Ocean Indicator Report Shows Conditions in 2009
Living-feeding conditions for young salmon took a turn for the worst in that 600-mile wide swath of water off the Oregon and Washington coasts called the California current, according to NOAA Fisheries Service scientists.
"During the second half of 2009, the trend of cold ocean conditions that began in 2007 and continued through 2008, changed noticeably," according to "Ocean Ecosystem Indicators 2009," according to the annual update for a research project ongoing since 1996. "After June, the ocean began to warm significantly, leading to detrimental changes in the pelagic food web and likely high mortality of juvenile salmonids."
The shift doesn't bode well for returns of coho salmon to the Columbia River basin this year. But researchers say the conditions in 2007-early 2008 should help swell spring chinook returns this year and next.
The project, "Ocean Ecosystem Indicators of Salmon Marine Survival in the Northern California Current," is a product of NOAA Fisheries' Northwest Fisheries Science Center Fish Ecology Division. The update and related information can be found at: www.nwfsc.noaa.gov/research/divisions/fe/estuarine/oeip/index.cfm
The researchers sample a number of physical, biological and ecosystem indicators to specifically define the term "ocean conditions." They use the data collected to forecast the survival of salmon that begin returning 1, 2 and 3 years later.
The forecasts are qualitative in nature, with each of the 18 ocean indicators rated "good," "bad" or "neutral" relative to their expected impact on salmon marine survival.
The biological indicators measured for the study are those encountered by salmon during their first year at sea through food-chain processes. The biological indicators, coupled with physical oceanographic data, "offer new insight into the mechanisms that lead to success or failure for salmon runs," according to the NWFSC.
"The ocean is not so much of a black box anymore," said NWFSC researcher Bill Peterson.
The overall score for the indicator data in 2008 was the best ever measured in the 12-year history of the study and those conditions lingered, for the most part, into 2009. But many of the ocean conditions changed drastically about mid-year in 2009.
"It doesn't look good," Peterson said of conditions at year's end that left 2009 conditions as the seventh best recorded by the researchers, despite the strong start.
"Poor ocean conditions during 2003-2006 began to improve during 2007 and greatly improved during 2008," the update says. The most negative winter Pacific Decadal Oscillation since 2000 and most negative summer PDO since 1955 were seen in 2008.
The PDO is a climate index based upon patterns of variation in sea surface temperature of the North Pacific. A negative or cool phase PDO is generally considered to benefit salmon. Likewise a cool El Nino/Southern Oscillation pattern is believed to help boost salmon survival. Both the PDO and ENSO turned from good to bad last year.
The PDO typically over the long-term past have persisted in cool or warm phases for decades at a time. But in recent years time spans for either phase have been much shorter, sometimes just a year or two.
"It's misbehaving. It hasn't settled into a nice regular pattern," Peterson said. "We need more (cool) years if we're going to build up salmon populations."
"Also in 2008, we observed the coldest winter sea surface temperatures of the past 12 years (and probably since the 1970s) and the earliest biological spring transition and highest northern copepod biomass of the past 13 years," according to the update posted on line this week by the NWFSC. "The latter included an anomalously high biomass of the large, lipid-rich subarctic copepods" that bolstered the food chain.
"During the first half of 2009, the PDO initially continued the same trend observed in 2008, that is, a strongly negative signal through winter and spring. However, the strong negative PDO began to weaken in June and abruptly turned positive in August."
"Based on superior ocean conditions during spring-summer 2008, we expect spring chinook runs in 2010 to rival the high returns of this species seen in 2001 and 2002," the update says. The two highest spring chinook returns on record were in 2001 and 2002. "This was our forecast last year based on ocean indicators, and our expectation is now supported by high returns of spring chinook jacks in fall 2009," the update said. Jacks are spring chinook that return after only one year in the ocean.
"We should still see a pretty good return next year," Peterson said.
"However, expectations for returns of coho in 2010 are considerably lower due to warm sea-surface conditions throughout August 2009 and low catches of coho salmon in our June and September surveys," the update says.
The low juvenile coho count during the trawl surveys may stem from a dramatic cessation of upwelling in late summer that stopped the flow of cool water and nutrients to the surface.
The annual transition to coastal upwelling began early, March 23, but "winds were weak and inconsistent, especially after May. An early start to the upwelling season is a necessary condition for good survival; however, despite the early start of the 2009 upwelling season, upwelling was weak, and had ended by early September," the update says.
The researchers theorize that warm conditions may have led to the demise of young coho, which reside in the upper few meters of the water column.
"It just stopped," Peterson said of the unusually curt end to coastal upwelling season. "That's what hurt the catch" of juvenile coho in September.
The metrics monitored by NWFSC researchers include large-scale ocean and atmospheric indicators such as the PDO and ENSO 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.
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