Scientists discovered that large whales consume at least three times the amount of food previously believed. This discovery highlights their importance to maintaining healthy oceans.
The Nature peer-reviewed journal published the study Wednesday. It provides insight into why the destruction of marine environments caused by the wiping out of millions the largest whales on Earth.
Two scientists spoke to Insider about how restoring the whale population could make a huge difference for marine environments, and may even help replenish declining fish populations.
Krill paradox
Between 1900 and 1970, 1.5 million larges whales were killed by industrial whaling in Antarctica.
Insider was told by Nicholas Pyenson (author and curator of fossil marine mammals at the Smithsonian Institution) that the largest whale species were systematically hunted.
He stated that "99% of the blue whales alive in 1900 had died by 1960."
Scientists believed that if the whales didn't prey on fish and krill, then populations would explode. Other predators would flourish as they would fill the gap in their food chain.
However, that is not the case. The ecosystem has never recovered.
Matthew Savoca (lead author of the study, and postdoctoral scholar at Stanford’s Hopkins Marine Station) said, "In reality, there was an amazing decline [of Krill] over 50 years. It's still happening today."
Insider reported that the areas with the greatest declines in krill biomass were those where most whales have been killed.
Scientists were puzzled by the "krill paradox".
Whales produce a lot more food that was previously believed
It was difficult until recently to gauge the size of whales' diets. They cannot be kept in captivity as they feed below the surface of water.
Researchers at the University of Washington developed sensors to detect fish and krill when the whale eats them.
These sensors are attached to the whales with suction cups, as shown in the video. They were used to track 321 baleens whales of seven species in the Southern Ocean which surrounds Antarctica.
The scientists discovered that the whales consume three to four times more than previously believed.
This means that the Southern Ocean's pre-whaling population would have consumed approximately 400 million metric tonnes of krill annually, which is far more than was assumed.
This is also twice the amount of Antarctica's total krill.
(Elliott Hazen under NOAA/NMFS permit 16111)
Above: Blue whale researchers approach to attach a suction cup tag.
This means that whales produce more iron-rich poop than they do sewage, which is why there was so much environmental damage after their deaths.
Savoca stated that "we believe these whales act as key nutrient recyclingrs in the ecosystem."
The iron is redistributed by the whales to the ocean's surface as they eat and urinate. This makes iron available to phytoplankton (small algae that can't grow without it).
These are then eaten by krill which is eaten by the whales.
A large amount of iron that falls to the bottom of oceans without the presence of whales would be effectively lost from the ecosystem.
Pyenson and Savoca stated that the whales are a key player in the ecosystem and that reestablishing them in the Southern Ocean would benefit the marine environment.
"You would see more krill and more whales. Pyenson stated that penguin populations could rebound as a result of a healthier ecosystem.
He said that today's whaling "doesn’t have real impact on the world’s whale population" because it is much smaller than in the past.
Pyenson stated that whales are often killed by humans in an accident, with hundreds of thousands dying from being hit by ships or getting caught in fishing gear.
Business Insider originally published this article.
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