Two Orcas named Port and Starboard are believed to be behind the first recorded carcass of a copper shark (also known as bronze whaler shark) last week in the Walker Bay area.
Port and Starboard made international headlines in May 2017 when they were linked to the killing of several great whites, as well as sevengill sharks in South Africa.
The carcass of the three-metre-long bronze whaler shark was found on Wednesday, 5 February after it washed up on Grotto beach. Resident Riekie Louw spotted the carcass on the beach and alerted The Village NEWS, which in turn contacted the Dyer Island Conservation Trust (DICT) team, who collected the dead shark.
“The female shark was torn open at the torso with its liver and heart completely removed. The previous day, Port and Starboard were observed in False Bay, 100 km west of Hermanus. This orca pair is confirmed to have predated on both sevengill and white shark species in this manner off the Western Cape coast, but this was the first copper shark carcass to be linked to them. The pair is known to specifically tear open their shark prey to extract the large lipid rich liver and discard the body,” said Alison Towner, a DICT biologist.
“We can confirm the presumption of orca predation, as the injuries were similar to other shark species predated on by them. There were also raker marks (tooth impressions) of killer whales on the carcass.
“This behaviour is being observed more frequently in South Africa, causing ripple effects in certain shark species’ distributions, as well as potentially influencing the ecology of the Western Cape coastal areas, because of sharks avoiding their traditional aggregation sites for extended time periods,” said Towner.
Louw said she went for her daily walk on Grotto last Wednesday when she happened upon the carcass just 100m from the main beach. “When I took a closer look and saw the gaping hole, I immediately thought this must be an orca attack. I read the stories in The Village NEWS in 2017 and remembered that these wounds looked exactly like the pictures I had seen. I instantly went back home to fetch my camera to take pictures in order to let the newspaper know,” she said.
It has been confirmed that the pod of orcas that were observed interacting with white sharks in Mossel Bay and Knysna during early November and February are not Port and Starboard, as their dorsal fins are different.