Until very recently, marine biology had an unwritten rule about the North Pacific: the orcas are the queens and dolphins, at best, a nuisance; and at worst, food for the orcas. However, science suggests that we were really wrongsince orcas and white dolphins have been caught collaborating with each other.
It’s not a casual interaction.. It is a coordinated hunting strategy to catch the elusive Chinook salmon, documented for the first time thanks to a technological arsenal that includes drones and subjective cameras attached to the animals themselves.
This is something that has been demonstrated in the study Led by Sarah Fortune, it focuses on northern resident killer whales, a subspecies that feeds exclusively on fish. For five years, researchers were seeing something that didn’t add up: the dolphins weren’t running away from the orcas, but rather deliberately swimming toward them.
A collaboration with meaning. And these two species, which in theory should be far apart, do not collaborate just for the sake of it, but for a common good: the food. Dolphins, faster and more agile, act as scouts, locating schools of salmon. The orcas, with their brute strength and size, are responsible for the final capture of the largest specimens, impossible for a dolphin to hunt alone.
The result? A shared feast. The orcas have been observed dividing the prey and allowing the dolphins to feed on the scraps and pieces that come off, in a kind of food “non-aggression pact.” Something that escapes everything we knew until now.
How they discovered it. Observing this from a boat is really complicated, since seeing what happens underwater is almost impossible. To achieve this, the Fortune team used CATS tags. Some devices adhere to the orcas using suction cups and are like biological black boxes.
They have the ability to record high-definition video in the deep sea, capture the acoustics around them and also have accelerometers and magnetometers to record depth and movement. A complete technological set that allowed us to obtain 258 documented events of dolphins interacting near the heads of the orcas.
A silent mode. The acoustic analysis revealed the most fascinating fact about the intelligent behavior of these cetaceans. the orcasfamous for their complex use of echolocation for huntingreduced their own clicks and whistles when dolphins were present.
The researchers’ hypothesis is clear: the orcas are outsourcing the sonar. They let the dolphins do the noisy work of finding the fish and they just listen and follow their marine “hunting dogs.” It is a brutal energy optimization. The orcas are saved the metabolic cost of searching and the dolphins gain protection and access to giant salmon that their jaws couldn’t process alone.
The salmon crisis. This alliance may not be entirely natural, but rather a forced adaptation to a situation of food scarcity. Something that has meant that two predators have to learn to tolerate each other and cooperate to survive.
Images | Vidar Nordli-Mathisen
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