[env-trinity] Scienceline November 7 2008
bwl3 at comcast.net
Fri Nov 7 14:58:09 PST 2008
Chinook Salmon's Last Meal?
A cooler ocean is feeding hungry salmon, but their ultimate survival remains
Scienceline, NYU - 11/7/08
By <http://scienceline.org/author/lynne-peeples/> Lynne Peeples, posted
November 7th, 2008.
Young Chinook <http://www.nmfs.noaa.gov/pr/species/fish/chinooksalmon.htm>
salmon entering the Pacific Ocean this year are finding cooler waters and
more plentiful meals than the sea provided their parents. Because of these
improved conditions, fisheries scientists forecast a rebound in coming years
for the West Coast's most famous fish. But some researchers and fishermen
believe the respite will be temporary, and warn that future generations of
Chinook could face even more devastating declines than their ancestors did.
"Things are definitely looking up. I'm pretty optimistic," says Bill
Peterson, an oceanographer at the National Oceanic and Atmospheric
Administration, or NOAA, whose ocean monitoring detected the changing
The good news is a welcome change from the latest Chinook headlines. Despite
restrictions, only 54,000 Chinook are expected to return to the Sacramento
River this fall, according to NOAA. Just five years ago, 775,000 came back
to the river, and historic numbers-before California's population boomed
with the Gold Rush of 1849-are thought to have been between 1.5 and 2
Three years ago, the Pacific Ocean was in particularly poor shape.
Researchers documented large numbers of dead sea birds and skinny whales,
along with fewer small fish, shrimp and squid for salmon to eat. "It was
horrid," says Peterson. "Salmon went to sea in 2005, [then] probably died
within a couple weeks of getting there, and that's why there weren't any
fish to come back last year and this year."
But a recent shift in atmospheric conditions, known as the Pacific
VuJjMzPXdlYi1zaXRlcyYzNz1pbmZv#koinfo> Decadal Oscillation, is pushing cold
water from the Gulf of Alaska south to the Pacific Coast this year, and with
it plenty of plankton-the foundation of the aquatic food chain on which
salmon rely. This food source is crucial for oceangoing Chinook that
typically spend three years at sea before returning to spawn in freshwater.
Returns are therefore expected to fully reflect the ocean's shift in another
two or three years.
Longer-term projections of the Pacific Decadal Oscillation, however, are
becoming increasingly difficult. What used to be a relatively predictable
cycle of 20- or 30-year warm and cold phases has shortened to 4-year shifts
in the past decade. Whether or not these phases are being influenced by
climate change remains uncertain. "Maybe in 20 years we'll look back and
say, yeah, this is global warming . . . all the cycles have been upset,"
says Peterson. But for now, his attention is on the pending effects of ocean
The favorable ocean currents "will buy us some time," says Glen Spain,
Northwest regional director of the Pacific Coast Federation of Fishermen's
Associations. "But we have to deal with the problems inland in the
The list of freshwater issues is daunting. Hydroelectric dams and water
diversions have dried up the Chinook's traditional migratory paths and
spawning grounds. The rivers and streams that remain run shallow and
warmer-uncomfortable conditions for salmon. Soil erosion and pollution, as
well as natural floods and droughts, further destroy viable habitat. On top
of all that, the salmon also face overfishing and an altered ecosystem that
includes non-native predators and farmed fish.#
Byron Leydecker, JCT
Chair, Friends of Trinity River
PO Box 2327
Mill Valley, CA 94942-2327
415 383 4810
415 519 4810 cell
bwl3 at comcast.net
bleydecker at stanfordalumni.org (secondary)
<mailto:bwl3 at comcast.net>
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