Whales migration patterns passed down from mother to child

The migration patterns of southern right whales are learned rather than instinctive, researchers have found.

Whales pass on their migration patterns to their calves. Image by Department of the Environment and Primary Industries / CC BY 2.0

The international team lead by researchers at Macquarie University found young whales learn the location of their feeding and breeding grounds by following their mums, rather than relying on an instinctive internal compass. Once they know, they follow these learned routes year after year returning to the same grounds.

The fascinating result of this learned behaviour is its effect on the genetics and population recovery of the species, Professor Robert Harcourt from Macquarie University says.  “What is interesting about the findings of this study is that they show that the migratory culture actually has an effect on the genetic patterns that we observe in both the summer feeding and winter calving grounds of Australian southern right whales.”

Researchers found the southern right whales that breed around the Great Australian Bight are genetically distinct from those that migrate through the waters along the south east coast of Australia. “If there was even a small amount of mixing occurring that would disrupt that population structure, but we find very strong population structure so that means they’re very much differentiated,” Professor Harcourt told ABC Hobart during a radio interview. Which means the whales you spot breaching off the waters of Warrnambool, Victoria, are unlikely to have crossed paths with those frolicking in the waters of King George Sound, Western Australia.

The migratory culture has an effect on genetic patterns of whales. Image by gailhampshire / CC BY 2.0

The study used data taken from an extensive collection of DNA samples gathered over 20 years. To gather the samples, scientists shot modified rifles containing a plastic dart at the whales that then dropped into the water to be collected by the researchers on the boat. And though southern right whales travel slowly and swim close to the surface, Professor Harcourt admitted, “it is actually quite easy to miss a whale when you’re shooting it from a boat moving in the water … I’ve missed a few, very embarrassing.”