Nature tweaks our noses yet again

Nature, the old saying goes, abhors a vacuum.

To which we'd add: Nature also really hates it when people smugly assume something is fact.

Consider, for instance, sockeye salmon in the Columbia River.

Salmon of all sorts, with a few exceptions, have suffered greatly in the Columbia over the past couple decades. Several runs of the anadromous fish, along with their cousins the steelhead, have been listed as threatened or endangered since 1991.

The sockeye, though, was first such species to warrant federal protection, and the one that has fared worst.

Until this year.

So far this year about 215,000 sockeye salmon have returned to the Columbia, more than in any year since 1955.

The twist in this story is this: No one knows, with absolute certainty, why the sockeye population this year is so plentiful.

Some biologists contend this year's bountiful sockeye run is the result of a federal court order that required dam operators to release extra water in 2006 and 2007 to "push" juvenile sockeye downstream to the Pacific.

Other experts point out that conditions in the ocean have been better suited to sockeye survival the past couple years, and hatcheries released more sockeye in those years.

The bottom line, though, is that this year's sockeye success refutes with raw numbers the notion, which has become nearly universal among the scientific community, that salmon are basically doomed due to the gantlet of dams, commercial fishing, and predators such as northern pikeminnows and sea lions.

That notion might, of course, be proved accurate.

Chinook salmon have returned in huge numbers in a couple recent years, too, but then plummeted the very next year.

Hatchery-raised fish in particular, which usually constitute the majority of Columbia runs, seem vulnerable to minor changes in river and ocean conditions.

There's certainly no definitive, long-term evidence that tinkering with the Columbia — dumping extra waters from the reservoirs, for instance — can completely offset the harm those concrete impediments pose to fish whose survival depends absolutely on their ability to navigate hundreds of miles of river.

Nonetheless, this year's sockeye salmon run ought to remind all of us that not everything we're so sure we know to be true, necessarily is.

And more to the point, some of our most persistent problems, such as Columbia River salmon runs, might not be beyond solving after all.