Big benefits for whales from their big appetites
World’s biggest cetaceans eat more than previously thought, highlighting their role in maintaining productive oceans.
Pioneering research has shown that baleen whales, the largest animals in the world, eat three times more prey than previous estimates have suggested. This has led scientists to believe that these animals and their monster-sized appetites play a bigger role in sustaining healthy marine environments than was once thought.
Researchers from Stanford University in California attached high-tech tags to over 300 baleen whales from seven species including blue, fin and humpback whales allowing them to record the whales’ movements and document details of their feeding patterns.
Through a combination of aerial photography and acoustically measuring the density of key prey species, most notably krill, the scientists were able to establish the average amount of food eaten daily by the whales.
This revealed that whales in the Southern Ocean eat about twice as much krill as previous estimates suggested and that krill-feeding blue and humpback whales off the coast of California eat two to three times more than previously thought.
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Humpback whale. ©Matt Maran/Nature Picture Library.
“There are implications for how we manage ecosystems, for example the amount of krill we extract from the Southern Ocean is based on calculations of how much the predators in that ecosystem require,” says Matthew Savoca from Stanford University.
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“Whales recycling nutrients in their faeces appears to have been key to the high productivity found in the Southern Ocean prior to the 20th century.”
Through eating krill and then defecating, whales release iron locked within the krill back into the ocean. This is then made available to phytoplankton, which forms the base of the oceanic ecosystem and upon which the krill and other small invertebrates then feed themselves.
Main image: Baleen whales such as these bubble-net feeding humpbacks in Alaska have bristle-like baleen plates in their mouths made of keratin through which they sieve their prey. © Paul Souders/Getty