Scientists believe the ravenous appetites of baleen whales – Earth’s largest creatures – and their prodigious waste – hold clues to the very health and productivity of our oceans.
Baleens include the humpback, fin, minke and blue whale, the latter being the largest creature ever to live on Earth.
The carnivorous marine mammals catch and consume vast amounts of prey. And they recycle ocean nutrients by excreting undigested food in what have been described as “volcano-like” movements.
By attaching tags to the backs of 321 whales from seven baleen species, the researchers now reckon that – before the onset of whaling in the twentieth century – and in the Southern Ocean alone – baleens were, amazingly, consuming more than twice what the world’s entire marine fisheries catch today.
Before whaling ramped up in the 19 hundreds in the Atlantic, Pacific, and Southern Oceans, they probably ate 430 million tonnes of Antarctic krill (small crustaceans found in all the world’s oceans) each year.
That’s up to thirty percent of their entire body mass, on average, and, in some areas of the ocean at least, triple the volume previously thought. And, incredibly, it’s twice the total biomass of this entire species of krill thought to exist today.
The scientists hope, if baleen numbers could somehow recover to what they were before that twentieth century whaling, their “nutrient recycling services” could not only help boost ocean productivity but restore ecosystem functions to their previous glory.
According to the Smithsonian Institute, which was involved in the study, whales both eat and excrete immense amounts of iron. It is an important nutrient which spurs the growth of phytoplankton blooms.
If it weren’t for the whales, this valuable nutrient would sink from near the surface, where the whales live (and where the iron is needed), to the bottom where it would be lost.
The findings have just been published in the journal, Nature. Lead photo: A blue whale (Balaenoptera musculus) defecates. Photo credit-Ryan Lavery (Smithsonian).
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