Researchers mystified as solitary whales start swarming in huge numbers

20 Mar 2017

Humpback whale calf. Image: Tomas Kotouc/Shutterstock

Off the coast of South Africa, as many as 200 humpback whales – typically solitary creatures – have been swarming and researchers aren’t exactly sure why.

When a usually solitary creature like the humpback whale suddenly decides to go against its nature and swarm in huge groups, marine biologists are unsurprisingly eager to investigate.

According to National Geographic, a team led by Ken Findlay from Cape Peninsula University of Technology, Cape Town, began observing the peculiar behaviour during three different expeditions over the course of a four-year period.

Typically, humpback whales will form into groups of as few as three or four, but in these instances the team was observing as many as 200 or more swarming together.

To make the mystery even more perplexing, the swarms were occurring during spring. Typically, humpback whales visit the area during the winter months to feed on migrating fish.

While global events like climate change could be seen as an easy answer to solving this mystery – due to radical changes being observed in fragile climates – some theories put forward by the team suggest it could be something else.

In a paper published in PLOS One, Findlay and his team believe one answer could lie in a change in humpback feeding patterns, as the swarms have been observed hunting for prey.

Humpback whales South Africa

Whale supergroup off the coast of South Africa. Image: Jean Tresfon

Species in midst of a boom

This could mean either the availability of prey has changed or the behaviour of the whales has changed.

A second possible explanation – and a more positive one – is that our estimates of the number of humpback whales may be too low and that this recent change is a sign that the species is booming in numbers not seen since the whaling era of the 19th and 20th centuries.

Unlike a number of other marine species, the humpback whale is categorised by the International Union for Conservation of Nature as one of least concern, with over 60,000 of the animals known to researchers.

“These novel, predictable, inter-annual, low latitude feeding events provide considerable potential for further investigation of southern hemisphere humpback feeding behaviours in these relatively accessible low-latitude waters,” said the researchers.

Colm Gorey was a senior journalist with Silicon Republic