Water Stewardship Information Sources
| Citation | Johannes, MRS et al. 2011. Technical Report 12 - Fraser River sockeye habitat use in the lower Fraser and Strait of Georgia. Cohen Commission Enquiry. |
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| Organization | Cohen Commission |
| URL | https://www.watershed-watch.org/wordpress/wp-content/uploads/2011/07/Exh-735-NonRT.pdf |
| Abstract/Description or Keywords | There is a general view that Fraser River sockeye face a series of challenges and issues which have influenced freshwater and marine sockeye growth and/or survival over at least the past two decades. The lower Fraser River and Strait of Georgia (also known as the Salish Sea) continue to be centres of human activity and development which have changed the natural landscape and potentially altered the extent and characteristics of sockeye habitats. Salmon are often viewed as a living barometer of the conditions in the environment and their habitat state and stock status could reflect potential impacts from human activities. As part of the Cohen Commission’s inquiry, a series of twelve technical reports have been developed to address potential issues identified during the first phase of the Commission’s work as being possible causes of an observed long term decline in the production of Fraser River sockeye. The objective of these technical reports has been to explore causal hypotheses related to the observed declines. Within this context, the primary objective of the technical report presented here is to review and summarize potential human development-related impacts over the recent 1990 to 2010 period and to examine potential interactions between human development and activities in the lower Fraser River and Strait of Georgia and Fraser sockeye salmon habitats. Many of the issues and potential interactions between human development and their impacts summarized in this report could potentially apply to other species of wild salmon or other species of fish as well as their habitats; however, the evaluation of effects in this report is focused on Fraser sockeye. The population of British Columbia has grown to more than 4 million people in 2005 (census data), with 3.2 million people living in urban areas concentrated around the lower Fraser River and the Strait of Georgia. Over the past century, land and resources have been developed and exploited throughout the lower mainland of BC (Fraser Valley and Fraser Delta areas) and the Strait of Georgia for housing, industry, infrastructure, transportation, forestry, agriculture and mining. Many of these activities are near or adjacent to the lower Fraser River and in urban and industrial centres along shorelines around the Strait of Georgia and thus have the potential to interact with the habitats used by sockeye. The Fraser River and the Strait of Georgia both have significant value for human use as commercial, recreation and transportation corridors and as receiving areas for wastewater, along with other human-related functions like water supplies, recreation, irrigation, and fisheries. The factors used to examine changes in the level of human activities and or possible outcomes of those activities included: population (size, density), land use (agriculture, forestry), large industrial and infrastructure sites and projects, waste (liquid and solid waste), shipping vessel traffic, lower Fraser River dredging and diking, and the Strait of Georgia biological and physical water characteristics including non indigenous (invasive) species and human derived contaminants. The approach and methods used to identify and define interactions and analyse their potential extent or overlap between human activity and sockeye habitats reflects a similar process to that used in environmental impact assessments. Key Findings Our review suggests that Fraser sockeye use specific or key life-history-related habitats with different residence periods (extent of habitat use over time), in both freshwater and marine areas of the lower Fraser and Strait of Georgia. The Strait of Georgia and the lower Fraser River are used by both juvenile and adult sockeye salmon as key habitats and migration corridors on their way to and from the North Pacific. While this may not be the case for some other Pacific salmon species, freshwater and marine habitats used by sockeye often have short residence periods (days); with the exception of incubation in freshwater spawning habitats and rearing in lakes (months to years). In the ocean, sockeye exhibit large annual and seasonal variation in spatial distribution dependent on marine water properties encountered and on preferred prey distribution and abundance. Results from other commission technical reports, our information review and examples from the literature suggest the annual variation in the quality of these conditions (water properties and biological characteristics) may have important links and potential effects on sockeye production. Juvenile sockeye in the Strait of Georgia appear to be particularly sensitive to changes in growth experienced during cool productive and warm unproductive conditions related to prey availability, surface currents and swimming speeds, and potentially to competitors and predators. |
| Information Type | report |
| Regional Watershed | Lower Fraser |
| Sub-watershed if known | Fraser River |
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| Project status | complete |
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