[env-trinity] 2008 Ocean Conditions for Fish Among Best in Half-Century

Sari Sommarstrom sari at sisqtel.net
Fri Jan 2 11:27:34 PST 2009


Media Release


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 
Science Center.

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...

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 

Vol. 14, No. 27
26 December 2008
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www2.dcn.org/pipermail/env-trinity/attachments/20090102/2eb21e4c/attachment.html

More information about the env-trinity mailing list