Researchers have utilized acoustic wave technology to uncover the largest recorded predation event in terms of the number of participating individuals and the area of activity.
A recent study by the Massachusetts Institute of Technology and Norwegian marine biologists reveals the interaction between predators and prey in the ocean. This frenzied feeding event occurred off the coast of Norway, where a school of cod consumed over 10 million herring in just a few hours. The research indicates that while swimming in large groups can provide benefits such as increased hunting efficiency and predator avoidance, this behavior can also make certain fish species more vulnerable to attacks, particularly when the crowd is excessively large and dense. The findings were published in the journal Communications Biology.
The number of herring consumed exceeds 10 million. (Photo: iStock).
According to Nicholas Makris, a professor of mechanical engineering and oceanography at MIT, this is the first time they have witnessed predator-prey interactions at such a massive scale. It is a struggle for survival.
Herring is a small Arctic fish comparable in size to mackerel. Every February, billions of herring migrate from the Arctic ice pack to the coastal waters of Norway to spawn. However, this event coincides with the southward migration of Atlantic cod, a species that specializes in preying on herring. Although scientists have long understood the relationship between these two species, they had never measured predation activity on such a large scale.
Using advanced sonar imaging technology, the research team observed predator-prey interactions in the waters off Norway. Cod gathered in large numbers, overwhelming their prey and voraciously consuming over 10 million herring in a short period. This represents the largest documented predation event in terms of the number of individuals involved and the area in which it occurred.
To conduct the study, experts reviewed data collected during an expedition in 2014 to the Barents Sea, utilizing the Ocean Acoustic Waveguide Remote Sensing (OAWRS) system. OAWRS is an acoustic imaging technique that employs a vertically oriented sound source to emit sound waves into the ocean. These sound waves travel through the water, bouncing off objects such as fish and other underwater structures.
A separate vessel equipped with a sound receiver continued to gather reflected sound waves from distances of several kilometers. The scientists then analyzed the data to create real-time ocean maps. “Fish have acoustic bubbles similar to bells. Cod have large bubbles that resonate with deep tones, while herring have tiny bubbles that produce high-pitched sounds, akin to the highest notes on a piano,” Makris describes.
The research team emphasizes that this mass predation event is unlikely to have a significant impact on the overall herring population. However, it reveals the potential risks that this fish species faces due to climate change. As Arctic ice diminishes, cod will have to migrate longer distances, making them more susceptible to attacks. Continuous monitoring of cod populations and their interactions with predators is crucial for understanding and mitigating threats, ensuring the health of marine ecosystems.
