Feeding at the ocean’s surface appears to play an important role in New Zealand blue whales’ foraging strategy, allowing them to optimise their energy use, Oregon State University researchers suggest in a new study.
Blue whales are the largest mammals on Earth. Because of their enormous size, the whales must carefully balance the energy gained through their food intake with the energetic costs of feeding, such as diving, holding their breath or opening their mouths, which slows their movement in the water. Adding to the challenge: their prey are tiny krill and they must find and eat large volumes of them to make any energetic headway.
“People think about whales having to dive deep to get to the densest prey patches, but if they can find their prey in shallow waters, it’s actually more energetically profitable to feed near the surface,” said Leigh Torres, an assistant professor and director of the Geospatial Ecology of Marine Megafauna Laboratory at OSU’s Marine Mammal Institute. “In this population of whales in New Zealand, they foraged more in areas where their prey was dense and shallow. MORE