A study published Wednesday showed that the greed of whales is three times greater than expected, confirming the primary role on the marine ecosystems of these animals that have been decimated by hunting.
Humpback whales, blue whales – the largest living animal on our planet – and other species filter seawater through baleen to feed on krill and small prey.
The study, published Wednesday in Nature, followed 321 whales to learn their eating habits. It turns out that one blue whale eats about 16 tons of krill per day – knowing that it does not feed every day.
“It’s an animal the size of an airplane, absorbing the volume of a swimming pool in a matter of seconds,” stresses study author Matthew Savoca. “Imagine running three marathons eating as much as you can and doing it for most of the summer,” he told AFP, the whale feeding season. “He really is crazy.”
Based on daily estimates for seven species around Antarctica, the study estimates that whale populations consumed up to 430 million tons of krill per year before they were wiped out by hunting, or twice the amount of krill that exists today.
Krill is especially rich in iron. Once digested by whales and released as droppings, they provide essential nutrients to the rest of the ecosystem, especially phytoplankton.
These phytoplankton serve as food for many living organisms in the oceans, provide a significant portion of the oxygen we breathe, and store carbon.
“The nutrients that phytoplankton need are in the krill, and the gut of whales excretes iron,” says Matthew Savoca, a researcher at the American University at Stanford.
This could explain the decline in krill numbers, which did not thrive when whale numbers were decimated. About 1.5 million whales were hunted in the 20th century in the Southern Ocean. “For blue whales, it was more than 99% of their population,” says Matthew Savoca.
Restoring these populations – today threatened by climate change, collisions with ships and fishing nets and fishing still practiced by a few countries – would make it possible to re-launch a virtuous circle of the entire marine ecosystem.
“Not only will there be more krill, but there will be more fish and a healthier ecosystem,” says the researcher.
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