TOURIST boats on whale-watching trips are going too close to mother whales with calves, raising concerns among researchers and officials about possible stress on the young animals.
And the reason boats are breaking the law appears to be that the number of southern right whales without calves – which boats with permits are allowed to approach within a certain distance – has dropped over the past five years. Researchers are not sure why.
These whales are known to researchers as “unaccompanied adults”.
Whale scientist Ken Findlay, who runs the helicopter survey which counts the number of southern rights between Nature’s Valley and False Bay every year, said overall the population was increasing at a rate of about 7 percent a year.
Findlay, from the Mammal Research Institute Whale Unit, said before 2010 the number of “unaccompanied adult” whales was roughly the same as the number of whales with calves.
But given that the overall number of southern rights was increasing in the survey area, the drop in the number without calves was likely to be because these had moved out of the survey area.
“It can only be a change in distribution, and might be that those that are not breeding have moved to the West Coast where there is quite a lot of food because of upwelling,” Findlay said.
“But the concern is with these unaccompanied adults moving elsewhere, it puts pressure on the cow and calf pairs from whale-watching boats.
“Whale-watching boats may not approach cow and calf pairs, they must move away if they see these.
“But if there are not many groups of whales without calves, it must put pressure on the cow and calf pairs.
“We are getting reports that this is happening in the Walker Bay area and it is a concern.”
Findlay said keeping boatloads of tourists away from breeding whales was based on the precautionary principle.
This principle holds that if there is a risk that an activity may harm the environment, precautionary measures should be taken, even if cause and effect has not been established scientifically.
Findlay, who begins this year’s helicopter survey on September 28, would like to extend the helicopter survey to include the West Coast to see if the whales without calves have indeed moved west – but funding only just covers the region from Nature’s Valley to Muizenberg.
Mike Meyer, of the Department of Environmental Affairs, confirmed yesterday that there had been reports of whale-watching boats approaching cow and calf pairs.
“We are not sure how much this is happening, but if it is a significant number, then we do need to look at it and evaluate what we need to do,” Meyer said.
This is the 37th consecutive year that the University of Pretoria’s whale unit will be conducting the survey, with a permit from the Department of Environment Affairs.
Each cow and calf pair is photographed, analysed and catalogued.
The unit has a catalogue of about 2 000 recognisable adults.