[env-trinity] CBB: Ocean Indicators’ Efforts Leading To More Certainty In Predicting Annual Salmon Returns

[Sari Sommarstrom]

But what about predicting how well the Klamath 
River's young salmon fare in the ocean? Is the 
science getting more certainty here also, and not just the Columbia River fish?

  ‘Ocean Indicators’ Efforts Leading To More 
Certainty In Predicting Annual Salmon Returns
THE COLUMBIA BASIN BULLETIN:  Weekly Fish and Wildlife News  www.cbbulletin.com
December 17, 2010  --- Issue No. 556

Fifteen years of monitoring a suite of 16 
physical, biological and ecological “indicators” 
of ocean conditions has left NOAA Fisheries 
scientists confident they could now predict with 
reasonable certainty how young salmon from the 
Columbia River might fare during their first few months in the Pacific Ocean.

“We feel like we’ve kind of got it figured out
 
except for this year,” said Bill Peterson, a 
senior scientist and oceanographer with NOAA 
Fisheries’ Northwest Fisheries Science Center.

After years of collecting, analyzing and summing 
up indicator data, researchers began issuing 
forecasts about relative strength of salmon runs 
in the years to come. The forecasts are based on 
the ocean conditions the fish had encountered 
when entering the ocean as juveniles.

The NWFSC scientists have a seen strong 
correlation between highly ranked years 
(favorable indicators) and strong coho and spring 
chinook adult returns one and two years later, respectively.

In 2008, as an example, the average rank (each 
indicator is ranked poor, good or average each 
year) was the best in a 12-year data set. The 
return of coho last year was the fifth highest 
since 1970; and the upriver spring chinook was 
the third best since at least 1980.

The ocean signals measured this year were all 
over the board, though most were at the low end 
of the 12 years of rankings. And some went from 
very bad to great in terms of how they are 
believed to affect young salmon. The average of 
all 16 indicator rankings combined for this year is ninth best out of 12 years.

“2010 was a very confusing year,” Peterson told 
the Northwest Power and Conservation Council 
during a Wednesday presentation in Portland. He 
and others involved with the project are still 
trying to figure out what to make of it, and 
produce forecasts for the 2011 coho return and the 2012 spring chinook run.

“We’re going to see this year what drives the system,” Peterson said.

Cold is good when it comes to salmon survival and 
growth in the California Current that runs, 
sometimes northward and sometimes southward, along the coast.

“It’s not just the temperature itself,” Peterson 
said. “A different kind of water comes to the 
coast” when a cold period is in place and the 
current shifts in spring to bring water from the 
north that brings foodstuffs and produces an 
upwelling of nutrients to fuel the food chain.

Coldwater copepods swept down from the north are 
larger than their warmwater cousins from the 
south and literally build stores of lipids or 
fats. They in turn add a rich source to the food chain.

A southward current “fills this food chain with 
real nutritional stuff,” Peterson said.

A fortified food chain is beneficial to the young 
salmon in a couple ways. Food is more plentiful 
for them and helps fill up fish that would eat the juveniles.

The juvenile salmon have two missions in life, 
Peterson said. No. 1 is “find something to eat, 
and the other is to not be eaten. They live a simple life.”

There are four physical factors that affect 
plankton, food chains, pelagic fish and the 
growth and survival of salmon in the northern 
California Current, Peterson said. They include 
large scale water circulation patterns, that 
season reversal of coastal currents, coastal 
upwelling and the phase of the Pacific Decadal 
Oscillation ­ warm (bad for salmon) or cold.

2010 proved to be a transition year with “El 
Nino” conditions, which are generally a negative 
influence on salmon, holding sway until June 
before a shift to cold La Nina conditions. 
Likewise the PDO, a climate index based upon 
patterns of variation in sea surface temperature 
of the North Pacific, shifted strongly into a 
cold phase. Its ranking changed from the eleventh 
worst in the data set for December-March to the third best for May-September.

“In July, just like that, the ocean went cold,” 
Peterson said. “Conditions (for young salmon) 
were great later on” in the summer. The jury is 
still out on whether or not enough of the fish 
lingered long enough in the current that runs up 
and down the continental shelf long enough to receive a benefit.

Strangely enough, the sampling of juvenile 
chinook with a trawler at various sites off the 
Oregon and Washington coasts during May and June 
produced relatively strong numbers ­ the fifth 
highest. September trawling for coho, however, 
netted the eleventh ranked class in the date set.

The years of trawling has revealed that the 
juvenile coho and yearling chinook remain for a 
time in the shallower waters above the 
continental shelf. Sampling off the shelf has 
produced very few fish, Peterson said.

“That’s where they’re living, right in close.”

The research involves long-term monitoring of 
climate conditions, hydrography, zooplankton 
(copepods) and juvenile salmon abundance. The 
indicators are based on physical factors such as 
the state of the PDO, sea surface temperature, 
timing of the initiation of upwelling and 
strength of upwelling, along with biological 
indicators that index the quality of food within the food chain.

The time of the start of upwelling this year 
(July instead of April or May) and its duration 
(likely short because of its late start) were 
also well down on the chart in 2010, both ranked as the 11th best out of 12.

“The earlier the transition comes, the more 
upwelling there is..., Peterson said.

More information, go to NWFSC’s website at 
http://www.nwfsc.noaa.gov and click on “Ocean 
Conditions and Salmon Forecasting” in the box on 
the right-hand side of the page.

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