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Location: Fraser River Basin, Project Summary
The purpose is to examine how aspects of freshwater and riparian habitats affect salmon populations, and how adult abundance in turn affects ecosystem productivity, including potential benefits to resident trout populations. We will test quantitative links between proposed physical habitat indicators and past and current salmon abundance. We will also test quantitative links between historical and recent salmon escapement and various indicators of ecosystem health and productivity. We will use this new information to inform future management decisions aimed at improving the sustainability of wild salmon stocks, with particular emphasis on implementation of Canada’s Wild Salmon Policy. We will examine sockeye salmon populations in two regions of the Fraser Watershed: the Stuart/Takla catchment at the Fraser’s northerly limit for sockeye, and the Shuswap/Thompson catchment in the Interior. We will link data from the DFO on historical salmon population sizes to new data that a team of graduate students will collect concerning stream and riparian habitats and ecosystems. By relating differences between pairs of streams, in both physical and biotic characteristics, to differences in their salmon escapement, we will control for potentially confounding factors such as oceanic survival, fisheries mortality, differences in migratory route and lake productivity during juvenile rearing. We hope to generate a list of candidate abiotic and biotic indicators distilled from published literature, produce a summary of salmon escapement for specific reaches in our study streams, and perform statistical analyses to understand both the importance of specific habitat features for sockeye spawning populations, as well as the impacts of sockeye on stream productivity, through nutrient inputs from their carcasses. See also: Click here for more information Interim Progress In 2007 we worked in 26 streams around Takla Lake and Middle River, and 14 streams in the Thompson/Shuswap area. In these 40 streams we measured a large suite of variables, including channel morphology, water quality, substrate, large woody debris, temperature, flow, and so-on. We also collected stream invertebrates, and measured primary production in streams, and we used electro-fishing surveys in the Takla streams to quantify and measure all species of fish. Small fin clips were taken for stable isotope analyses to detect salmon-derived nutrients in resident rainbow trout as well as in their invertebrate prey, in order to test whether carbon and nitrogen from salmon are taken up by stream invertebrates, and then by trout feeding on those invertebrates. In total, each member of the team spent 150 days wearing chest waders, they took over 800 aquatic insect samples, 250 water quality samples, measured 9,000 pebbles as part of the substrate assessment, took 9,000 canopy measurements, and electro-fished a total of 7,800 m of stream! This enormous amount of data will help meet a secondary objective of the study: to design optimal sampling schemes according to budgetary and time constraints, where the costs are measured in time and money, and the benefits are measured according to ability to predict differences among streams in spawning population sizes. In early 2008 we finished the salmon escapement compilation, which was a great deal of work because we had to go to DFO’s original data sheets to match their many years of salmon counts to the specific reaches that we measured, where possible. We are currently (July) identifying the huge number of invertebrate samples that we collected, and we will soon be sending out representative specimens for stable isotope analyses. In August we will return to the streams for follow-up monitoring. The rest of the year will be spent doing water chemistry analyses, and preparations of insects, fin clips, and periphyton for stable isotope analyses. In 2009 we should be ready to start the statistical analyses, interpretations, and write-ups for recommendations for conservation and management.
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