Killer Whales - Orcas

While it's exceptionally rare to see Killer Whales in Algoa Bay, we have been very privileged to observe these wonderful animals along our coastline and we can only hope that with the cessation of whaling that they will increase in numbers and be observed more frequently.

There are at least nine main types of killer whales (Orcas) in the world, two in the North Atlantic, three in the North Pacific and four in the Southern Hemisphere and the list is growing! There are the so-called resident pods which feed mainly on fish and occur in a wide range of group sizes ranging from three to about 60 animals. Then there are the mammal-eating ones that are called transients. They occur in much smaller groups of between one and four animals although occasionally up to fifteen. These are the ones that I have been seeing along our coastline over the last twenty years. They seem to use a hunting method called passive sonar where they listen out for sounds made by other cetaceans and then use ambush tactics, communicating with each other once a kill has been made. This seemed to be the case on 27th January 2003 when we observed two adult female killer whales and a calf creeping up on 400 bottlenose dolphins cowering away in a sheltered bay at St Croix Island in Algoa Bay.

In the Southern Ocean, recent observations have revealed the possible existence of four types of killer whales. In all types the dorsal fin continues to grow in both sexes but with a delphinid shape, in females and juvenile males. In adult males the fin not only gets bigger but becomes more triangular in shape and can attain 1.8 metres in height. In males up to six metres the dorsal fin is about 10% of the body length while in males over 6 metres it is on average 18% of the body length. On the killer whale we observed the fin actually wobbled when the animal surfaced, and because it is not supported by bone or cartilage it can curl over to one side as often observed on captive animals. Males also have larger flippers and tail flukes than females as can be seen in the attached photos. Killer whales can often be confused with humpback whales as the underside of their tail flukes is sometimes also black and white like those of killer whales. Also, when a southern right whale lies on its side its tail often resembles the dorsal fin of a killer whale.

The Type A Killer Whale mainly frequents our shores off Port Elizabeth. There is increasing evidence of a second type A, which is smaller and so far unnamed, which has also been observed here. The largest males are almost nine metres long while the females reach almost eight metres. Most females seldom reach seven metres while 50% of males do. Males can weigh up to five and a half tones while females are smaller. They have a moderately sized white eye-patch. Around the Antarctic they prey mainly on minke whales. In our waters they prey predominantly on dolphins (I have observed them eating both common and bottlenose). Although they do prey on Cape fur seals they do so surprisingly infrequently considering that we have over two million of them in South Africa and Namibia. They also take penguins, cormorants and white-chinned petrels. There have been many reports of killer whales taking hooked tuna off commercial long lines on the Agulhas bank to such an extent that fishermen leave the area. Retaliatory actions by frustrated fishermen include shooting or the throwing of “thunder flashes”. There have also been reported attacks on southern right, humpback and fin whales. When attacking southern rights the killer whales try to split up the group or cow and calf pair while the whales try to group as close as possible together. Once the animals are killed the killer whales usually only eat the tongues which seems like a delicacy to them. In Plettenberg Bay in 2002 a male killer whale from a group of three killed a four metre great white shark. The male and female then came and displayed it to the boat based whale watching boat!

The group size of Killer Whales from the 627 sightings by long line vessels showed that all except one was of up to 13 animals. The exception was a group of twenty. In 93% of the observations the group size was up to six animals, the average being two. Other datasets shows 81% of the groups being up to six animals, the rest up to ten with an average of four and a half. Boat based whale watching operators reported between one and two calves present in ten of the 15 sightings. I have seen calves in all of my sightings although they are sometimes difficult to distinguish at first.

Type B Killer Whales inhabits inshore waters around the Antarctic and is closely associated with continental pack ice. The eye patch is twice as large as type A and it has a grey cape on the body behind the dorsal fin. They prey mainly on seals but also on minke and humpback whales.

Type C Killer Whales also inhabits inshore pack ice in the Antarctic. The eye patch is diagonal and slopes down at the front. They are smaller than type A, the males attaining six metres and the females slightly less. They feed mainly on fish.