Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fish Journeying Upstream Are Hampered By Hydropower Dams

18.01.2013
Major hydropower dams in the northeastern United States, constructed with state-of-the-art features designed to allow migratory fish to pass through them on their way to spawn upstream, have failed in that regard, raising questions that should be addressed as more dams are planned worldwide.

Those findings were reported in a study published today in the journal Conservation Letters.

A team of ecologists and economists, led by Dr. J. Jed Brown of the Masdar Institute of Science and Technology in Abu Dhabi, United Arab Emirates, reported that despite the presence of fish passage facilities that were built into the dams, the actual numbers of fish that passed through them over several decades were only tiny fractions of targeted goals.

“It may be time to admit failure of fish passage and hatchery-based restoration programs and acknowledge that ecologically and economically significant diadromous species restoration is not possible without dam removals,” Brown and his colleagues wrote.

The three large river systems studied – the Merrimack, Connecticut and Susquehanna – are historically important rivers for a suite of fishes that migrate from the sea to rivers; they are called diadromous fishes by scientists and include species such as sturgeon, salmon, shad, river herring and eel.

“Once these rivers supported tens of millions of pounds of biomass of these species and provided valuable protein to a growing nation,” said Dr. Karin Limburg, a fisheries ecologist at the SUNY College of Environmental Science and Forestry in Syracuse, N.Y.

Today these river systems contain hundreds of dams. The dams with largest impacts on the fish populations are those constructed on the main stems of the rivers for hydropower generation. There are four on the Susquehanna, including one less than nine miles from its mouth at the head of the Chesapeake Bay, more than 10 on the Connecticut and five on the Merrimack.

Using publically available data collected by various agencies since the 1960s, the research team shows that these state-of-the-art fish passage facilities have been unsuccessful. Some migratory species, such as sturgeons, do not pass through at all. But even the species that do make it through do so in numbers far less than stated targets. In recent years, for example, the number of American shad, which was once one of America’s premier food fish, that passed through the dams has hovered around 2 percent of the target in the Merrimack River and close to zero percent of target in the other two rivers.

System-wide passage efficiencies, defined as passage from the most downstream dam in a river up past the uppermost main stem dam with fish passage facilities, hover at less than 3 percent. Although some fish spawning does occur downstream of the lowest dams most of these migratory species require habitat above the farthest upstream dam.

River herring, a term used to describe both blueback herring and alewife are important migratory forage fish, which have been proposed for listing under the federal Endangered Species Act. “These dams are contributing to reduced resilience of not only shad, but all diadromous species,” said Dr. Adrian Jordaan of the University of Massachusetts Amherst.

“The result is that other factors including climate change will have a greater impact on these populations that are at fractions of their historical levels.” For example, restoration targets for river herring vary from several hundred thousand to millions of fish—however, in recent years, river herring returns on these rivers have averaged less than a thousand fish.

“The consequences of the use of these failed technologies include declines in diadromous species, but also an odd, self-perpetuation of attempts to mitigate dam impacts by continuing restoration programs despite their inability to show success,” said Dr. John Waldman of Queens College. “Not only are these losses felt locally, possibly with major ramifications to fishery and biodiversity resources, but in fact they translate into lost marine production and weakened marine food webs.”

The authors note that — ironically — at one fish passage facility with an educational center, no fish passed in a typical year.

The authors support innovative solutions to this quandary, inviting more scrutiny to finding alternatives to main stem dams. In the state of Maine, for example, a creative solution developed by a broad coalition was to purchase two main stem dams on the state’s largest river, the Penobscot, but compensate the electric company with alternative power generation in tributaries considered less critical for fish reproduction.

The researchers say the case study serves as a cautionary tale not to count on fish passage facilities to mitigate dam projects, even as many developing nations look to their undammed rivers – the Amazon and the Mekong, among others – as valuable potential sources of hydropower.

“Electricity from hydropower dams is considered mature technology that is seen as ‘green energy’ because it does not generate greenhouse gases,” said Brown, the lead author. “Although hydropower dams are criticized for obstructing the movement of fishes and other creatures, many hydropower dams have fish passage facilities of one sort or another. These passage facilities appear to create a ‘win-win’ situation that allows us to enjoy both hydroelectricity and healthy fish populations. The problem is it doesn’t seem to work.”

Joining Brown, Jordaan, Limburg and Waldman in the study were Dr. Kurt Stephenson of Virginia Tech, Dr. Edward P. Glenn of the University of Arizona, and Dr. Francis Juanes of the University of Victoria.

Claire B. Dunn | Newswise
Further information:
http://www.esf.edu

More articles from Ecology, The Environment and Conservation:

nachricht How fires are changing the tundra’s face
12.12.2017 | Gesellschaft für Ökologie e.V.

nachricht Using drones to estimate crop damage by wild boars
12.12.2017 | Gesellschaft für Ökologie e.V.

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: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

A whole-body approach to understanding chemosensory cells

13.12.2017 | Health and Medicine

Water without windows: Capturing water vapor inside an electron microscope

13.12.2017 | Physics and Astronomy

Cellular Self-Digestion Process Triggers Autoimmune Disease

13.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>