19 August
2002
Media Contact:
Charles Hudson, CRITFC,
(503) 731-1257
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Hatchery salmon are contributing
to natural spawning
But more data needed to
direct future artificial production, scientist says
Portland, Oregon
- Chinook salmon
reared at Priest Rapids Hatchery in southcentral Washington are contributing
to the natural productivity of the Hanford Reach spawning grounds,
a Portland fishery scientist says.
But a better understanding of that contribution is needed to evaluate
the performance of hatchery-reared fish, refine goals for returning
runs and direct artificial production, according to Dani Evenson,
an ecological interactions specialist with the Columbia River Inter-Tribal
Fish Commission (CRITFC) in Portland.
Evenson, who co-authored the study with fellow CRITFC fishery scientists
Doug Hatch and Dr. André Talbot, found that an average of nearly
30 percent of the Priest Rapids Hatchery returns spawn on the Hanford
Reach, and that hatchery-reared fish contribute up to 33 percent of
adult returns to the Hanford Reach spawning grounds in a given year,
averaging almost 9 percent over the 20 years surveyed.
"Our results show that fisheries managers should consider the potential
for hatchery-reared fish to contribute to the productivity of natural
stocks as they develop recovery goals and management practices," Evenson
said. "The fraction of the hatchery population returning to spawning
grounds must be considered when estimating natural population parameters."
The proportion of Priest Rapids Hatchery fish returning to the natural
production areas in the Hanford Reach to spawn ranged from 4.64 percent
to 60.57 percent--an average of 29.83 percent--between 1979 and 2000.
The proportion of Hanford Reach returns attributable to Priest Rapids
Hatchery ranged from 1.33 percent to 33.05 percent, with an average
of 8.63 percent.
"The Upriver Bright fall chinook population could benefit by managing
the Priest Rapids Hatchery as a supplementation program for naturally
spawning fall chinook salmon in the upper Columbia River system,"
Evenson said. "The region should strive to improve data reporting
methods and standards."
A supplementation hatchery is operated in a way that encourages salmon
it rears to return to the wild to spawn instead of at the hatchery.
One method involves building raceways filled with gravel to mimic
the natural river terrain of wild salmon.
The scientists analyzed coded-wire tags recovered from about 200,000
Upriver Bright fall chinook reared at Priest Rapids Hatchery, located
at Desert Aire, Wash., and marked annually since 1973. Brights have
a shiny skin and are among the largest naturally spawning salmon population
in the Columbia Basin. They spawn primarily in the Hanford Reach,
but historically they spawned upstream of Celilo Falls, which was
destroyed following construction of The Dalles Dam in 1957.
To estimate the proportion of naturally produced smolts that were
hatchery offspring, researchers evaluated the population structure
of returning runs, escapement estimates, number of hatchery smolts
released, number of hatchery smolts marked with coded-wire tags, returning
hatchery fish, and coded-wire tag recoveries.
Priest Rapids Hatchery was built and is funded by the Grant County
Public Utility District as a mitigation facility for the Wanapum and
Priest Rapids dams. It's been in continuous operation since September
1963 and has an annual production goal of 5 million fall chinook.
In addition, 1.7 million fall chinook are reared as part of the John
Day Dam mitigation for the U.S. Fish & Wildlife Service. The hatchery's
operation involves collecting and spawning adult fish, and rearing
eggs through release as smolts. Collection and spawning take place
from September to November, and release typically occurs in mid-June,
according to the Washington Department of Fish and Wildlife.
The Priest Rapids Hatchery has been very successful," said Hatch,
one of the study's co-authors. "We are not questioning that success.
Our research simply offers suggestions on how to make further improvements
at the facility."
The Hanford Reach is the only free-flowing, non-tidal stretch of the
Columbia River in the United States, meandering 51 miles from the
foot of the Priest Rapids Dam to the slack waters of McNary Dam just
south of Richland, Wash. It provides the last significant fall chinook
spawning habitat in the mainstem river, supports numerous species
of birds, mammals, reptiles and amphibians, and shelters Indian cultural
resources and important archaeological sites.
Evenson's findings, presented at last month's International Congress
on the Biology of Fish at the University of British Columbia, Vancouver,
appears to validate concerns expressed by some fishery managers who
argue that hatchery fish should be included in Endangered Species
Act listings for Pacific salmon and steelhead.
The National Marine Fisheries Service is in the process of drafting
a new policy for how it considers hatchery fish when making Endangered
Species Act decisions in the region. The policy is part of the service's
response to a U.S. District Court ruling, which said the agency made
an improper distinction under the Act in how it treated artificially
propagated Ð hatchery Ð fish in its listing determinations.
The agency is now sharing a "working draft" of the policy with key
partners, including tribal and state natural resource agencies in
the region, the U.S. Fish & Wildlife Service, and the U.S. Department
of Justice.
"CRITFC's research continues to lend credence to our belief that hatchery
salmon are integral to natural spawning grounds not only in the Hanford
Reach, but throughout the Columbia River Basin," said Sam Jim Sr.,
chairman of the Yakama Nation's Fish & Wildlife Committee. "This further
proves that hatchery supplementation must be an essential tool for
rebuilding natural spawning populations to meet the goals of the Endangered
Species Act and tribal treaty rights."
Click here to view the entire report.
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About CRITFC
The Portland-based Columbia River Inter-Tribal Fish Commission is
the technical support and coordinating agency for fishery management
policies of the Columbia River Basin's four treaty tribes: the Confederated
Tribes of the Umatilla Indian Reservation, the Confederated Tribes
of the Warm Springs Reservation of Oregon, the Confederated Tribes
and Bands of the Yakama Nation and the Nez Perce Tribe.
CRITFC, formed in 1977, employs biologists, other scientists, public
information specialists, policy analysts and administrators who work
in fisheries research and analyses, advocacy, planning and coordination,
harvest control and law enforcement. |
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