Baleen whales eat three times more krill than we thought

Baleen whales are the largest animals connected Earth, and they are adjacent hungrier than we had assumed, which has immense implications for marine ecosystems

Life 3 November 2021

By Chen Ly

A humpback whale feeds disconnected the seashore of California

John Durban

Baleen whales, the largest animals successful the world, devour 3 times much prey than erstwhile estimates suggested. The find implies that these whales play a larger relation successful sustaining marine ecosystems than we had thought.

Matthew Savoca astatine Stanford University successful California and his colleagues tracked 321 tagged baleen whales from 7 species, including the bluish whale (Balaenoptera musculus), the fin whale (Balaenoptera physalus) and the humpback whale (Megaptera novaeangliae). The researchers followed these whales passim the Atlantic, Pacific and Southern Oceans and estimated their feeding patterns utilizing aerial photographs of the whales’ foraging areas and acoustic measurements of prey density, chiefly crustaceans specified arsenic Antarctic krill (Euphausia superba).

The squad recovered that the mean magnitude of prey consumed per time by the 7 baleen taxon was betwixt 5 and 30 per cent of their assemblage wide – a scope that is 3 times higher than erstwhile mean estimates.

In the Southern Ocean, the squad estimated baleen whales ate astir 430 cardinal tonnes of krill per twelvemonth earlier concern whaling began successful the aboriginal 20^th century. This is doubly the estimated wide of krill successful our oceans today.

“This caller higher estimation is important for the functioning of water ecosystems due to the fact that whales enactment arsenic elephantine nutrient recycling plants,” says Savoca, “By consuming adjacent much prey than antecedently thought successful astir cases, they are besides pooping more, and that poop is really marine fertiliser.”

This fertiliser sparks the maturation of marine plants, including phytoplankton, and provides nutrient for krill and different tiny fish.

Emma Cavan astatine Imperial College London, who wasn’t progressive successful the study, says: “It is counter-intuitive to deliberation that if determination are much krill predators, determination volition beryllium much krill. But it highlights conscionable however analyzable biology is, arsenic really the beingness of whales whitethorn person fertilised the Southern Ocean with nutrients, thereby stimulating phytoplankton growth, which is the nutrient the krill eat. It truly is simply a existent ellipse of life, and we are lone conscionable opening to recognize it.”

The survey highlights the important relation that recovering whale populations play successful restoring marine ecosystem functions.

“There’s a assortment of passive and progressive things to promote whale recovery, specified arsenic much regulations and marine protected areas successful our oceans,” says Savoca.

Journal reference: Nature, DOI: 10.1038/s41586-021-03991-5

Sign up to Wild Wild Life, a escaped monthly newsletter celebrating the diverseness and subject of animals, plants and Earth’s different weird and fantastic inhabitants

More connected these topics:

• marine biology
• whales