest of all the urban centres – and populationgrowth can affect habitat quality. Data was also examined for other indicators, including thenumber and location of large projects over time, agricultural land use, changes in forestharvesting, Lower Fraser dredging and shipping (the only increase is cruise ships) – no evidentlinks.Strait of Georgia biophysical and water quality indicators included SST, suspended solids andchlorophyll, with the information compiled in a database that breaks the data down by timeperiod over the summer. Information on invasive species and harmful algae blooms likeHeterosigma was also compiled. Sampling for Heterosigma is principally associated withaquaculture so there is a need to investigate whether the location of blooms overlaps withsockeye habitat areas.Management: Habitat and management practices are improving but there is a higher volume ofeffluent discharges simply due to the magnitude of population growth. So this needs to be pulledout.So far, initial findings appears consistent with the PSC paper, though more work still needs to bedone. It’s unlikely however that freshwater habitat conditions in the Lower Fraser River havechanged enough during the study period to affect sockeye.Evidence gaps: There are few if any consistent time series for indicators, no clear indicators ofhuman development and limited consistent indicators of biophysical conditions in the Strait ofGeorgia. The hope is to develop a better information base so that we are not just makingcircumstantial arguments about associations. We’re still quoting good work that was done 2 – 3decades ago. We haven’t yet seen Beamish’s trawl survey data. The hope is to get thecharacteristics of good sockeye habitat so that we’re not looking all over the place.59