How did it happen?

According to researchers from the Massachusetts Institute of Technology (MIT) in the USA and the Marine Research Institute in Norway, an unusually large density of fish may attract predators, 24 Kanal reported with reference to Nature Communications Biology.

This is the first time we observe predator-prey interactions on such a large scale. It’s a constant struggle for survival,
– says Nicholas Makris, an oceanographer at the Massachusetts Institute of Technology.

Makris, along with MIT colleagues Shurav Pednekar and Akita Jain and Marine Research Institute behavioral ecologist Olav Rune Gode, observed the dynamics of this large-scale event: by tracking the echoes of sound waves coming from animals’ swim bladders.

The team used a new large-scale multispectral underwater acoustic sounding technique to monitor the characteristic frequencies of different species; this allowed researchers to track their interactions over an area of ​​tens of kilometers.

Cod has a large swim bladder that echoes like Big Ben. At the same time, capelin has small swim bladders that resonate like the highest notes on a piano.
– explains the scientist.

Capelins gather in large flocks to save energy during their migration from the Arctic to Europe every February. Grouping ensures that they do not get carried away by the currents and act collectively. If they are close enough together, they can detect the average speed and direction of other fish they sense around them and then form a huge, interconnected school. But such behavior is associated with a certain risk.

Recently analyzed data recorded up to 23 million capelin individuals lost in herds. In response, 2.5 million predatory Atlantic cod staged their own “wild hunt” in preparation for the holiday.

Fortunately, anchovy-sized capelin generally number billions of individuals throughout the ocean, so the event the team recorded may have wiped out at most 0.2 percent of the population. But as large, shallow-water fish species decline, understanding the dynamics of predator-prey relationships becomes increasingly important.

Who needs it and why?

Shocking 97 percent of migratory fish species are in danger of extinctionIncluding valuable species such as Atlantic salmon. Sound imaging used by scientists could help researchers detect endangered fish species.

Catastrophic predation-related natural events can shift the balance between local predators and prey in a matter of hours. This is not a problem for a healthy population with many spatially dispersed habitats. But as the number of such habitats decreases due to climatic and anthropogenic stresses, the natural “disaster” cases that scientists are witnessing this time could lead to dramatic consequences for both this species and many other species that depend on it. food chains.