South Africa’s southern right whale population is falling, research finds

It’s the best part of Dr Els Vermeulen’s year: three days, up in an Airbus ECI20B, counting southern right whales in South Africa’s coastal waters.   

“The views are beautiful,” says the research manager of the whale unit at the University of Pretoria about the annual aerial survey of southern right whales between Nature’s Valley and Muizenberg. 

“We go down for 150m for the photos; for the search, we go up to 300m above sea level.” 

But it’s also depressing work. 

Numbers this year are the second-lowest in October in the past 32 years, after the extremely low numbers of 2016 (55 pairs). 

This year, 136 females and calves (68 pairs) were counted and photographed and “extremely low” numbers of 29 adult whales without a calf, bringing the total to 165.

The unit’s data indicates strong correlations between southern right whale prevalence along South Africa’s shores with climate conditions in the Southern Ocean and fluctuations in food availability. 

South African southern right whales have drastically changed their feeding locations in the past 20 years, “suggesting their previously productive feeding grounds have changed over time”.

The shift, Vermeulen says, may be an attempt to keep up with a changing ocean, but the changes may not be enough to ensure adequate body condition is obtained, hindering the success of calving and migration. 

Similar trends are being recorded in South America and Australia. 

“It’s worrying because southern right whales have come back from the brink. But we’re now looking at issues not as easily solved as whaling,” she says.