- The harmonic clicking of a "chatty" killer whale swimming off Fish Hoek in False Bay has been recorded in South Africa for the first time.
- Their distinctive calls can help scientists identify killer whale groups.
- While this killer whale won’t be winning any prizes for its tune, recent activity of its species in False Bay has scientists abuzz, thanks to a pair of shark-eating killer whales.
- For more articles, go to www.BusinessInsider.co.za.
The sounds of a "chatty" killer whale have been recorded in South Africa for the first time, off Fish Hoek in False Bay on Tuesday.
The sounds were captured by researchers Tess Gridley and Simon Elwen from Sea Search, a non-profit based in Muizenberg that focuses on research and conservation of marine mammals along the coasts of South Africa and Namibia. The pair were tipped off by local whale watchers.
“We have a local sightings group which is a bunch of keen whale watchers and operators. Somebody reported early in the morning that there was a killer whale in the False Bay area at around eight o’clock,” said Elwen.
“Dave Hurwitz, who runs the Simon’s Town Boat Company, a whale watching company, had his boat on the water and is part of a consortium that are all together trying to learn more about the animals and gave me a ring. I grabbed the equipment and ran out the door, luckily all our batteries were charged and managed to make it from Muizenberg to Simon's Town in about 40 minutes.”
Sea Search has been coordinating acoustic and biopsy research into killer whales for the last two years, working in collaboration with the University of Pretoria as well as Durham University in the United Kingdom.
“It was a male with an erect normal upright dorsal fin. We probably have it in the catalogue, and Hurwitz thought he recognised it from previous boat trips,” said Elwen. “It was quite unusual behaviour [to see]. Usually when killer whales are in the False Bay they tend to keep moving. It was very unusual to see they were staying in one area. The way it behaved we presumable it was probably feeding on something in the bottom – probably some reef associated fish or a ray or something like that."
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“This is the first documentation of orca vocalisations we think in South African waters. In general, killer whales are known for having a shared dialect. So, in groups they share a repertoire of call types,” said Gridley.
“As you can hear from the short clips we put up on our YouTube channel they can sound quite odd. The sound like little bursts and squeaks and whistles. We’re really at the beginning of our research of killer whales in South Africa and vocalisations. Which is why we are excited to get this data.”
The audio is important because you can identify different ecotypes from the calls that killer whales make.
“It’s the missing piece of the puzzle in our acoustics research. We haven’t had killer whale records form around our coast before. In terms of the creature’s classification, you need to get data in the area that you are interested in to be able to make the classifications. Killer whales like other dolphin species can learn their calls and they can be different in different areas. So, from a call perspective, it’s really important to get decent data from the area we work in,” said Gridley.
Researchers are also trying to collect skin samples from these animals for genetic analysis and, hopefully, fit satellite tags to a few animals to look at movements.
“We are trying to get more genetic samples of killer whales in South African waters to add to a global study. It looks like we have some high genetic diversity here in South Africa based on museum samples, but we have very few samples,” said Elwen.
From the skin samples, they can look at sex, relatedness, isolation, evolutionary history, and population structure. They can also use the stable isotopes of elements in the skin to look at what they've been eating, from sharks to sardines.
While this killer whale won’t be winning any prizes for its tune, recent activity of its species in False Bay has scientists particularly interested.
Until a few years ago, killer whales were a rare sight in South Africa, let alone Cape Town. But in 2015, several dead sevengill sharks were found by scuba divers at a popular dive site in the Table Mountain National Park marine protected area. The deaths of the sharks also coincided with a dramatic decline in great white shark sightings in False Bay.
Read | 'New' killer whales have moved to South Africa - and are feasting on local great white sharks
The mysterious deaths, as well as the decrease of shark sightings, was theorised to be the work of the now infamous Port and Starboard, easily identified by their not-erect dorsal fins. The shark-eating killer whales have been frequently spotted patrolling South African waters over 41 times.
“There is a very clear link between Port and Starboard and they definitely eat sharks. I have a photograph of Starboard with a shark in its mouth. The evidence from the Shark research team is that they are definitely eating them,” said Elwen.
Other killer whale groups have been known to patrol over wide distances from Cape Town to Mossel Bay and even up to Port Elizabeth.
“Over the last five years they’ve been seen a lot in False Bay particularly. Part of that is because we have people right next to the coast spotting them. The number of killer whales in False Bay have kind of gone up and down associated with broader environmental trends,” said Elwen.
A second school of thought puts the blame on environmental change.
“There are bigger issues at play. There is a short-term avoidance response from the sharks. Longer term and moving away from False Bay it is more linked to environmental change at a broader level. It’s not like there is a decrease in a population it is more like the population has shifted east,” added Elwen.
Little is known about why killer whales have moved into this part of the world, but answering the questions is all part of the work the team at Sea Search does.