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
Reducing household waste with less energy
18.01.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH
Joint research project on wastewater for reuse examines pond system in Namibia
19.12.2016 | Technische Universität Darmstadt
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
18.01.2017 | Power and Electrical Engineering
18.01.2017 | Materials Sciences
18.01.2017 | Life Sciences