[env-trinity] CBB: Ocean Indicators Efforts Leading To More Certainty In Predicting Annual Salmon Returns
sari at sisqtel.net
Fri Dec 17 15:27:05 PST 2010
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 weve 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.
Were 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.
Its 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.
Thats where theyre 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 NWFSCs 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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