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Where Have All the Salmon Gone? Graphing Results Fish Catch on the Columbia River 35 30 Millions of pounds 25 20 1-Chinook 2-Coho 3-Chum 15 4-Sockeye 5-Steelhead 10 5 0 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 Decades 1880s: Canning of Chinook increases 6x First 35 attempts to regulate fishing 30 1930s-50s: logging increases in lower river system World War I 1930s: Bonneville Dam is built 1950s: 8 new dams built 20 15 Canneries start using other fish species 10 1980s: Regulations ban ocean catch of Chinook, Coho Regulations: only gill netters allowed on river. 25 Millions of pounds Fish Catch on the Columbia River 1920s: First ocean trawlers 5 1940s: 4 new dams built Nitrogen supersaturation around dams kills small fish 1960s-80s: Hatchery techniques improve 0 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1866: First fish cannery Decades 1950s: massive hatchery program 1-Chinook 2-Coho 3-Chum 4-Sockeye 5-Steelhead On the back of your graph: • What advantages and drawbacks are there to using fish catch data as a way of measuring salmon populations? • Which human-caused factors had the most effect on salmon populations? Why? • Should salmon recovery efforts focus only on habitat restoration, only on reducing fishing and predation, or both? Why? Find and cite a section in your textbook that supports your answer.
