On June 24 and 26, 2008, inorganic fertilizer was applied to the Salmon River (Kelsey Bay), Grilse Creek, Memekay River and the White River to restore nutrients lost through decreased salmon production and to address footprint impacts as a result of BC Hydro diversion operations. Winter-run steelhead trout (Oncorhynchus mykiss) and coho salmon (O. Kisutch) are the primary target for enrichment activities on the Salmon River, although benefits are shared by many species, both aquatic and terrestrial. With the addition of the White River in 2008, summer run steelhead also benefited from stream enrichment (less than 10 east coast Vancouver Island streams have identified summer run steelhead stocks). A total of 3,910 kg of slow release fertilizer (Nutricote T40; 16-40- 0) was distributed over 11 sites in the Salmon River watershed.
Water sampling results indicate that orthophosphate and total phosphorous levels were elevated in treated reaches as compared to representative controls. Nitrogen levels were variable, but generally sufficient to support algal growth. Periphyton collector plates confirmed that chlorophyll a, used as a surrogate for algal growth, was elevated in treated reaches. Juvenile fish growth analysis from data collected in Grilse Creek further supported the above results, as steelhead fry in the enriched reach were 78% larger by the end of the growing season (95% confidence level). This is particularly encouraging as flows were above average throughout June as a result of large snow accumulations in the upper watershed. Fry emergence may have been delayed as a result of cooler water temperatures, and any early algal growth from nutrient addition would have been minimized until July.
Pellett, Kevin. 2009. Nutrient Enrichment of Vancouver Island's Salmon and Cluxewe Rivers. Forest Investment Account (FIA) - Land Base Investment Program. Forest Investment Account Report
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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