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Ocean 'indicators' help develop forecasts


The Columbia Basin Bulletin
March 20, 2009

All of the signs -- called ocean indicators -- point toward swelled returns to the Columbia River basin in 2010 and 2011 that could even challenge 2001's record upriver spring chinook salmon run, according to ongoing research conducted by NOAA Fisheries Service's Northwest Fisheries Science Center.

"The ocean was chockfull of food" in 2008 when juvenile salmon emerged from the Columbia to start their ocean sojourn, the center's John Ferguson told the Northwest Power and Conservation Council last week.

Ferguson, head of the center's Fish Ecology Division, was among those on a panel assembled by the Council to discuss "Status of Adult Salmon Runs, Ocean Conditions and Mainstem Passage." He briefed those in attendance on the effects of changing climate and ocean conditions on fish populations and on the evolving "Ocean Ecosystem Indicators of Salmon Marine Survival in the Northern California Current" project.

NOAA researchers have since 1996 collected physical and biological ocean data during research cruises to study the coastal upwelling ecosystem off the Pacific Northwest. The data is used to develop environmental indicators to help forecasts of salmon returns.

They include the status of large-scale ocean and atmospheric indicators such as the Pacific Decadal Oscillation and the El Nino Southern Oscillation Index and local and regional physical indicators such as sea surface temperature, coastal upwelling of nutrients, the strength of the springtime transition to upwelling and deep-water temperature and salinity.

Biological indicators include measures of the quality and quantity of organisms that build the near-shore food chain and the actual netting, and counting, of young fish. Juvenile salmon caught during June and September trawl surveys off the coast serve as an index or surrogate measure of ocean survival for spring chinook and coho salmon.

The June 2008 trawls for chinook were "the best that we've seen," Ferguson said.

The counts were "literally off the charts" kept over the 11 years of the study. The catch of more than 40,000 juvenile chinook last year was more than double that of 1999. The catch per unit of effort, 2.55, was also double the next best catch rate in 1999. Those smolts caught in 1999 contributed to the banner 2001 run.

"Every time we put the net in the water we caught salmon," Ferguson said.

The other 10 indicators showed favorable conditions for the young chinook as well. Each of the conditions measured is rated red, yellow or green - bad, intermediate or good conditions for salmon survival. Never before has there been a green sweep of the rating's chart.

"2008 was comparable to 1999," Ferguson said.

"We expect spring Chinook runs in 2010 and 2011 to rival the high returns of this species seen in 2001 and 2002; however, expectations for returns of coho in 2009 are somewhat lower due to warm sea -- surface conditions throughout August and low catches of coho salmon in our September 2008 survey," according to the ocean indicators January forecast.

"The other 10 indicators are green" for coho, Ferguson said, which means that their return of this year should be strong as well.

Some chinook return this year as jacks, but the bulk of 2008's outmigrants that survive would return the following two years.

The 2001 return actually overperformed in comparison the projections of the science center's April and September upwelling and downwelling statistical modeling.

Based on 1999 ocean indicators, the center predicted the smolt-to-adult return would be 1.49 percent, the midpoint in a range of from 0.34 to 3.45 percent. The 2001 upriver spring/summer chinook return, which included 2-ocean fish from the 1999 outmigration, had a 3.56 percent SAR with 415,000 counted passing Bonneville Dam on the lower Columbia and 172,000 reaching the lower Snake River's Lower Granite Dam, the eighth and final hydro system hurdle on their spawning run.

Modeling done last year predicts 2010 spring chinook SAR will be 1.56 percent. Only time will tell what the actual return will be.

"We're looking forward to that," Ferguson told the Council.

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