Sea Lions Split for the Season
by Bill Rudolph
NW Fishletter, June 19, 2009
As the spring chinook season tails off into summer, most of the salmon-munching sea lions at Bonneville Dam have taken a powder and are heading for breeding grounds off Southern California and Baja.
The number of the marine mammals sighted near the dam has plunged into single digits from the nearly four dozen counted April 22, split nearly evenly between California and Stellar sea lions.
"It is very likely the removal program by the states is a major reason for the decrease in California sea lion presence," according to a May 22 report by the Corps of Engineers.
Ten were euthanized, four were relocated to zoos or aquariums, and eight others were tagged with acoustic transmitters and released.
The report said that average daily number of California sea lions was about 10, the lowest since 2004. Fifty-three different individuals were identified, with 19 visiting Bonneville's salmon smorgasbord for the first time.
Biologists said that predation figures will be lower than last year and about equal to 2007. With a larger spring chinook run size this year, the mammals' percentage take was slightly above 2 percent, though the actual numbers consumed may be the second or third highest of the past eight years.
The report also noted that on May 22, a California sea lion was riding on the stern of a tug through the lock at Bonneville Dam, heading upstream. The creature hasn't been seen since.
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