NEW OCEAN INDEX TOOL FORECASTS NORTHWEST SALMON
December 15, 2006, Columbia Basin Bulletin,
Fish and Wildlife News
NOAA Fisheries scientists said this week that
ocean conditions this year are about average for
juvenile salmon entering the Pacific Ocean and
vastly improved over the poor conditions observed
in 2005, which should be good for adult salmon
returns to Pacific Northwest rivers over the next
That conclusion comes from the use of a new
predictive tool to monitor the oceanographic and
biological conditions of the Northern California
Scientists at the agency's Northwest Fisheries
Science Center in Seattle have discovered many
critical links between physical conditions in the
ocean and how the biological communities within
the coastal ecosystem respond to those conditions,
according to the agency.
"We can now use this information to better
understand what's going on in our coastal ocean,
provide better forecasts of salmon returns and
help reduce the uncertainty surrounding why salmon
return rates vary so much from year to year," said
Dr. Usha Varanasi, science and research director
at the Science Center.
Since 1997 scientists at the center have been
monitoring the coastal ocean environment off
Washington and Oregon, including the Columbia
River where it empties into the Pacific, its
interaction with the California Current, and how
it affects the abundance, growth, distribution and
survival of juvenile salmon.
The California Current, a body of cold water that
flows south from British Columbia to southern Baja
California, can drag even colder water from the
subarctic domain to the Pacific Northwest coast.
This water can be supplemented with deep,
nutrient-rich water brought to the surface along
the coast in a process called upwelling.
The Science Center's information was used to
develop an ocean index to assess ocean conditions
of the Northern California Current ecosystem, and
to predict changes in adult salmon populations
from the Columbia River basin and coho salmon from
the Oregon coast.
The ocean index uses physical and biological
measurements to forecast how juvenile salmon
respond to changes in the ocean.
Physical indicators include sea-surface
temperature, salinity, local upwelling strength
and duration influenced by large-scale atmospheric
conditions over the north and equatorial Pacific
Ocean (such as El Niño).
Biological indicators include the abundance and
diversity of copepods, the microscopic animals
that form the foundation of the salmon's food
chain; the abundance of salmon predators and the
small fish salmon prey upon; and estimates of
juvenile salmon abundance collected during trawl
This year the physical oceanographic indicators
showed moderately strong upwelling and an early
spring transition, and cooler sea-surface
"We're excited that several years of research have
yielded a tool we think will significantly improve
our ability to forecast salmon runs in the
Northwest" said John Ferguson, director of the
Science Center's fish ecology division. "Early
this year we observed a lot of upwelling, which
indicates in general that we'd expect higher
salmon returns compared to recent years."
Ferguson added, however, that scientists also
observed a period of poor upwelling and warm ocean
conditions from mid-May to mid-June, a critical
time when salmon have just entered the ocean.
While the number of juvenile chinook salmon
captured during June sampling indicated good adult
returns in the future, Ferguson said sampling in
September produced very low numbers of juvenile
coho that in turn suggest poor adult returns of
"So the ocean is sending us mixed signals this
year" he said.
A full assessment of expected returns will be
developed once all of the physical and biological
ocean indicators for this year have been
evaluated. Scientists at the Center will post the
status of the dynamic coastal marine environment
off Washington and Oregon through a continuously
updated website starting in January 2007 and in an
Regional fishery managers are looking forward to
this new scientific tool because it will provide
leading indicators that forecast adult salmon
return rates up to one year in advance for coho
and up to two years in advance for chinook, and
will help them make more informed decisions.
For more information go to the Northwest Fisheries
Science Center website a http://www.nwfsc.noaa.gov