Millions of capelin fall victim to unprecedented cod feast
Scientists have observed the largest single instance of capelin predation ever recorded, according to IFL Science. Over the course of four hours, millions of codfish attacked the capelin school. During this brief period, 10 million fish perished.
11:54 AM EDT, November 1, 2024
Capelin, or Mallotus villosus, are small fish that inhabit the waters of the northern Atlantic and feed on plankton and krill. IFL Science explains they are a crucial part of the food chain, playing a role in northern oceans similar to anchovies in warmer waters.
Threat from predators
Mallotus villosus are vulnerable to predators while searching for spawning grounds. The greatest threat comes from codfish, which prey on capelin during their migration to their own spawning grounds.
An article published in the journal Communications Biology notes that MIT scientists, using Ocean Acoustic Waveguide Remote Sensing sonar, detected a gigantic school of capelin extending for dozens of miles. Nicholas Makris from MIT estimates the school could have consisted of 23 million fish, weighing about 912,000 pounds.
Capelin did not previously form schools
Capelin gathered in such a large group to adopt a unified speed and direction. While schooling behavior is observed in many fish species, it had not been seen in capelin before, according to IFL Science. However, this large concentration makes the capelin school an easy target for predators. Scientists calculated that during the observation with the sonar, approximately 10.5 million capelin were killed.
"This is happening over a monstrous scale, and we’re watching a wave of capelin zoom in, like a wave around a sports stadium, and they kind of gather together to form a defense," said Makris. He noted that predators behave similarly. "[They are] coming together to coherently attack," he added.
While the scale of this event is vast, it does not threaten the overall capelin population. However, rising global temperatures might make some capelin spawning grounds unsuitable, forcing them to concentrate in fewer locations. This could increase the risk of predator attacks.
