The merciless apex predators of Algoa Bay

The 2nd March 2014 started like any other day in Algoa Bay at that time of the year, nice and hot and not too much wind. There were only four guests on whale watching vessel Orca 2, the minimum required for a cruise out to St Croix Island in the Proposed Greater Addo MPA. It was only by chance that we managed to find a fourth person to make up the group; otherwise it would have been another day on the horrible old computer.

We approached the St Croix group without having seen anything exciting, bar the odd gannet and cormorant. We had just rounded Brenton Island and were heading towards St Croix when one of the lookouts shouted from the viewing platform that they had seen “a large fin sticking out the water”. We immediately sped off in that direction and to our great excitement we closed in on a male killer whale. Using Orca 2 as a ruler, which is 10.5 metres long, we estimated its size at between 7 and 8 metres. This was slightly larger than the male sighted previously, as its dorsal fin was larger and more triangular in shape.

The male entertained us for our allotted twenty minutes (the maximum time you can stay with a whale due to permit constraints). During this time he was heading inshore towards the third island in the group, Jahleel Island, which lies just off the new commercial port at Coega. He came close to the boat on numerous occasions but never entertained us to the spectacular show of breaches and tail slaps like the last time we found a pair with their calf. He obviously felt no reason to be threatened.

We moved away from the “sea panda” towards Jahleel as one of the lookouts had spotted a school of about 100 Indo-Pacific bottlenose dolphins, Tursiops aduncus. They were minding their own business and moving along at a leisurely pace. The killer whale was a few hundred metres away and did not seem to take much notice. However, as we took more interest in the dolphins, he seemed to do likewise. It was a bit like playing with a child’s toy, which in turn spurs their interest in needing it urgently. This went on for about ten minutes.

All of a sudden the time had come for which everyone had been waiting. The killer whale suddenly put on a burst of speed, took a few long, deep and fast breaths and came towards us at full speed. He dived down to presumably where the last dolphin was frantically trying to catch up with the school. There was an explosion of water above the one sided battle which raged on below for about forty seconds. As suddenly as it started it was soon over. We edged Orca 2 closer and observed the very dead dolphin with just its head protruding above the surface as can be seen in the attached photographs. The killer approached and proceeded to push the lifeless soul around with his massive body. At no stage did he attempt to bite or eat it on the surface. This went on for about four minutes. He then dived, charged up, grabbed it in his massive jaws and disappeared beneath the surface. The dolphin was not seen again.

It is very interesting that the killer whale killed the bottlenose dolphin and then left it; you would obviously see blood and/or an oil slick if it had fed on the carcass. It would have also taken quite some time. They have been known to do this sometimes (kill something and not eat it) but it is not clear why. This behaviour has been observed by Juan Copello and the Fallows at Punta Norte, Peninsular Valdez in Argentina. This is where the killer whales beach themselves in pursuit of young sea lions and elephant seals. It is also interesting that the killer whale managed to kill a dolphin so easily on its own. It is clearly not always necessary for them to hunt together, but they are probably more successful when working as a team.

After this the whale started paying more attention to the boat and its merry band of excited tourists than the apparently “disappeared” dolphin.

This is in stark contrast to the observations that our equivalent in the Cape, Dave Hurwitz, the owner of the Simonstown Boat Company, related in his story of killer whales hunting long-beaked common dolphins in False Bay. Here the killers actually hit the dolphins clean out of the water from below and even breached to land on the fleeing animals.

Also in False Bay, Chris and Monique Fellows have observed killer whales pursue long-beaked common dolphins and also simply catch them without a breach. It was just the surface oil slick, gulls and the smell that gave the successful kill away. They have also seen them pursue single dolphins as well as full blooded breaches into schools, striking the dolphins on the surface as the killers raced up from below. At most of their observations of predation, the actual feeding was subsurface. All their predation sightings were on long-beaked common dolphins and not Indo-Pacific bottlenose dolphins like in Algoa Bay.

Killer whales sightings in Algoa Bay are incredibly rare, as they are elsewhere along the coast. In my 33 years of going to sea I can count their sightings on my hands, scant reward for someone who spends more time than most in the “Bay of Plenty”.

If anyone spots killer whales in the vicinity of Port Elizabeth, they are to please call Ellie Bottomley, the manager of Raggy Charters on 073 152 2277073 152 2277 or Lloyd Edwards, the owner on 084 552 2277084 552 2277.

Once we have made a positive identification you are welcome to join Raggy Charters on our whale watching boat at no cost in order to get close up footage. Any information and photos will be passed onto the relevant marine whale scientists. We have the only boat based whale watching permit for Algoa Bay which allows us to engage in close encounters with cetaceans.

Thanks also to Ryan Reisenger for his input and comments. He is busy with his PhD on killer whales at Marion Island.

Written by Lloyd Edwards and Ellie Bottomley, Seaview: 28th March, 2014.
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