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NOAA indicators show improving ocean conditions for salmon

July 20, 2007 Fish and Wildlife Columbia Basin Bulletin
Not withstanding a few "mixed signals," environmental and biological indicators charted by the NOAA Fisheries Service's Northwest Fisheries Science Center portray an ongoing transition to conditions off the Oregon and Washington coasts that bode well for salmon survival and growth.

"Ecosystem indicators measured in 2006 point to improving ocean conditions, suggesting higher adult returns of coho salmon in 2007 and spring Chinook salmon in 2008," according to "Indicators Update: Spring 2007." The NWFSC product was posted online last week: http://www.nwfsc.noaa.gov/research/divisions/fed/oeip/a-ecinhome.cfm

Those mixed signals, however, and the project's focus on just a portion of the salmon life cycle, temper the forecast.

"Taken together, our indicators suggest that adult returns of coho in 2007 and spring Chinook in 2008 will likely be near to, but slightly below, returns averaged over the past decade," the report says. The project, "Ocean Ecosystem Indicators of Salmon Marine Survival in the Northern California Current," plans to update the forecasts each year after data is refreshed each June and September.

The indicators note shifting water temperatures and conditions and the potential availability of food resources for the salmon. June data collection tells the physical condition of the ocean and September scientific sorties offshore add to the picture with biological conditions such as food availability and predator population status added to the equation.

The goal of the forecasting project unveiled last year is to provide a snapshot of what the yearling salmon experienced when they left freshwater and entered the Pacific Ocean. Its forecasts are qualitative rather than quantitative, rating future returns as good, intermediate or poor, rather than making numerical predictions.

"In that context we were right on," Ed Casillas, the NWFSC's Estuarine and Ocean Ecology Program leader, said of initial forecasts produced last year that predicted below average 2006 coho and 2007 spring chinook returns.

"We don't want to get into that numbers game," Casillas said, because of the "other forces that affect that return." The young fish eventually disperse from the study area, growing to maturity in different parts of the ocean and experiencing varying conditions.

The data used has been retrieved by NWFSC since 1996 off the California, Washington and Oregon coasts. The California Current is a "broad, slow, meandering current" that flows south from the northern tip of Vancouver Island to Punta Eugenia near the middle of Baja, California, and extends laterally from the shore to several hundred miles from land.

"It doesn't capture anything beyond that first summer," Casillas says of the study/forecast. The data tool is designed to complement other forecasting indicators, such as jack returns, smolt-to-adult return rates (Scheuerell and Williams 2005), and the Logerwell production index.

None of the existing forecast tools solves all of the deep-sea survival mysteries. As an example, the researchers run a trawling operation off the Oregon and Washington coasts in June and September in an attempt to assess the relative abundance of chinook and coho that had survived to that point.

The June 2005 trawl netted the fewest juveniles since that operation began in 1998. It was followed in 2006 by the lowest upriver spring chinook jack return to the Columbia since 1998. The 2007 upriver spring chinook return -- featuring 4-year-olds from that 2005 outmigration -- was the lowest since 1999.

In June 2006 the trawlers netted considerably more juvenile chinook, though still less than the average over the course of the study. That's one signal that the 2007 jack and 2008 adult returns could increase.

The actual upriver spring chinook "jack" return this year from that 2006 outmigration skyrocketed with Bonneville Dam counts the third-highest ever recorded on the University of Washington's DART web site -- after 2000 and 2003.

"They're higher than we would have predicted," Casillas said. The jack counts are strong indicators but do not foretell the magnitude of the next year's return. The 2000 record jack count, 21,000, was followed by a record adult return of more than 400,000 upriver spring chinook. The 2003 jack count was more than 14,000, and was followed by an adult return of 190,000. That was a relatively high return but undershot numerical preseason forecasts, which were based in large part on the previous year's jack counts, that year by nearly 50 percent.

This year's jack count was similar to that of 2003.

The trawling picks up coastal coho stocks, as well as from the Columbia River, Washington coast, the Puget Sound and Vancouver Island with the Columbia stocks representing about half of the total, Casillas said. Likewise, upriver Columbia River spring chinook stocks represent about half of the catch that includes fall chinook from the basin that are released as yearlings.

The NWFSC researchers use three sets of indicators in an attempt to better understand the interactions among juvenile salmon and their environment. The first is based on large-scale oceanic and atmospheric conditions in the North Pacific Ocean, and consists of the Pacific Decadal Oscillation and the Multivariate El Niño Southern Oscillation Index.

The second set is based on local observations of physical and biological ocean conditions off Newport, Ore. The third set is based on biological sampling of plankton, juvenile salmonids, forage fish, and Pacific hake off the coast as part of a Bonneville Power Administration-funded research program.

Each of the variables within those sets is ranked each spring and fall -- good, intermediate or poor.

The data collected last month was almost universally "good" with the PDO getting the only intermediate rating among the 11 variables assessed. That means the spring chinook that would begin returning as adults in 2009 likely met favorable conditions upon entering the ocean this year.

"Cold" oceans conditions -- cooler than average -- are generally considered good for chinook and coho while warm conditions are not.

"The year 2006 marked what now appears to be the beginning of a transition from the poor ocean conditions observed in 2004-2005 to very good conditions in 2007," the report says of the PDO, climate index based upon patterns of variation in sea surface temperature of the North Pacific.

A warm-phase PDO prevailed during most months from August 2002 through July 2006, but since July 2006, PDO values have either been negative or near zero. A PDO of zero indicates a neutral state, which suggests "average" ocean conditions. A "warm ocean" trend in more localized Sea Surface Temperatures began in November 2002, but abated from late 2005 through early 2006.

"From June 2006 to May 2007, cooler-than-normal SSTs have been observed in the coastal upwelling zone. Therefore, implications for salmon survival are 'mixed' in terms of SST -- warm SSTs in early 2006, when salmon first went to sea, were a negative indicator, but cooler SSTs, which have continued into 2007, are a positive sign," according to the report

"Local ocean conditions reflect theses changes, with coastal upwelling and the physical spring transition date creating conditions that should benefit salmon survival.

That transition included a bit of a hiccup last year, causing some uncertainty about the fate of the young coho and chinook that went to ocean. The annual upwelling of nutrients began in early May, but atmospheric conditions changed drastically after just two weeks. Strong southwesterly storms moved up the coast and "may have erased or 'reset' any signature of upwelling."

As a result the so-called biological transition -- the appearance of the kind of food chain that coho and chinook salmon seem to prefer -- did not occur until May 30.

The latest report also does not capture poor ocean conditions that prevailed from April through mid-June, 2006.

"Thus, salmon encountered poor ocean conditions during their first weeks in the ocean, which likely had a negative impact on survival," the report says. The researchers plan to subdivide the data for future reports, characterizing ocean conditions in late winter/early spring and from June or July through September, when salmon that survive ocean entry experience rapid growth.

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