[3] Spring Chinook Run Even Later Than Last Year

Harvest managers shut down the lower Columbia River to sportfishing last week after the upriver spring run stayed at a slow trickle over Bonneville Dam.

The managers said sport catches weren't that bad, showing some evidence of a fair number of chinook in the river. But they are concerned that the run may be smaller than anticipated, like last year's spring returns.

In 2005, the chinook numbers were almost this bad. By April 16 last year, only 851 chinook had been counted at the dam. This year it's a measly 205 fish. The 10-year-average count by this date, which includes some of the largest years on record (2001, 2002) is over 40,000 fish.

The paltry numbers last year added up to an upriver spring/summer run of about 106,000 fish, about half of the preseason estimate. Managers say they expect only 88,000 upriver chinook this spring.

Over on the Willamette, it's the same story. Only 79 fish had been counted at the falls by April 12, with a run size projected around 46,500 fish. Last year, 476 had been counted at Willamette Falls by this date, but in 2004, more than 4,500 chinook had been tallied by this time. Eventually, 61,000 chinook were counted last year, significantly lower than the preseason estimate of 117,000 fish.

Scientists say near-ocean conditions in the Pacific off the West Coast are still very wintry, with much cooler water than observed over the past several years. This could mean good news for juvenile salmon that are beginning their migration to the sea.

Warm water and lack of upwelling in recent years has reduced productivity of salmon runs. In fact, the warm currents brought with them huge schools of hake from southern California waters, which scientists think have preyed heavily upon young salmon, as well as the large schools of anchovies and sardines that have appeared off the Columbia River.

Data published last year in the journal Progress in Oceanography (Emmett et al., 2005) support earlier hypotheses by other scientists that the low marine survival of Oregon coho was due not to a lack of food, but rather to increased predator activity on salmon when the favorite foods of hake and mackerel, like sardines and anchovies, were scarce.

The paper's authors said their ocean surveys found large numbers of predators like hake in 2003, but speculated that marine survival of salmonids shouldn't be as poor as during most of the 1990s because alternative prey has remained abundant.

The West Coast hake population has grown fast from its "overfished" status a few years back, and is now being targeted by both factory trawlers and smaller vessels. In 2003, hake abundance was estimated at 3.4 billion fish, or 1.8 million metric tons.

With the return to cooler water, the hake may stay farther offshore and give the juvenile salmon a better chance of making it to the Gulf of Alaska. The latest ENSO forecast issued April 6 calls for continued cool La Nina conditions for the next one-to-three months.

Several hundred thousand juvenile spring chinook have already passed Lower Granite Dam on the lower Snake River, on their way to a more hospitable sea. It's the highest smolt estimate for this date in the past six years. Spill began there April 3 and started at mainstem Columbia dams last week. -B. R.

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