Utilizing a new imaging technology invented by the researchers, they were able to instantaneously image and continuously monitor entire shoals of fish containing hundreds of millions of individuals stretching for tens of kilometers off Georges Bank near Boston.
They found that once large shoals of Atlantic herring reach a critical population density, a “chain reaction” triggers the synchronized movement of millions of individual fish over a large area. The phenomenon is akin to a human “wave” moving in a sports stadium. They also observed that the fish “commute” to the shallower waters of the bank, where they spawn in the darkness, then return to deeper water and disband the following morning.
The findings, published in the latest issue of Science, confirm general theories about the behavior of large groups of animals that, until now, had not been verified in nature. Previously, these theories for diverse animal groups, ranging from flocks of birds to swarms of locusts, had only been tested with computer simulations and laboratory experiments.
“As far as we know, this is the first time we’ve quantified this behavior in nature and over such a huge ecosystem,” said Nicholas C. Makris, professor of mechanical and ocean engineering at MIT, who co-led this project with Northeastern professor Purnima Ratilal.
As part of the project, two research vessels were equipped with Ocean Acoustic Waveguide Remote Sensing (OAWRS) technology, developed by professors Makris and Ratilal. Both OAWRS and conventional sensing methods depend on acoustics to locate objects by bouncing sound waves off of them. OAWRS, however, captures images of a 100 kilometer diameter area every 75 seconds, providing far more complete coverage of fish population and behavior than conventional methods. In addition, OAWRS does so at a lower frequency than conventional methods, which allows the sound to travel much greater distances with lower intensity and still provide useful information.
"After analyzing the data carefully during the initial days at sea, I noticed what seemed to be a daily pattern of fish shoal formation,” said Ratilal, assistant professor of electrical and computer engineering at Northeastern. “When I predicted what would happen the following day, and it turned out to be right, we knew we had discovered something really important."
Makris and Ratilal see potential in using OAWRS to better monitor—and conserve—fish populations. Large oceanic fish shoals provide vital links in the ocean and human food chain, they explained, but their sheer size makes it difficult to collect information using conventional methods.
Northeastern PhD. students Mark Andrews and Zheng Gong contributed to this research. Additional collaborators include J. Michael Jech of the Northeast Fisheries Science Center, Olav Rune Godoe of the Institute of Marine Research in Norway, as well as others from MIT, Northeastern and the Southeast Fisheries Science Center. The project was sponsored by the National Oceanographic Partnership Program, the Office of Naval Research and the Alfred P. Sloan Foundation, and is a contribution to the Census of Marine Life.
Jenny Eriksen | Newswise Science News
Further reports about: > Animal > Animal Behavior Patterns > Fisheries > Marine science > OAWRS > Ocean Acoustic Waveguide Remote Sensing > Science TV > chain reaction > computer simulation > conventional methods > ecosystem > fish populations > flocks of birds > shallower waters > swarms of locusts
Scientists team up on study to save endangered African penguins
16.11.2017 | Florida Atlantic University
Climate change: Urban trees are growing faster worldwide
13.11.2017 | Technische Universität München
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
22.11.2017 | Business and Finance
22.11.2017 | Physics and Astronomy
22.11.2017 | Physics and Astronomy