Why are these orcas killing sharks and removing their livers?

https://www.nationalgeographic.com/animals/article/orcas-great-whites-sharks-livers-south-africa?cmpid=org=ngp::mc=social::src=instagram::cmp=editorial::add=ig20230323animals-orcashedcard&linkId=206750866

Quote

When 19 shark carcasses washed up on the beach just outside her home in Cape Town, South Africa, last month, Alison Towner knew right away who had killed them.

The sevengill sharks—predators in their own right­—were all found in the same condition: missing their livers, which had been sucked out through a clean tear in their shoulders. The rest of their organs remained intact.

Such near-surgical precision is the hallmark of a pair of orcas known as Port and Starboard, who have been extracting livers from sevengills and great white sharks since at least 2015. Easily spotted thanks to their dorsal fins, which bend right and left (hence their names Starboard and Port), the two male orcas were seen in the area two days prior.

Yes. Orcas are killing sharks, making a tear in the shoulder, where they suck out their livers.

No mention of a nice chianti.