I read years ago that your chance of winning the Megabucks lottery prize was less than your chance of being attacked by a shark in the Willamette River. Now that the river is clean enough to swim in, I gotta know: Do sharks really swim up that far?—Jabberjaw
According to the Shark Research Institute, there have been 29 shark attacks in Oregon since 1974. None took place in the Willamette. Since at least a few people have won the Megabucks jackpot in that time, I'm inclined to call B.S. on your statistic. (See how I didn't say "bullshit"? That's in case I really need to swear later.)
The nearest to Portland that anyone has even seen a shark was on the Columbia River 8 miles west of Astoria (a locale you could be forgiven for misidentifying as "the Pacific Ocean"), so the chances that even a cuddly, non-biting vegetarian shark has made the 100-mile voyage are remote.
However! In 1931, a young killer whale did make its way up the Columbia to the Rose City. The 15-foot juvenile halted its upstream journey between two bridges on the Columbia Slough, where it remained, swimming around and spouting occasionally, for over a week.
This event pretty much brought the entire city to a standstill. Literally thousands of people lined the banks of the slough to watch the whale cavort. The Oregonian reported that every popcorn cart in the city had relocated to the scene.
Christened—adorably—"Ethelbert" by the press, the whale became a license to print money for anyone who had a big enough boat to take passengers on whale-watching excursions for 25 cents a pop.
Unfortunately, experts at the time were pretty sure that Ethelbert, denied a seafaring diet, was doomed to a slow death from starvation, and the Oregon Humane Society called for the animal to be "painlessly" euthanized, suggesting the "use of a dynamite charge to be lowered down beside the whale." (It's the Oregon way!)
But before that could happen, Ethelbert was harpooned by some jerks a few days later and wound up pickled in formaldehyde for a tourist attraction that never materialized. This is why we can't have nice things.