Scientists might finally know where all the baby blue whales are

Scientists might finally know where all the baby blue whales are and the answer is shocking.

The mystery surrounding blue whale calves has stumped experts for decades and there have only been two recorded examples in human history and both were from decades ago.The blue whale is also world’s largest animal, so how comes the youngsters are never spotted?

The critically endangered species is rarely seen during its early years. Blue whales give birth every two to three years and the births are clearly very stealthy as the rate of sightings for blue whale mother-calf pairs is just 3.1 per cent.

Researchers generally believe that low foetal survival, low calf survival and low birth rates as well as separation from the mother are likely reasons for why so few calves are spotted which has sparked concern for the future of the species.

However a new study has put forward a theory on why blue whales manage to evade public view. Published in the journal Endangered Species Research, the potential reason may be due to the humans trying to find them, rather than the animals themselves.

The research suggests the reason calves are rarely spotted might be because, wait for it, researchers prefer summertime to study congregations of the massive animal.

A blue whale mother and calf swim togetherDiane Gendron/Mexico National Polytechnic Institute

An aerial image showing the close association between a blue whale mother and her calf Leigh Torres/Oregon State University

The young whales are born in autumn and winter and weaned before they return to feeding areas, the study’s co-author, Trevor Branch from the University of Washington, explains.

Blue whales migrate during the summer to feed in colder regions where krill is plentiful, with one location being the waters off California. The animals return to warmer regions, such as the Gulf of California and the eastern tropical Pacific in winter, when the time comes to give birth.

Seven months later and measuring over 16 metres in length, the calves are weaned and stop associating with their mothers. “Blue whales produce calves or give birth shortly after departing their summer feeding grounds and wean their calves seven months later, just before they return,” Dr Branch explains.

This could explain why the majority of researchers who search for the animals in the summer rarely see blue whale mothers with calves.

Dr Branch combined and assessed data from field studies and biological information from historical whaling records.

"This new idea provides an alternative explanation for why some blue whale populations appear to produce very few calves: it's not a failure of calf production, it's because fieldwork in those populations is understandably concentrated in easily accessible summer feeding areas," Dr Branch said.

“These results suggest that the mystery of the missing blue whale calves can largely be explained by mothers calving immediately after leaving summer feeding grounds and weaning on their return."

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