Blue whales are the largest creatures on Earth, and new research suggests that in order for them to maintain their monstrous size they must use ultra-efficient foraging methods.
These foraging methods must optimize the energy the whales gain from the krill they feast on while conserving oxygen during dives, the NOAA Fisheries, West Coast Region reported.
It has been widely believed that large filter-feeders such as blue whales graze indiscriminately and often, this new research suggests their foraging methods are more complex than we thought. A team of scientists tagged blue whales and founf they target the densest, highest-quality prey, allowing them to maximize their energy gain. These findings could help us better understand how to conserve the endangered species.
"For blue whales, one of our main questions has been: How do they eat efficiently to support that massive body size," said Elliott Hazen, a research ecologist with NOAA Fisheries' Southwest Fisheries Science Center and lead author of the research. "Now we know that optimizing their feeding behavior is another specialization that makes the most of the food available."
When feeding, blue whales take in enormous amounts of water and filter out the tiny krill it contains before releasing it. The process requires large amounts of energy that must be replenished often. To discover how blue whales keep up with their energy requirements, the researchers compared the foraging of 14 tagged blue whales to 41 previously tagged blue whales off the coast of California. They compared this data with acoustic surveys that measured the density in the water. The data showed that when krill were less dense in a given area, the whales fed less frequently to conserve oxygen and energy. When krill densities were higher, the whales practiced "lunge-feeding" more frequently, allowing them to consume more krill per dive while and obtain as much energy as possible.
"Blue whales don't live in a world of excess and the decisions these animals make are critical to their survival," said Ari Friedlaender, a principal investigator with the Marine Mammal Institute at Oregon State University's Hatfield Marine Science Center and co-author on the study. "If you stick your hand into a full bag of pretzels, you're likely to grab more than if you put your hand into a bag that only had a few pretzels."
The researchers believe these new insights into blue whale behavior could lead to the realization of new ways to protect the endangered species.
"If they are disturbed during the intense, deep-water feeding, it may not have consequences today, or this week, but it could over a period of months," Friedlaender said. "There can be impacts on their overall health, as well as on their fitness and viability for reproduction."
The findings were published in a recent edition of the journal Science Advances.
