[env-trinity] Siskiyou Daily News 5/14/10

Byron Leydecker bwl3 at comcast.net
Tue May 18 13:30:09 PDT 2010


Discovery students learn about fish disease on the Klamath

Siskiyou Daily News-5/14/10

By Jamie Gentner 

 

Of all the issues affecting Chinook and Coho salmon, the key issue limiting
their numbers is fish health, according to Matt Baun of the U.S. Fish and
Wildlife Service. A  major detriment to the health of juvenile salmon on a
portion of the Klamath River just below Iron Gate Dam is Ceratomyxa Shasta
(C. Shasta) - a major disease organism infecting the juveniles.

 

"This issue is on the verge of being in the national spotlight," Baun told
members of the media and a class of students from a Discovery High School
ROP natural resources class during a tour to learn more about the disease.

 

The group traveled to the site where researchers trap juveniles in both
screw traps and frame nets to collect data to determine the prevalence of
the C. Shasta.

 

He explained that various agencies have joined forces to form a fisheries
program that addresses the disease and other factors affecting the fish in
the third most important river for the salmon.

 

Nick Hetrick, fisheries program leader with the USFWS, said the agencies
like the USFWS and California Department of Fish and Game, and groups like
local tribes, have come together to address the issue of interjurisdictional
territory and to combine resources so the groups could find out what needs
to be done to improve fish health.

 

A vital part of those efforts is the work of fish biologists like Steve
Gough, who works out of the USFWS Arcada office. During the tour, he
explained the life cycle of the salmon.

Adult salmon densely populate the Klamath River from Iron Gate Dam to the
Shasta River confluence. They start spawning in the fall after a 200-mile
migration and dig a spawning nest where eggs incubate for up to three
months. In early spring, the eggs hatch.

 

They slowly make their way out of the gravel and into the water of the river
and start their own migration, moving from freshwater to the ocean. After
spending a few years in the ocean, the salmon will make their way back to
the Klamath, where they start the cycle over again.

 

Unfortunately, with the appearance of the C. Shasta - which just entered
documentation in 1997 - about 45 percent of the juvenile salmon aren't
making it through that whole life cycle.

 

The C. Shasta isn't necessarily always fatal to fish, USFWS Fish Health
Biologist Scott Foott said, but in the Klamath River, the parasite is
overwhelming fish.

 

The organism is produced by a worm-like creature that infects fish with the
disease that turns into spores. The infection causes bleeding in the fish,
which leads to the fish becoming anemic. It weakens the fish, which is
eventually killed by the predator.

 

When the fish dies, the spores are released into the river by the billions,
which is ingested by other fish and invades the tissue of the fish.

 

Fish Biologist Philip Colombano and biological science technicians Ryan
Slezak and Ernest Chen removed some salmon from the traps at the site of the
tour so media personnel and the students could see what they look for. Foott
held one juvenile salmon and pointed to a bleeding eye and gray gills (they
should be pinkish in color) as a sign of the C. Shasta infection.

 

"The parasite adapts - it takes advantage of the conditions of the system,"
Foott said. "The combination of the environment, the conditions and an
abundant run of salmon creates good conditions for the parasite."

 

Because the adults come to the same site in the river to spawn, he added, a
perfect cycle is created and the parasite has become native to the Klamath
instead of spreading out elsewhere.

 

That has created some detrimental impacts, Foott said.

"It is slowing restoration efforts," he said. "The stocks in the Scott and
Shasta systems have been hit hard."

 

The occurrence of the parasite has been steady over the last four to five
years, with some heavy rains scouring the site and minimizing the impact a
little. But Foott said the USFWS personnel expect the occurrence over the
next two years to be relatively high.

 

But it's something that is hard to eradicate.

 

"Only about 10 percent of adults carry 99 percent of the spores," Foott
said, so it's not easy to find those hosts and remove the parasite from the
system.

Varying the river's flow enough to scour the area could help, but "there's
not enough water in the system on a natural basis to make that possible,"
Foott said.

 

The Fisheries Program is aiming to set up models to help determine how much
water would be needed or what other routes could be taken.

"Because we would be asking for water - an extremely important asset,
especially in this area - we have to be sure that the affect would work,"
Foot said.

He said it would likely be another two to three years before any solutions
are offered.

 

"We have to do something now. We can't wait," Foott said. "So, we're going
to study these models, ask questions ... and see what can be done to bring
the infection levels down."

 

 

Byron Leydecker, JcT

Chair, Friends of Trinity River

PO Box 2327

Mill Valley, CA 94942-2327

415 383 4810 land/fax (call first to fax)

415 519 4810 mobile

 <mailto:bwl3 at comcast.net> bwl3 at comcast.net

 <mailto:bleydecker at stanfordalumni.org> bleydecker at stanfordalumni.org
(secondary)

 <http://fotr.org/> http://www.fotr.org 

 

 

 

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