Graduate Thesis Or Dissertation
 

Anthropogenic activities associated with the status of salmon stocks in Pacific Northwest watersheds

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  • Stocks of salmon are declining in the Pacific Northwest. Based on region-wide studies that list and categorize the status of salmon stocks (Nehlsen et al., 1991; Huntington et al., 1994; and Nawa, 1995), I analyze the watersheds where stocks of salmon spawn for several anthropogenic variables, most of which are known to affect salmon. A total of 202 watersheds (stocks of salmon) in Washington, Oregon, California, and Idaho are coded for 13 anthropogenic variables such as dams, forest, agriculture, human population, hatcheries, Indian tribes, and watershed organizations. Most variables are ordinally coded 1 to 5 with the help of maps, some survey results, and visual assessment. Hypotheses are that the human activities that are detrimental to the health of salmon are associated with the poor status of salmon stocks in watersheds where they spawn. Salmon watersheds are also analyzed according to ecoregions and salmon management regions. Principal components analysis is performed to reduce the number of anthropogenic variables into factors. Kendall's tau, partial correlation, multiple linear regression, logistic regression, and discriminant analyses are performed separately for five species/races of salmon (coho, spring chinook, summer chinook, fall chinook, winter steelhead) and for the watershed average for salmon stock status, against the anthropogenic variables and factors. Statistical results using both variables and factors support most of the hypotheses relative to salmon and anthropogenic activities in watersheds. Results suggest that the 5 species/races of salmon are associated differently with most anthropogenic activities. The greater the amount of dams below watersheds where salmon spawn, the less healthy the salmon stocks. Summer chinook are least healthy where hatcheries are absent, while wild and scenic rivers are associated with healthier spring chinook. Coho are least healthy where there is more agriculture, more human population, and less forest. Fall chinook are least healthy where there is more US Forest Service land. Winter steelhead are least healthy where hatcheries are absent and less Indian tribal land. Ecoregional differences coupled with the absence of dams on the Coast compared to the Columbia Basin are associated with healthier coastal stocks.
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