How blue whales plan their feed ‘outings’

The fact that they eat krill is not surprising – the whales are often shown in photos taking a gulp of water with krill, then spewing out the water with their giant-sized tongues.

Blue whales are what is referred to as “filter-feeders”.

We found that blue whales have a complex strategy of switching from conserving oxygen when prey quality is low, to intense foraging at the expense of oxygen when prey quality is high.

Blue whales can move at speeds of up to 30 miles per hour and dive as deep as 1,640 feet, lasting ten to 20 minutes underwater.

It is common knowledge that blue whales are the largest animals to have ever lived on this planet.

Jeremy Goldbogen, a marine biologist from Stanford University and co-author on the study stated that the lunge-feeding technique that is employed by the blue whales entails more effort, but “the increase in the amount of energy they get from increased krill consumption more than makes up for it”.

Researchers hope that their findings will help figure out how to protect the species, which is classified as endangered by the worldwide Union for Conservation of Nature.

Blue whales can eat as much as 4 tons of krill per day.

Research ecologist Elliott Hazen of the U.S. National Oceanic and Atmospheric Administration Fisheries’ Southwest Fisheries Science Center and the University of California Santa Cruz, has an explanation for this phenomenon.

A new study, published in Science Advances, focuses on the feeding pattern of the blue whales by providing examples of the blue whale foraging specializations that support the animals’ huge size.

These massive animals are by no means indiscriminate eaters (as we were previously led to believe). They sometime reach the conclusion that the patch is not dense enough to worth the effort.

The research team compared the feeding strategy of 14 tagged blue whales to 41 earlier tagged blue whales near the California’s coast, collating their gathered date with acoustic surveys that gauged the density of the krill they attack.

The researchers examined both krill density in each area and the maximum lunges taken by the blue whales per dive and calculated that these creatures are capable of optimizing both oxygen and energy for yielding the best possible results. This maximizes energy gain from the krill that the whale eats.

According to Ari Friedlaender, study investigator, such behavior proves that blue whales make educated decisions in order to increase the amounts of krill they ingest.

The study included information from more than 50 whales, using tags applied via suction cups and data on prey.

Hazen goes on to say, “The magic number for krill seems to be about 100 to 200 individuals in a cubic meter of water. If it’s above that, they’ll feed at very high rates and invest more effort”.

According to the IUCN Red List, the world oceans now house between 10,000 and 25,000 blue whales, which is about 5 percent as many blue whales as lived before the whaling industry brought them to the brink of extinction.