If you thought that Dwayne “The Rock” Johnson ate a lot, well he’s got nothing on a dolphin.
A new study, published in the Royal Society Open Science, has managed to calculate just how many calories the cetaceans need to consume in order to keep doing what they’re doing – and it turns out that they are eating machines. The paper shows that a 200-kilogram (440-pound) dolphin will burn between 16,500 and 33,000 calories per day.
This sounds like an extraordinary amount, but according to the researchers this is actually lower than expected.
It means that the dolphins need to eat a hefty 10 to 25 kilograms (22 to 55 pounds) of fish every single day just to keep swimming in the oceans. And if you’re wondering what the point to all these calculations are, well it could play a vital role in how we manage the environments in which the animals live and leave us better informed in how to protect them.
“We can then add this up for all dolphins and estimate how much fish/prey they need,” explained Andreas Fahlman, who led the research, to the BBC. “This may be vitally important when considering managing fisheries and making sure that the quota are not too high so that animals lack food.”
It may seem like the oceans are a vast bottomless resource and that humans would never be able to outcompete all the plethora of life within it (and indeed that's how it has long been treated), but this is misguided. Fishing vessels are now so efficient at hoovering up fish and krill that many animals – such as dolphins, penguins, whales, and seals – that also rely on these food sources are literally starving to death.
To find out exactly how much dolphins therefore need to survive, the team of researchers from the Woods Hole Oceanographic Institution set out to measure the resting metabolic rate of the creatures. Over a period of four years, the scientists caught adult and young dolphins living in Sarasota Bay in Florida and recorded their vitals.
They found that dolphins require up to 33,000 calories per day, putting The Rock’s mere 5,000 to shame. Still, this all comes nowhere close to how many calories the blue whale can chomp in a single mouthful, which one study a few years back calculated to be up to a staggering 500,000.
The amount of calories burned varies depending on a number of factors, including the temperature of the water, the energy requirement of the brain, and the activity of the animal.