Researchers tag 8 pilot whales in Hawai’i then observe them into the darkness. What they discover is “unbelievable”

The inhabitants of short-finned pilot whales within the water round Hawai’i have to eat hundreds of thousands of squid every year to maintain up their deep-diving way of life, in keeping with a brand new examine.

To learn the way a lot these dolphins have to eat, the staff tagged eight people with particular trackers that measured motion, depth and sound in addition to watching the whales hunt via underwater cameras. 

They then measured the scale of the whales utilizing drone footage and mixed the info to estimate how a lot vitality the animals have been utilizing as they swam via the ocean and down into the deep-sea. This is the primary time researchers have calculated an “energetic budget” for this inhabitants. Their findings are revealed within the Journal of Experimental Biology.

“This innovative approach gave researchers an unprecedented glimpse into the pilot whales’s watery world,” says Hawaiʻi Institute of Marine Biology (HIMB) in a press release. 

The short-finned pilot whales that decision Hawaiʻi residence are genetically distinct from different populations, they usually don’t migrate. The pilot whales (that are, technically, a species of dolphin) spend all yr with their pod, trying to find squid within the deep waters across the islands. 

“Pilot whales are one of the only oceanic dolphins that regularly dive to extreme depths – up to 1,000 metres – to find prey,” says lead creator William Gough, postdoctoral researcher at HIMB’s Marine Mammal Research Program (MMRP). “This deep-diving, high-risk foraging strategy requires a delicate balance between the energy they spend and the energy they acquire. Our study is the first step in quantifying that balance for this specific population.”

Using the tagging knowledge, the researchers may determine how a lot vitality the animals wanted for swimming and diving. Comparing this with the vitality gained from their prey, they decided that, on common, one grownup would wish to eat between 82.2 and 201.8 squid every day to get sufficient vitality to go about their every day enterprise.

There are round 8,000 pilot whales within the Hawaiian inhabitants, which means they would wish to eat between 241 and 591 million squid every year. 

The researchers additionally shared footage of pilot whales zooming via deep, darkish waters – the place the strain is 800 instances greater than on the floor – on the lookout for squid. Watching them “capturing their food in complete darkness, feels unbelievable to me,” says Gough. “It’s truly a privilege to document the lives of these elusive, deep-diving whales.”

Understanding how a lot animals have to eat to outlive is a crucial a part of defending them as a result of this knowledge helps consultants monitor for adjustments within the ocean which may hurt the inhabitants.

“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,” says Gough.

“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.”

Top picture: short-finned pilot whales in Hawai’i. Credit: HIMB Marine Mammal Research Program

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