Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Transporting Juvenile Salmon Hinders Adult Migration

09.12.2008
Scientists have discovered that management efforts intended to assist migrations of salmon and steelhead trout can have unintended consequences for fish populations. Juveniles that are transported downstream on boats can lose the ability to migrate back to their breeding grounds, reducing their survivorship and altering adaptations in the wild.

Transportation programs have been in place for over three decades to improve the survival of fish that hatch in rivers but migrate downstream to the ocean, where they live most of their adult lives. Adults then swim back up the river to mate, lay eggs and finally die in the same area where they were born. These fish can travel hundreds of miles and make dramatic ascensions up waterfalls and past dams.

When dams block rivers, however, the migrating fish – especially juveniles – can have a tough time traveling between their spawning grounds and the open ocean.

“Juveniles trying to get back to sea usually go over the spillways or past the dam’s turbines,” says Matthew Keefer, a biologist at the University of Idaho and the lead author on the study, which appears in the November issue of Ecological Applications.

Going past a dam’s turbines, however, can kill many young fish. In response, management efforts help salmon and steelhead trout avoid dams altogether by transporting juveniles past dams toward the ocean on river-faring barges.

But Keefer has found that this free ferry ride can create problems when the juveniles grow up. He and his colleagues Christopher Caudill, Christopher Peery and Steven Lee at the University of Idaho tracked the movement patterns of adult salmon and steelhead trout along the Columbia and Snake rivers in Washington and Oregon. They found that, when compared to fish that migrated naturally, transported juveniles had lower survivorship as adults and were less likely to find their way home.

“Adult fish usually move steadily upstream toward their spawning grounds, but some will instead move back downstream over dams,” says Keefer. This phenomenon, called fallback by fisheries managers, occurs more often in adults that were barged out as juveniles than in those that migrated naturally.

“It’s not clear if they’re just running out of steam swimming up the river or if they get disoriented and move back downstream in search of cues from their home river,” Keefer says.

The scientists believe that being carried on a barge prevents young fish from learning about important environmental signals during a formative time of their juvenile lives. A barge can take them the same distance in two to three days that would normally take them several weeks, Keefer explains. Traveling great distances by boat – in this study, at least 215 miles – appears to garble the natural cues these fish use to find their way home.

Keefer’s results also suggest that transported fish are more likely to stray from their home tributary. If these lost fish – often from hatchery populations – breed with another wild population, the resulting gene flow can reduce that population’s evolutionary fitness.

“Salmon have a life history that represents a long legacy of adaptation to local conditions,” Keefer says. “The fish are well-adapted to specific rivers, and when you dilute their unique genetic makeup, it can reduce the productivity of the overall population.”

A satisfactory solution is difficult to find, Keefer says. Managers could barge fewer juveniles, but then more fish would die while trying to pass the dams. They could also release more water over dam spillways to help juveniles pass downstream, but that would reduce the amount of energy the dams produce. A third option is to slow down the barges so the trip resembles the time it takes juveniles to swim to the ocean. But boats are a stressful environment for fish, and the close quarters within the ships increase the risk of disease.

“It’s tough to find a solution that could handle all the challenges in this system,” Keefer says. Scientists and salmon managers hope to find the ideal solution: one that would preserve native fish populations and maximize their survival while keeping the integrity of energy-producing dams.

To access images associated with this article, please contact Christine Buckley at christine@esa.org or at (202) 833-8773 ext. 211.

The Ecological Society of America is the world’s largest professional organization of ecologists, representing 10,000 scientists in the United States and around the globe. Since its founding in 1915, ESA has promoted the responsible application of ecological principles to the solution of environmental problems through ESA reports, journals, research, and expert testimony to Congress. ESA publishes four journals and convenes an annual scientific conference.

Christine Buckley | Newswise Science News
Further information:
http://www.esa.org

More articles from Ecology, The Environment and Conservation:

nachricht Waste in the water – New purification techniques for healthier aquatic ecosystems
24.07.2018 | Eberhard Karls Universität Tübingen

nachricht Plenty of habitat for bears in Europe
24.07.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

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: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

'Building up' stretchable electronics to be as multipurpose as your smartphone

14.08.2018 | Information Technology

During HIV infection, antibody can block B cells from fighting pathogens

14.08.2018 | Life Sciences

First study on physical properties of giant cancer cells may inform new treatments

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>