Salmon vs. Predatorsby Carlisle Harrison
Capital Press, April 29, 2005
Recent articles in the mainstream press list numerous reasons for diminishing salmon stocks, but little is said about one of the major causes - predators. As a biology major in May 1955 I had the occasion to take a field trip from Garabaldi, Ore., to Astoria, Ore. This anecdotal account might be dismissed by some but I believe a check of population records would verify what we observed.
From dawn to dark we looked for but saw no sea lions or seals. We were with instructors who knew where to look and we were biology students who knew what to look for. We were not surprised because it was believed that fewer than 2,000 sea lions existed on the West Coast at that time; 300,000 in the same area now is a recipe for disaster.
I don't know how many seals scientists thought there were at that time, but it was considerably fewer than exist today.
On this trip our professor became excited when he observed a Caspian Tern catching a smolt. He instructed those of us who were making a bird list that we should get that one on our list because we were not likely to see another. How wrong he was considering there are now thousands of these salmon predators the full length of the Columbia.
Having grown up on a salmon hatchery in the Columbia Gorge my father would frequently point out fish predators. Before this trip I could recall having seen one cormorant in my life. On this trip we saw cormorants, but they were not on every piling and rock outcropping in the river as we see now.
Last summer I witnessed how adaptable sea lions can be. In the past when a sea lion showed up you had better get your hooked salmon on board quickly or you might end up with half a fish. On two separate occasions we had a sea lion approach our boat only to have them watch until we released the exhausted wild fish. An easy meal.
Over the past 50 years fishing has been curtailed, dams have been adapted to improve fish passage, stream habitat has been improved, irrigators have given up water to enhance stream flows, logging practices have been modified while predator populations have exploded. During this time we have seen fish populations decrease in most salmon streams regardless of whether or not there were dams, irrigators or all the other human "evil-doers." Go figure.
From Center for Columbia River History
On the Columbia River
- Rock Island Dam started service in 1933,
- Bonneville Dam in 1938,
- Grand Coulee Dam in 1941,
- McNary Dam in 1953,
- Chief Joseph Dam in 1955,
- The Dalles Dam in 1957,
- Priest Rapids in 1959,
- Rocky Reach in 1961,
- Wanapum in 1963,
- Wells in 1967,
- John Day in 1968,
- Mica 1973,
- Libby in 1975.
On the Upper Columbia River in Canada
- Duncan Dam started service in 1967,
- Keenleyside Dam in 1968,
- Mica Dam in 1973,
- Revelstoke in 1984.
On the Lower Snake River in Washington
- Ice Harbor was completed in 1961,
- Lower Monumental completed in 1969,
- Little Goose completed in 1970,
- Lower Granite completed in 1975.
On the Snake River in Idaho
- Brownlee Dam was completed in 1958,
- Oxbow Dam completed in 1961,
- Hells Canyon completed in 1967,
On the Clearwater River in Idaho
- Dworshak Dam completed in 1971.
Fish Haven't Been Fighting Structures for 60 Years by Gordon Macdougall, Seattle Post-Intelligencer - 6/9/5
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