Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hatchery salmon may endanger wild cousins

22.11.2002


Wild salmon in the Pacific Northwest are in trouble -- 26 populations are listed as threatened or endangered -- and many conservationists fear hatcheries are a big part of the problem. In support of this belief, new research suggests that hatchery-reared steelhead are a threat to wild chinook in the Snake River.



"Our work suggests that steelhead released from hatcheries may increase the extinction risk of wild populations of Snake River chinook," say Phillip Levin and John Williams of the National Marine Fisheries Service in Seattle, Washington, in the December issue of Conservation Biology.

West Coast hatcheries have produced salmon for more than a century and today release more than a billion each year. Most of the salmon in the Columbia River Basin are hatchery-reared, including more than 70% of both steelhead and spring-run chinook adults.


Despite these enormous hatchery releases, wild steelhead have dropped 75% in the last 30 years and wild spring-run chinook have dropped more than 95% in the last 40 years. While some people think hatcheries are contributing to these declines, little is known about how hatchery-reared fish affect wild populations.

Levin and Williams used existing population estimates to see if there is a link between hatchery steelhead and the survival of wild salmon (steelhead and chinook) in the Snake River, which is the Columbia’s largest tributary. The researchers measured survival by comparing how many juveniles migrated toward the sea (smolts) with how many adults returned over the course of 20 years (1977-1997). The number of hatchery steelhead released ranged from about 4 to 10 million per year.

The results suggest that hatchery steelhead do not affect wild steelhead, but that they may threaten wild chinook. "We observed a strong negative association between releases of hatchery steelhead and smolt-to-adult survival of wild chinook salmon," say Levin and Williams. Specifically, when hatchery releases doubled, the smolt-to-adult survival of wild chinook dropped about 90%.

Hatchery steelhead smolts are roughly 10 times bigger than wild chinook smolts, and the researchers think that this could increase the chinook’s stress when the two types of salmon are packed together in barges; the barge trip from the Snake River’s Lower Granite Dam to the Columbia River estuary takes several days. Moreover, hatchery steelhead are aggressive fish that could easily outcompete the more timid wild chinook for food. Indeed, when they reach the estuary, hatchery steelhead often have full stomachs but the chinook do not.

As salmon continue to decline in the Pacific Northwest, some hatcheries are shifting their goals from producing bulk quantities for commercial fisheries and sport fishermen to replenishing wild populations. "Conventional steelhead hatcheries clearly do not lower extinction risks or promote biodiversity," say Levin and Williams. "But the question of whether hatcheries can be altered to aid rather than hinder recovery remains unanswered."


CONTACT:

Phillip Levin (206-860-3473, phil.levin@noaa.gov ) John Williams (206-860-3277, John.G.Williams@noaa.gov)

FOR MORE INFORMATION:

Northwest Fisheries Science Center research issue papers: http://www.nwfsc.noaa.gov/issues/
hatchery fish and ESA listings: http://www.nwr.noaa.gov/HatcheryListingPolicy/AlseaResponse.html
Columbia River Basin hatcheries: http://www.nwr.noaa.gov/occd/110901_4.pdf
For PDFs of papers, contact Robin Meadows: robin@nasw.org; http://nasw.org/users/rmeadows

For any photos provided by researchers:
To register for media access to the TOC and our expert directory: http://www.conbio.org/scb/information/media/
For more information about the Society for Conservation Biology: http://conservationbiology.org/

FAQ: SCB is developing a conservation biology FAQ; please help us make it useful to you by sending suggestions for questions to Robin Meadows: robin@nasw.org

Phillip Levin | EurekAlert!
Further information:
http://www.nwfsc.noaa.gov/issues/
http://www.nwr.noaa.gov/HatcheryListingPolicy/AlseaResponse.html
http://conservationbiology.org/

More articles from Ecology, The Environment and Conservation:

nachricht Rain is important for how carbon dioxide affects grasslands
06.03.2019 | University of Gothenburg

nachricht Northeast-Atlantic fish stocks: Recovery driven by improved management
04.02.2019 | Johann Heinrich von Thünen-Institut, Bundesforschungsinstitut für Ländliche Räume, Wald und Fischerei

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

Im Focus: Revealing the secret of the vacuum for the first time

New research group at the University of Jena combines theory and experiment to demonstrate for the first time certain physical processes in a quantum vacuum

For most people, a vacuum is an empty space. Quantum physics, on the other hand, assumes that even in this lowest-energy state, particles and antiparticles...

Im Focus: Sussex scientists one step closer to a clock that could replace GPS and Galileo

Physicists in the EPic Lab at University of Sussex make crucial development in global race to develop a portable atomic clock

Scientists in the Emergent Photonics Lab (EPic Lab) at the University of Sussex have made a breakthrough to a crucial element of an atomic clock - devices...

Im Focus: Sensing shakes

A new way to sense earthquakes could help improve early warning systems

Every year earthquakes worldwide claim hundreds or even thousands of lives. Forewarning allows people to head for safety and a matter of seconds could spell...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Levitating objects with light

19.03.2019 | Physics and Astronomy

New technique for in-cell distance determination

19.03.2019 | Life Sciences

Stellar cartography

19.03.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>