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 Urban growth causes more biodiversity loss outside of cities
10.12.2019 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Wie ganze Ökosysteme langfristig auf die Erderwärmung reagieren
10.12.2019 | Universität Wien

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: Highly charged ion paves the way towards new physics

In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.

Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...

Im Focus: Ultrafast stimulated emission microscopy of single nanocrystals in Science

The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.

Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...

Im Focus: How to induce magnetism in graphene

Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...

Im Focus: Electronic map reveals 'rules of the road' in superconductor

Band structure map exposes iron selenide's enigmatic electronic signature

Using a clever technique that causes unruly crystals of iron selenide to snap into alignment, Rice University physicists have drawn a detailed map that reveals...

Im Focus: Developing a digital twin

University of Texas and MIT researchers create virtual UAVs that can predict vehicle health, enable autonomous decision-making

In the not too distant future, we can expect to see our skies filled with unmanned aerial vehicles (UAVs) delivering packages, maybe even people, from location...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

Safer viruses for vaccine research and diagnosis

12.12.2019 | Health and Medicine

NTU Singapore scientists convert plastics into useful chemicals using su

12.12.2019 | Life Sciences

Studies show integrated strategies work best for buffelgrass control

12.12.2019 | Agricultural and Forestry Science

VideoLinks
Science & Research
Overview of more VideoLinks >>>