[2] Ocean Conditions Improve For This Year's Outmigration, So Far

Ocean conditions off the mouth of the Columbia River have improved significantly over last year, and that should mean better spring chinook returns two years from now, two NMFS scientists told the Northwest Power and Conservation Council.

But as far as 2007 is concerned, they don't expect much in the way of spring chinook. This year's jack counts are about 30 percent lower than last year's number, one indicator of fewer fish next year. But other factors play important roles in determining counts, said Ed Casillas, research scientist with NMFS' Northwest Science Center in Seattle.

Casillas' group studies the near ocean between Newport, Ore., and the tip of the Washington coast. Researchers trawl for juvenile salmon, measure temperatures, salinity, plankton biomass, spring wind shifts and upwelling. The group also keeps track of fish populations such as hake that eat juvenile salmon, and others like anchovies, sardines and herring that predator species may eat instead of salmon.

Another important factor, Casillas noted, is the size of the freshwater plume off the coast that's created by the Columbia River. It changes from day to day, depending on flows and wind conditions, and can play an important role in the survival of young salmonids from week to week.

Casillas said 2006 was setting up to be a positive year for salmon, but it was too early to say for sure. El Nino conditions have eased, water temperatures are considerably cooler than last year, and strong upwelling was in evidence in May, a condition that brings nutrients to the surface, a necessary precursor to plankton blooms that fuel young salmon.

Casillas told NW Fishletter that trawl surveys earlier this spring had shown some of the highest juvenile salmon numbers he's seen since his group began keeping track.

But lately, he said, the weather seems to have slipped back into an earlier mode, with prevailing southerly winds, a situation that generally puts the kibosh on upwelling. He said the scientists were going out again to survey juvenile populations again. Until he gets the results from that cruise, Casillas said he would make no prognosis on spring chinook futures.

One thing is for sure, last year the researchers encountered the fewest young spring salmon in their trawl surveys since they began the offshore project in 1998, and only about one-fourth the numbers they observed in 2004. -B. R.

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