Honolulu, Hawai‘i – Researchers have determined how much squid short-finned pilot whales must consume to survive in Hawaiian waters, solving a long-standing mystery about their daily diet. The study reveals that these deep-diving whales eat between 82 and 202 squid per day, totaling as many as 88,000 tonnes of squid per year across the population.

Scientists from the USA, Spain, Australia and Denmark published their findings in the Journal of Experimental Biology, confirming that the whales’ enormous demand is only a small fraction of the region’s abundant squid supply.

Pilot whales, which can dive to depths of up to 1700m while hunting, have remained poorly understood in Hawaiian waters.

“Short-finned pilot whales have been studied in locations around the world, but relatively little is known about them in Hawaiian waters,” said William Gough of the University of Hawai‘i at Mānoa, who led the research.

The team attached suction-cup data tags to eight whales. Each device carried motion sensors, a light-equipped camera, hydrophones to detect echolocation clicks and GPS.

“Ideally, we attached the tag right behind the blowhole facing the head, so we could see any foraging at depth,” Gough explained.

A drone flown 25m above each whale recorded video to measure body size.

When the tags were recovered — some drifting up to 50 miles in rough waters — the scientists documented 118 deep dives. Each whale averaged about 39 dives a day and reached depths of up to 864m.

By analysing tail-beat patterns, the team calculated that the whales expend 73.8 kJ/min while diving and 44.4 kJ/min at the surface. Hydrophone data revealed roughly four squid captures per dive, with each squid providing about 560 kJ of energy.

Using these numbers, they found that each whale consumes between 82 and 202 squid per day, adding up to around 73,730 squid per whale annually.

With a population estimated at up to 8,000 whales, the total consumption reaches 88,000 tonnes of squid each year — still only a small portion of the local ecosystem.

“These results show that short-finned pilot whales are in relatively good shape in Hawai‘i, having found an abundant and reliable source of food,” said Gough.

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