2 killer whales slaughter 17 sharks in 1 day

Killer whales: Two floppy fins sticking out of the water, one to the left and one to the right.
Port and Starboard are the killer whales with floppy fins that are hunting sharks off the coast of South Africa and eating their livers. Image via Marine Dynamics.

Port and Starboard are the names of two infamous killer whales (orcas) that swim off the coast of South Africa. Their names come from their rare collapsed dorsal fins: Port’s bends to the left and Starboard’s bends to the right. The pair went on a killing spree last week, attacking and killing at least 17 broadnose sevengill sharks in a single day (February 24, 2023). The whales ate only the sharks’ livers and left their bodies to wash up on the beach.

This pair of male killer whales gained notoriety in 2015, when scuba divers found several broadnose sevengill sharks dead. Eventually, researchers fingered killer whales Port and Starboard in the deaths. Then, in 2017 and 2019, great white sharks were washing up on the coast with just their livers eaten out of their bodies. By 2020, the formerly hundreds of great white sharks in South Africa’s False Bay had nearly all moved out of the area. But, as proved last week at Pearly Beach, two hours east of False Bay, Port and Starboard are still at it.

Alison Kock, a marine biologist in Cape Town, South Africa, shared the news on Twitter.

Why eat just their livers?

Time and again, the washed-up carcasses of the sharks shows that the killer whales are just targeting the sharks’ livers. The killer whales are biting the sharks between their pectoral fins, yanking out the livers and leaving behind the other organs. The killer whales must have learned at some point where to find this tasty meal and remembered it, because they leave behind no bite marks on other parts of the sharks’ bodies.

But why the liver? Livers in sharks are large: They account for up to a third of a shark’s body weight. And, they’re rich in fat, packed with nutrients the whales need.

Video of killer whales hunting sharks

Last October, Kock was part of a team that published the first evidence of orcas killing great white sharks. In the peer-reviewed paper in the journal Ecology, lead author Alison Towner and the team shared images from drone footage that captured the killer whales hunting and eating the livers out of great white sharks. Christiaan Stopforth took the video, which you can watch part of here:

Killer whales are not a threat to humans

Despite the gruesome feeding frenzy off the coast of South Africa, killer whales pose no threat to humans. According to LiveScience, there is no record of a killer whale in the wild ever killing a human. A killer whale’s diet normally consists of seals, squid, fish and so forth. Humans are not on the list, although now it appears that sharks are.

On the other hand, four humans have died at the hands of killer whales in captivity. Three of those deaths were all due to the same killer whale, Tilikum, or Tilly. Tilly spent most of his life at Sea World in Orlando, Florida. The acclaimed documentary Blackfish chronicles the story of Tilly and the three tragic deaths.

Their floppy fins

Why are Port and Starboard’s dorsal fins floppy instead of upright? Simon Elwen at Sea Search answered that question for Shark Spotters at their Facebook page:

Male orcas are renowned for having extremely large, upright dorsal fins … Dorsal fins that are bent over or collapsed are relatively common in orcas that are in captivity, but only seen rarely in wild killer whales. In captivity, it is thought that the dorsal fins may bend over because the orcas are always swimming at the water’s surface, with the fin often sticking out of the water into the air … The fins are made from cartilage and are very heavy due to their size, and so without the support of water they are more likely to bend over.

In the wild, bent dorsal fins are most commonly associated with injury, such as an entanglement. However, although rare, there does appear to be some natural occurrence of bent dorsals among wild populations … One theory is that it could be diet related. And especially in shark-eating orcas such as Port & Starboard, it could be that they are not consuming enough calcium or other essential minerals for strong dorsal growth. Pollutants could be another possible cause, especially as shark-eating orcas are consuming prey that are at the top of the food chain and so … have higher levels of pollutants than lower order prey.

These two killer whales, anyway, are certainly living up to their name.

Bottom line: The killer whales Port and Starboard killed 17 broadnose sevengill sharks in one day off the coast of South Africa, dining on their livers and then letting the bodies wash ashore.

Source: Direct observation of killer whales preying on white sharks and evidence of a flight response

Read more: A new species of killer whale?

February 26, 2023

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