[env-trinity] Klamath Salmon
bwl3 at comcast.net
Wed Jul 12 10:58:47 PDT 2006
Klamath turning out few young salmon; Biologists note small chinook numbers;
many fish are sick
Eureka Times-Standard - 7/12/06
By John Driscoll, staff writer
Biologists are seeing few young Chinook salmon on the Klamath River and its
tributaries this year, and already some of them are falling sick, possibly
with diseases that have killed hundreds of thousands of fish in recent
Agencies are still waiting to hear from a laboratory exactly what's making
an increasing number of fish ill.
Scientists are still trying to understand the dynamics of how the Klamath
fish are getting sick and what can be done about it. With a marginal run of
adult Chinook this fall, fewer young salmon were apparently produced. But
heavy rains in late December and January may have also wiped out many of the
salmon redds, nests where salmon eggs rest until they hatch.
"We're just not seeing a lot of fish," said Randy Brown, deputy field
supervisor for the U.S. Fish and Wildlife Service's Arcata Field Office.
Chinook are the mainstay of the Klamath's tribal and sport river fisheries,
and for ocean commercial and recreational fisheries. This fall, so few adult
fish are expected to return to the river that commercial fisheries were
canceled up and down the coast, while tribal and sport fisheries were
Federal legislators and California's and Oregon's governors have been
pressing for government aid to buoy the latent fishing fleet and other
The California Department of Fish and Game watches fish on both the Scott
and the Shasta rivers, main tributaries of the Klamath.
Fish and Game biologist Bill Chesney said the number of adults that returned
last year wouldn't explain the low numbers of chinook being seen this year.
He suspects the big winter rains roiled redds.
"They never had a chance to incubate and get out of the gravel," Chesney
In the tributaries, at least, there have been no obvious disease outbreaks.
And one piece of good news is that there are more coho salmon -- the
Chinook's threatened cousin -- than in recent years.
Low juvenile numbers don't necessarily equate to poor runs three and four
years out, Chesney said.
If the little salmon can get to the ocean, there are currently favorable
conditions, with plenty of food generated by upwelling caused by strong
northwest winds. That often means that a higher percentage of the young
salmon that migrate down the Klamath to the sea survive to return later.
But the lower Klamath River has in recent years been hard on salmon.
Outbreaks of parasites have stricken young fish, which are more susceptible
to disease when they are stressed by high water temperatures or poor water
quality, both common during the summer.
This year, since the winter was so wet, there are higher flows in the main
river than in recent years. Some believed that big flows would cut the
number of tiny worms that are an intermediate host for the parasites,
potentially reducing the number of "hot spots" in the river where fish are
Oregon State University researcher Jerri Bartholomew said it does appear
that the worms are not in all the places they have been in recent years.
The presence of the worms is not related to the presence of disease in fish.
There are some areas where there are lots of uninfected worms, and so play
no role in infecting fish. In the lower river, there appear to be fewer --
but heavily infected -- worms. The longer young fish are exposed to parasite
spores the more likely they are to become infected. Also, the higher the
water temperature, the more abundant the parasites, scientists believe.
But if the winter rains helped, they did not eliminate the problem.
"It may not be a single-year cure," Bartholomew said. "It may not be a cure
Chair, Friends of Trinity River
Advisor, California Trout, Inc
PO Box 2327
Mill Valley, CA 94942-2327
415 383 4810 ph
415 383 9562 fx
bwl3 at comcast.net
bleydecker at stanfordalumni.org
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