This is the first study of its kind and is carried out by an international team of scientists that includes researchers from the University of British Columbia. Their findings will appear in the October 28 issue of the open access journal PLoS Biology, published by the Public Library of Science.
The team compared the survival rates of out-migrating, juvenile spring Chinook and steelhead salmon from two river basins: the heavily dammed Snake and Columbia Rivers and the free-flowing Thompson and Fraser Rivers – both critical spawning grounds for numerous salmon species.
Using technology that has only recently been available, the team electronically tagged juvenile salmon (smolts) and monitored their journey from freshwater into the ocean via a large-scale acoustic telemetry system called the Pacific Ocean Shelf Tracking (POST) array.
"It came as quite a surprise to us that the Fraser River salmon populations studied have lower survival than the Columbia River study populations," says Erin Rechisky, one of the study authors and a PhD Candidate in the UBC Dept. of Zoology.
Rechisky stresses that there is not yet sufficient evidence to reach any conclusions. "Clearly dams are not good for salmon. What is unclear is whether the Fraser River has a problem that cuts salmon survival to that of a heavily dammed river, or whether factors other than dams play a larger, unsuspected role in salmon survival."
Only in recent years have acoustic tags become small enough for scientists to implant them into juvenile salmon and track them as they migrate downstream. These innovations enabled the team to gather data on salmon smolts in the Fraser River. Before that, it was only possible to measure juvenile survival where salmon gathered in dam bypasses like those in the Columbia and Snake Rivers.
The lower Columbia and lower Snake Rivers currently have eight major hydroelectric dams combined. During the late 1930s when the first dams began to go up, salmon survival rates began to plummet, hitting mortality highs during the 1960s and 1970s due to a combination of warmer waters, fish-grinding turbines and new predators. Since then, the U.S. government has invested in major restoration measures to improve salmon survival rates.
Current conservation efforts have focused on helping smolts pass through the hydropower system. However, the scientific team aims to clarify with future studies using POST technology whether dam passage in itself has long-term detrimental effects that impact salmon's ocean survival.
The researchers note that threats beyond the rivers are taking a heavy toll on salmon. These include habitat destruction, competition with hatchery fish, harvesting and large-scale changes in ocean climate.
Lorraine Chan | EurekAlert!
100 % Organic Farming in Bhutan – a Realistic Target?
15.06.2018 | Humboldt-Universität zu Berlin
What the size distribution of organisms tells us about the energetic efficiency of a lake
05.06.2018 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
19.06.2018 | Physics and Astronomy
19.06.2018 | Life Sciences
19.06.2018 | Physics and Astronomy