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 Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society

nachricht Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>