Cape Town - Scientists who have been observing whale species say the population is returning to normal with an influx due to a balance in their ecosystem and because they are no longer being hunted or exploited.
Two months ago, Chris Wilkinson Technical Manager, Mammal Research Institute Whale Unit, Department of Zoology and Entomology at the University of Pretoria witnessed exactly this – a mass presence of orcas, also known as killer whales and super group humpback, up close and personal and said it was something scientist could only dream of.
It was an incredible and once in a life time experience for Wilkinson and his colleagues who have been researching and observing whale species across the country.
Wilkinson has a Master’s degree in Conservation Science and 15 years experience as a scientific technician.
For the past six years, he has been in Durban working for the Oceanographic Research Institute (fisheries-based research), and this will be his ninth year at the UP MRI Whale Unit and works alongside Dr Els Vermeulen who is a Senior Lecturer and Research Manager of the Mammal Research Institute Whale Unit.
The adrenaline, excitement and rush is clear when Wilkinson shares his encounter observing, not one, but six killer whales off Cape Columbine last month.
“We had a very close encounter off Cape Columbine on the 1st December 2023, where we were sampling a feeding super group of humpback whales, and as we had finished and were almost on our way home we saw a group of six killer whales harassing two juvenile humpback whales.
“This was incredible and something scientists dream about. Throughout the next 45 minutes, the killer whales had isolated one juvenile and were actively attempting to drown it by relentlessly pushing down and jumping on top of the nose of the humpback whale. More killer whales joined and after an hour of this, there were close to 20 killer whales (18 females or juvenile males, and two very big males).
“When the male arrived (after an hour) things happened very quickly, the biggest of the males pushed and drove the humpback whale under the water and all the other killers followed.
“There was an eerie moment of calm for close to five minutes where there had been all the action, there was not one whale on the service of blubber rising to the surface, that is the moment we assumed the humpback whale had met its fate.”
Wilkinson told that killer whales normally travel in smaller family groups, with one male, a couple of females and perhaps some young or calves.
“In this case of the predation on the 1st of December, we observed three waves of killer whales (possible family groups) that joined the attacker in a co-operative effort,” he said.
“We did notice in the beginning the females spent some time with the smaller killer whales showing them techniques and strategies, but as soon as the males arrived it all ended quickly.”
When asked whether he and his colleagues had noted an increase sightings of killer whales population visiting our coastlines, he said: “I think this is to be expected, mostly for two reasons; 1. Baleen whale species are no longer exploited and therefore whale populations are increasing.
“This increase in whale numbers will also attract more predators such as the orca (killer whale). Humpback calves and juveniles are a regular prey item for killer whales and it is impressive to see such top predators in action.
“Supergroups of feeding humpback whales are seen in the past decade or so along the South African west coast each year around November/ December. There have been regular occurrences of these super groups of humpback whales. We assume it is linked to the strong south-easterly winds that blow in the Cape during summertime.
“These winds cause up welling of cold nutrient-rich water, which comes into contact with long summer days and causes huge production of phytoplankton which in turn attracts swarms of krill. These krill swarms are what attract the group of hungry humpback whales who have only been migrating and calving, and have not eaten for six months.
“So this productive west coast system is a ‘pitstop’ for whales as they migrate back South to Antarctica.”
During his thesis he found that the East Coast humpbacks have been increasing at a healthy rate of 11.5% a year, and the increase rate is starting to slow down to between 7.4% to 8.8%, which may indicate that the stock is reaching its pre-whaling numbers.
genevieve.serra@inl.co.za