ORCA RESEARCH

Port and Starboard

By Aaron Barnes

The killer whale (Orcinus orca), whose scientific name translates to “belonging to the kingdom of the dead” or “whale from the underworld,” is one of the ocean’s most iconic, magnificent, and effective predators. Found in every ocean on the planet, killer whales live up to their namesake, preying on animals ranging from herring, as famously seen in Norway, to blue whales, as documented off the coast of Australia. Despite their ability to feed on a variety of prey, most killer whale ecotypes are known for their specialization in targeting specific types of prey.

Among the most globally famous killer whales, and arguably the best examples of this predatory specialization, are South Africa’s very own Port and Starboard. These half-brothers, named for their collapsed dorsal fins leaning left and right, have gained notoriety for their exclusive preference for elasmobranchs (sharks and rays) as prey. These oceanic celebrities are beloved by many, drawing crowds and excitement whenever they appear. I’ve even met killer whale enthusiasts who’ve flown to Cape Town just for a chance to see them! Their fame in the whale-watching world is unmatched.

Port and Starboard were first encountered in 2009 off the coast of Namibia, mysteriously appearing as fully grown adults with an apparent ability to target sharks—particularly their livers—as a primary food source. After this initial sighting, they vanished until 2012, when they were seen around Cape Town’s Cape Peninsula. Once again, they disappeared until 2015, but since then, they’ve become regular visitors to the Peninsula and other areas of the Western Cape.

It wasn’t immediately apparent that Port and Starboard preyed exclusively on elasmobranchs. Their unique feeding habits only came to light after seven-gill shark carcasses with peculiar wounds were discovered in 2015 and 2016. At first, humans were suspected of inflicting these wounds, but detailed examinations of tooth impressions revealed killer whales as the culprits. Globally, shark predation by killer whales was known, but this marked the first confirmed case of killer whales targeting shark livers—a highly energy-rich organ.

Shark livers are dense in calories and nutrients, often making up a quarter of a shark’s body weight and occupying most of its body cavity. A single large shark liver can provide enough calories to sustain an adult killer whale for an entire day. This incredible caloric payoff likely explains Port and Starboard’s focus on sharks.

What amazed researchers even more was the precision with which these killer whales accessed the livers. By gripping the shark’s pectoral fins and ripping open its chest area, Port and Starboard left other organs and most of the body untouched—a clear display of intent and skill. While this surgical feeding technique is now synonymous with the pair, back then, there was no clear evidence tying them to the crime scene.

Proving their involvement was no easy feat. Port and Starboard are elusive, with low-profile dorsal fins that make them difficult to spot, and most shark predations occur below the ocean’s surface. However, in 2017, their predatory prowess became unmistakable. They began targeting great white sharks—the apex predators of the ocean—with similar surgical precision. The carcasses of these white sharks, often missing their livers, washed ashore shortly after the duo was spotted nearby. Finally, in May 2022, drone footage captured Starboard and other killer whales preying on a white shark off Mossel Bay, conclusively proving the deadly duo’s modus operandi.

Today, Port and Starboard’s visits often leave a trail of shark carcasses, to the dismay of shark enthusiasts and researchers. Photographers and videographers have documented their hunts, further confirming their impact on South Africa’s marine ecosystems. Research has shown that the pair strategically targets shark aggregation sites, dramatically altering the predator-prey dynamics of these areas.

While their actions may frustrate some, Port and Starboard’s behavior is a testament to their adaptability, intelligence, and skill. For those of us who admire the ocean’s creatures, they are a marvel—a reminder of nature’s complexity and wonder.

References

Best, P.B., Meÿer, M.A. and Lockyer, C., 2010. Killer whales in South African waters—a review of their biology. African Journal of Marine Science, 32(2), pp.171-186.

Best, P.B., Meÿer, M.A., Thornton, M., Kotze, P.G.H., Seakamela, S.M., Hofmeyr, G.J.G., Wintner, S., Weland, C.D. and Steinke, D., 2014. Confirmation of the occurrence of a second killer whale morphotype in South African waters. African Journal of Marine Science, 36(2), pp.215-224.

Engelbrecht, T.M., Kock, A.A. and O’Riain, M.J., 2019. Running scared: when predators become prey. Ecosphere, 10(1), p.e02531.

Towner, A.V., Watson, R.G.A., Kock, A.A., Papastamatiou, Y., Sturup, M., Gennari, E., Baker, K., Booth, T., Dicken, M., Chivell, W. and Elwen, S., 2022. Fear at the top: killer whale predation drives white shark absence at South Africa’s largest aggregation site. African Journal of Marine Science, 44(2), pp.139-152.

Towner, A.V., Kock, A.A., Stopforth, C., Hurwitz, D. and Elwen, S.H., 2023. Direct observation of killer whales preying on white sharks and evidence of a flight response. Ecology, 104(1).

Towner, A., Micarelli, P., Hurwitz, D., Smale, M.J., Booth, A.J., Stopforth, C., Jacobs, E., Reinero, F.R., Ricci, V., Di Bari, A. and Gavazzi, S., 2024. Further insights into killer whales Orcinus orca preying on white sharks Carcharodon carcharias in South Africa. African Journal of Marine Science, 46(1), pp.1-5.