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Fisheries biologist Don Chapman
explains the potential effects of
climate change on salmon and people to
a group of journalists recently near
the Snake River in Oregon. - PHIL
WRIGHT/ East Oregonian Publishing
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What happens to snowpack trickles down to
fisheries
By CATE GABLE
East Oregonian Publishing Group
The temperate coastal rain forest stands of
cedar and spruce are helped by salmon
returning their nutrients to the land.
According to Steve Theberge, Oregon State
University Extension agent and Sea Grant
faculty for Clatsop County, the most important
fisheries in terms of economic output for the
region are salmon, Dungeness crab and the more
than 54 varieties of rock fish in local
waters.
"Dungeness crab has been our best money-maker,
particularly on the southern Oregon coast. For
three years in a row, we've had record takes.
We don't really know why. Typically, you don't
have three record years in a row for any
fishery. It's generally cyclical."
Theberge attributes this success, at least
partially, to the effective management of the
crab fishery. "Dungeness crab is our most
successful fishery. The idea of not keeping
females, creating a minimum size limit for
catch, and putting escape rings on the traps,
that has all worked really well."
He also cited the health of the sturgeon below
the Bonneville Dam in the free-flowing portion
of the Columbia River. "We think this is the
most stable population of sturgeon in the
world. They basically know how many are there
and what sizes they are. At least we have
accurate data about the population." (He
warned about taking sturgeon from other areas.
According to Theberge, "There are problems
above the dams with contaminants in
sturgeon.")
But Theberge said that we don't have the same
understanding of the complex life of the
salmon, nor, therefore, as effective a fishery
management plan. Salmon need cold clear waters
to remain healthy and to find their way back
from the deep ocean to their spawning grounds.
Theberge anticipated problems with the salmon
runs as global climate change continues to
affect our waters.
Kathleen Sayce, ShoreBank Pacific scientist,
agreed. "Wet winters are good for salmon.
Warm, dry summers are also tolerable. But
overall, salmon are cold-water fish; they can
tolerate hot summers but only under certain
conditions."
Again, those conditions are changing.
One of the problems salmon and other
freshwater fish such as trout will face as
climate warming continues is the decline in
the amount of snowpack in the Pacific
Northwest. Riparian zones - fresh running
streams and rivers - depend on snowmelt in the
summer to keep water levels high and water
temperatures low.
Snowpack is like money in the bank in the
Pacific Northwest; it is a store of water that
can be used slowly over time as needed.
Less snow and less snowmelt mean that we do
not have the reserves of cold water in the hot
summers when the fish need them most.
National Wildlife Federation climate
specialist Patty Glick said scientists project
that in the coming decades climate change
could bring a substantial decline in snow
accumulation in the Pacific Northwest,
especially on the west slopes of the Cascades,
the Olympics and the coastal range.
"Our region could see an additional 50 percent
decline in average snow pack in the next 45 to
75 years, significantly reducing the primary
source of water during dry summer months,"
Glick said.
Since the late 1940s, average snow pack in the
Cascades is down 35 percent. "It takes more
precipitation just to get the same amount of
snow, and that's because of warming," said
Washington's state climatologist Phil Mote.
Precipitation, however, is not a good
substitute for snowmelt. Rain often falls too
heavily, causing soil and bank erosion and
bringing mud and silt into the waterways as it
runs off the land instead of slowly soaking in
as melting snow does. Clearcutting or loss of
trees in areas bordering riparian zones simply
aggravates this run-off problem.
Peninsula oyster grower Larry Warnberg said
run-off is contributing to salmon degradation.
"We are seeing a continued loss of habitat for
salmon spawning. And hotter temperatures may
mean more fires and more mud in the creeks."
Paula Del Giudice, director of the National
Wildlife Federation's Northwest Natural
Resource Center in Seattle, said this is so.
"Salmon in the region are struggling to
survive amidst dams, water diversions and
development along river shorelines. Global
warming will add an enormous amount of
pressure onto what's left of the region's
prime cold-water fish habitat."
In a 2002 report issued by the National
Resources Defense Council, scientists
indicated that "cold-water fish such as trout
and salmon thrive in streams with temperatures
of 50 to 65 degrees. In many areas, the fish
are already living at the upper end of their
thermal range, meaning even modest warming
could render streams uninhabitable."
As with the oysters, salmon and other species
seem to be attempting to adapt to these
changing conditions. Theberge said that the
spring salmon were very late this year and
came in larger numbers than predicted. But he
reiterates that scientists have lost their
ability to make accurate predictions on what
can be expected. This makes it extremely
difficult to manage a resource.
"As climate conditions change, fisheries will
change, but how is the big question. The
biggest thing is the need for fishery managers
and those who make their living off the
fisheries industry to be flexible. When things
change, some things will benefit and some
things won't. People making a living off the
system will need to make adjustments," said
Theberge.
Sayce said another aspect of how continued
climate change could affect salmon in their
ocean-feeding phase. "The food chain could be
disrupted. The krill and phytoplankton in the
ocean are on a steep downward curve. Herring
that feed on the krill feed the salmon. And
that chain could collapse."
Washington State University Extension
professor Kim Patten's take on what warmer
temperatures will mean points in another
direction - conflicts over water. "The
reduction of snow for just a few feet in
elevation has an exponential change in the
total volume of snowpack. Less water is the
ultimate result. Salmon, agriculture, people -
who will come out on the bottom?"
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