UBC Theses and Dissertations
Wind induced entrainment in the Strait of Georgia and the possible consequences for fish survival Blackett, Andrew W.
A numerical model of the Strait of Georgia, British Columbia was used to investigate the possibility that wind induced entrainment enhances the survival of fish which spend their early lives in the area, by supplying nitrate rich deep water to the photic zone and increasing primary productivity. Historical records of winds and Fraser River discharge were used to drive the combined GF4/MULES physical/biological model, to simulate entrainment and nitrate concentration in the upper layer of the Strait of Georgia during the months April to July, from 1970 to 1988. Using linear correlation coefficients and considering various functions of the wind speed, it was found that the square of the wind speed was correlated with both entrainment and nitrate concentration. Both correlations were found to be statistically significant at the 1% level at most of the locations and times studied. Correlations were particularly strong during times that young salmon usually enter the Strait on their migration to the ocean, resulting in the conclusion that the square of the wind speed could be used as an indicator of potential food supply to the fish. Historical wind speed records were then compared with survival data for salmon and herring in the Strait. Little correlation was found between survival rates of different species, or between wind speed and survival of any species, suggesting that there are too many other factors to allow prediction of marine survival from nitrate enhancement alone.
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