Springer Science

So what affects how fast spring Chinook blow up the Columbia? Why do they hit the big river when they do? What saltwater and freshwater cues factor into the species’ decisions? And why won’t they bite your killer cutplug?!

In recent years, scientists have been working on these questions.

Well, maybe not that last one, but what they are learning could help fishery managers make more accurate forecasts.

The latest and greatest comes from a December 2009 paper by James J. Anderson and W. Nicholas Beer of the University of Washington’s School of Aquatic and Fishery Sciences. They say that 62 percent of when a springer heads for the barn has to do with just the fish itself.

“Run timing variations were largely due to variations in the abundances of the distinct stocks comprising the runs,” they write in Ecological Applications.

Have lots of salmon from earlier- or later-running stocks and you get a return that skews earlier or later.

Anderson and Beer found that only 15.5 percent of timing depends on what’s happening out in the ocean and in the river itself. We’ll touch on the former in a bit.

THEIR WORK ADDS TO that of Matthew Keefer and other University of Idaho researchers who looked at river temperature and discharge and some cues in the Pacific.

Among their 2008 conclusions was that, generally, when the Columbia flows low and relatively warm in late winter, the 17 stocks that make up the upriver run come in earlier. And when the big crick is high and cold, those salmon come in later.

Good examples are 2001 and 2006’s springers, among the eagerest and tardiest runs in recent years.

One of the most important run-timing factors across the basin is February river conditions, Keefer et al found. It affected twice as many stocks – 10 East Cascades and Central Idaho runs – as any other single factor.

While last winter saw a mini Ice Age in Spokane – and a correspondingly cold Columbia deep into spring – this year, snowpack is lighter than normal, and ice-covered lakes were opening up in late January and early February. “Things are pointing to an earlier run this year,” said Keefer on Feb. 1.

AS FOR HOW QUICKLY springers swim upstream, in the late 1990s and early 2000s, Keefer and others at UI’s Fish Ecology Research Lab radio- and PIT-tagged nearly 3,700. They determined the salmon covered anywhere from 71/2 to 201/2 miles a day.

Different water conditions made for quicker or slower passage, anywhere from 13 to 26 days on average to go from Bonneville to Priest Rapids between 1996 and 2001, while those taking a reggie at the Snake needed 14 to 33 days to battle up to Lower Granite from Bonnie.

THIS MAP SHOWS PASSAGE UPSTREAM PASSAGE OF SIX RANDOM COLUMBIA BASIN SPRING CHINOOK DURING LAST YEAR'S RETURN. THE FISHES' PIT TAGS WERE READ AT ARRAYS ON CERTAIN DAMS AND FISH WEIRS AS THE SALMON SWAM PAST. FOR MORE ON EACH FISH, SEE THE MARCH ISSUE OF NORTHWEST SPORTSMAN. (ANDY WALGAMOTT)

Interestingly, their data also showed that springers are the slowest of the Columbia’s Chinook stocks. Summers and fall brights are slightly speedier.

“They migrate at a relatively cold time compared to summers and falls, so metabolically they can’t move as fast,” explains Keefer. They also found the later a springer gets the itch, the faster it swims – 1 to 3 miles a day faster every two weeks season progresses.

BUT LET’S GO BACK downstream, to the Pacific Ocean.

As we pointed out in a previous issue, once springer smolts leave the Columbia, they basically disappear into an ocean the size of Mars. The fish don’t turn up in commercial catches, their little PIT tags pass by no receivers, they are just somewhere … out there for one, two, even three years.

Anderson now figures that with prevailing ocean currents, it’s likely that the fish return to the Columbia from their mysterious sojourn not from the north or northwest and the Gulf of Alaska, but from due west.

He uses hypothetical fish but real magnetic keys and offshore currents to make that point. In winter off our coast, the ocean “flows” northerly, and it’s easier to swim with or across it than against it.

“It’s really kind of interesting stuff,” says Anderson.

Also interesting will be how last year’s record jack return – around 82,000 of the precocious males – will translate into adults this season. Was it a meaningless anomaly or really a sign of a fantastic number of 4-year-old fish about to make the run?

As reports of the first springers surfaced in early February, Anderson was licking his chops – and not just about what interesting data might come in.

“I eat the fish with great pleasure,” he says.

So maybe a new study on cutplugs isn’t that far off. –Andy Walgamott

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