[env-trinity] 2008 Ocean Conditions for Fish Among Best in Half-Century
sari at sisqtel.net
Fri Jan 2 11:27:34 PST 2009
12-18-08 OREGON STATE UNIVERSITY
2008 Ocean Conditions for Fish Among Best in Half-Century
NEWPORT, Ore. Ocean conditions during 2008 for many fish species in the
Pacific Northwest, including chinook salmon, were greatly improved because
of a huge cold water influx that settled in across much of the northern
Pacific Ocean a phenomenon not seen on this scale in years.
In fact, scientists who surveyed near-shore waters from Newport, Ore., to
LaPush, Wash., this year found the highest numbers of juvenile chinook
salmon theyve encountered in 11 years of sampling.
The reason may be traced to the
Decadal Oscillation, a pattern of climate variability that historically has
shifted between warm (positive) and cool (negative) regimes over cycles of
20 to 30 years. During 2008, the PDO was the most negative it has been
since 1955, according to Bill Peterson, a NOAA fisheries biologist at
Oregon State Universitys <http://hmsc.oregonstate.edu>Hatfield Marine
We usually see cold water conditions for a few months once upwelling begins
in late spring and early summer,said Peterson, who has a courtesy
appointment in OSUs <http://www.coas.oregonstate.edu>College of Oceanic and
Atmospheric Sciences. Since April of 2007, though, we've been in a constant
summer-stateocean condition, which is something weve never seen in more
than 20 years of sampling. And were not sure why.
Strong, continual upwelling has fueled phytoplankton growth that forms the
basis of the marine food web. Cold water has drawn a huge biomass of
northern copepods from the Gulf of Alaska, and these zooplankton species
have high fat reserves that provide a rich diet for anchovies, herring and
other baitfish, which in turn become prey for salmon, ling cod and other
is thick with these large copepods, which accumulate fat as a way to
survive the winter,Peterson said. When the Pacific Decadal Oscillation is
in a positive phase and warmer water moves into the coast from offshore and
the south, the copepods we see are species that are smaller and dont retain
Peterson said anecdotal evidence from other researchers at OSUs Hatfield
Marine Science Center suggests that recruitment for juvenile ling cod and
other rockfish was extraordinary in 2008. Seabirds, including pelicans and
a large murre colony at Yaquina Head, were healthy and well-fed. And there
was a large population of sand lances a small baitfish that feeds on copepods.
If there is a downside, Peterson says, it is that the survey didn't find as
many juvenile coho salmon in 2008 as the scientists had hoped. The number
of juvenile chinook, on the other hand, was 2.4 times higher than any other
survey recorded in the past 13 years, Peterson said. The scientists used an
array of nets in their survey, including a trawling net as tall as a
five-story building and as wide as half a football field.
Though 2008 has been a banner year for ocean conditions and many fish
species it is too early to know what the future holds for ocean conditions
or fish runs. The Pacific Decadal Oscillation has been shifting more
rapidly between warm and cool phases, possibly in response to climate
change. A positive phase, characterized by warm, less-salty water, occurred
from 1925 to 1947, followed by a negative phase of cooler, saltier water
from 1948 to 1976. Then another positive phase took over and lasted through
the powerful El Nino of 1998.
Since then, however, the regimes have been much shorter. The PDO was
negative from 1999 to 2002, positive from 2003 to 2006, then abruptly
shifted to cooler waters during the last two years. Will this latest
cold-water regime last two years or two decades?
"That's the million dollar question",Peterson said.
Peterson and his colleagues have received a grant from NASA to track the
source of the cold water to see if it has circulated from the Gulf of
Alaska through an advection process, or is the result of a different
upwelling pattern, bringing deep water to the surface. However, sea surface
temperatures havent dropped as much as temperatures lower in the water column.
Temperatures recorded this year at a sampling station five miles west of
Newport, at a depth of 50 meters, were the coldest in the 13 years theyve
been measured. This suggests to Peterson that the ocean is becoming more
stratified, which is consistent with climate change models. Those same
models also suggest more annual variability in ocean conditions.
The year 2005 was one of the worst in history, as delayed upwelling caused
a food shortage that led, among other things, to the collapse of the
Sacramento River chinook salmon run,Peterson said. In contrast, 2008 has
been one of the best years on record and though its a generality, cold
water usually means good things for salmon.
We just dont know how long this is going to last.
from IFR and PCFFA news...
14:27/02. SCIENTISTS REPORT GOOD OCEAN CONDITIONS ON THE WEST COAST: In
what may be the best news this year for the West Coast salmon fleet,
scientists at the Hatfield Marine Science Center in Newport, Oregon are
reporting that the ocean is more productive now than it has been in
decades. Ocean conditions have improved, according to the scientists,
because of a huge influx of cold water which may be the result of the
Pacific Decadal Oscillation (PDO). The PDO is a climate pattern that shifts
between warm and cool cycles every 20 to 30 years. According to Bill
Peterson, a fisheries biologist with the National Marine Fisheries Service
who participated in the study, the PDO is the coldest it has been since
1955. The cold water influx, a result of sustained upwelling, has led to a
large growth of phytoplankton and drawn a large biomass of copepods south
from the Gulf of Alaska.
For salmon fisheries this is good news. There is a lot of forage
species in the ocean and scientists are also reporting large numbers of
juvenile chinook salmon. Scientists conducting nearshore trawl surveys from
Newport, Oregon to LaPush, Washington of juvenile chinook salmon reported
higher numbers than anytime in the past 11 years. There are 2.4 times as
many juvenile chinook salmon as there have been in the past 11 years;
however, the numbers of coho salmon, which depend more on inland habitat
than chinook, are still depressed.
The composition of the different chinook stocks from the trawl
surveys is not known. The majority of the salmon caught in the Oregon and
California salmon fisheries originate from the Sacramento River, a river
system that has produced very few juvenile salmon in the past two years.
The Columbia River system has seen large numbers of salmon return this year
and the Snake River, a tributary of the Columbia, has seen near record
levels of sockeye and chinook return. Scientists speculate that increased
flows over and around dams may have contributed to the higher numbers of
salmon returns to those rivers. The Klamath River too has seen some
improvement to salmon returns this year, as compared to 2006 disaster
levels. The key question for salmon fisheries in the next few years is
whether enough juvenile salmon made it out of the San Francisco Bay-delta
in order to take advantage of some of the best ocean conditions in decades.
The effect that the current cold phase of the PDO will have on
salmon fisheries depends on how long its lasts. Unfortunately, no one knows
how long it will last. Scientists speculate that the PDO cycles have been
shortening in length in the past 50 years, possibly as the result of
climate change. The question of how long this cold phase will last remains,
as Bill Peterson the fisheries biologist says, the million dollar question.
For an 18 December press release from Oregon State University go to
For a 19 December article in the Oregonian go to
A WEEKLY QUOTA OF FISHERY SHORTS CAUGHT AND LANDED BY THE INSTITUTE FOR
FISHERIES RESOURCES AND THE PACIFIC COAST FEDERATION OF FISHERMEN'S
~WE HOOK THE NEWS THAT'S FIT TO NET~
Vol. 14, No. 27
26 December 2008
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