And you thought teenage boys ate a lot? Pilot whales in Hawai’i may give the hormone-fueled, growth-spurting food engulfers a run for their money.
Researchers have calculated that a population of short-finned pilot whales (Globicephala macrorhynchus) off the coast of Hawai’i chows down on almost 2 million pounds of squids per year. They recently reported their findings in the Journal of Experimental Biology.
Other than orcas, pilot whales are the largest dolphins. So, it’s not entirely surprising they need to eat so much to sustain their remarkable body weights of up to 6,600 pounds.
Pilot whales were already known to be extraordinary—the only members of the dolphin family that regularly dive more than 3,000 feet deep to hunt, where the pressure is more than a hundred times greater than at the surface. Diving takes lots of energy, especially given that short-finned pilot whales have been clocked sprinting up to 20 miles per hour as they close the final gap with their prey. Many pilot whale populations migrate, but Hawai’i’s short-finned pilot whales are homebodies, staying in the same region with their families for life, diving down into the deep canyons off the big islands to feed.
Read more: “Humans Are Overzealous Whale Morticians”
“If they use more energy than they can find, they face an energy crisis that weakens their health, hurts their ability to fight off disease, and ultimately limits their ability to reproduce and recover the population,” says William Gough, study author and postdoc at Hawai’i Institute of Marine Biology, in a statement.
By tagging short-finned pilot whales, Gough and his colleagues tracked the marine mammals’ movements and dive depths. Combined with body size data from aerial drones and diet information from the stomach contents of stranded whales, the tracking yielded an estimate of the daily energy budget required. An adult pilot whale needs to eat, on average, 142 squids per day just to break even on energy balance. And, for Hawaii’s population of about 8,000 short-finned pilot whales, that’s about 415 million squids per year.
You’d think that all this squid gobbling would imperil the squid species around Hawai’i, but according to the study authors, the squids are doing fine, their populations both abundant and stable. This makes sense. Most squid species reproduce rapidly, reaching sexual maturity and mating within their first year of life.
What’s not fine is the possibility that human activities will disrupt the feasting of these short-finned pilot whales. “Deep-diving species like pilot whales are especially vulnerable to human-induced disturbances, such as noises from ships or changes in ocean temperature, which can disrupt foraging or increase their energetic costs,” adds Gough. 
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Lead image: Vincent Kneefel / Ocean Image Bank
