COLUMBIA RIVER – After a spectacularly slow start, this year’s Columbia River spring Chinook run pretty much ended up as predicted, with slightly over 200,000 fish returning to the river’s mouth.

A month ago, basin fish managers upgraded their previous 203,000-fish forecast to 214,000. Their preseason prediction was about 198,000.

The managers’ preseason estimates included about 91,000 wild and hatchery spring Chinook returning to the Snake River this year, and 22,400 to the upper Columbia. At this point, about 64,000 springers have already passed Lower Granite Dam, with about 81,000 counted at Ice Harbor. In the Columbia, about 17,000 have been counted at Priest Rapids.

The Bonneville Dam count of 203,000 is the fifth highest in the past 11 years, but second highest in the past 8 years, and close to last year’s return of 277,000, which was the focus of much consternation, since the jack count from 2009 – a whopping 82,000 – would have normally signaled a much larger run than actually showed up in 2010. (Jacks are immature fish that return early to the river from the ocean.)

That 82,000-jack count would have meant a 2010 return of a million fish or so, which didn’t seem very likely. So harvest managers averaged their predictions from seven different models to estimate the 2010 return, which actually ended up about one-third shy of their 470,000-fish estimate. That would have been the largest run since 1938, when fish counters began tallying Chinook at the brand new Bonneville Dam. It would have even surpassed the 440,000-fish return of 2001.

Still, it was the third best return since the dam was built.

This year’s 67,000 fish jack return has the managers facing a similar dilemma after last year’s relatively benign 16,623 spring jack count at Bonneville. But since then, more attention has been directed at what might be behind these off-the-chart jack counts. Researchers are also taking a hard look at the increasing numbers of mini-jacks returning to hatcheries. These are young fish that return the same year they are released. In some cases, they make up to 40 percent of the returning males.

But it looks mostly like the higher jack counts come from the opportunity of young fish to grow faster in their first several months in the ocean. Perhaps they migrate to a different, sometimes more productive part of the ocean than most of the migration, Larsen speculated. But he made clear that no one really knows.

The 82,000 jacks that showed up in 2009 are generally thought to have benefited from the extraordinarily good ocean conditions off in the North Pacific, when basic productivity was the highest and the water the coldest in over 40 years. Biologists speculated that hormonal changes may have occurred in some of the young fish that did not occur in years of average productivity.

Larsen said the huge jack return this year likely means that next year’s run will contain fewer two-ocean fish than fish managers have traditionally forecast. It could mean 50,000 fewer adults next year, if those fish had matured early.

The extra puzzle this year is that when these jacks went to sea in 2010, ocean conditions were not nearly as good as 2008. NOAA ocean researcher Bill Peterson, based in Newport, Ore., told NW Fishletter that conditions for fish in the early spring of 2010 were still lousy because the region was cycling out of an El Niño event. But later in the spring season, conditions improved remarkably.

“That was something we hadn’t seen before,” Peterson said, who noted that the ocean last year was still not nearly productive enough for scientists to expect 67,000 spring jacks to return this year.

Peterson said the June 2010 trawl survey off the coast that counts juvenile salmon was nothing like the high counts seen in 2008, a year before the monstrous jack count. Last year’s survey was only the fifth highest juvenile count since NMFS began keeping track, he said, which suggested about 21,000 jacks would return this spring, not 67,000.