Killer Whales linked to shark deaths in Gansbaai

19 shark carcasses have washed ashore, torn apart, on Pearly beach near Gansbaai in the Western Cape since last week, with the latest washing ashore on Sunday morning.

Picture: Getawy gallery

‘The carcasses were sighted by residents and the Marine Dynamics Conservation Trust was called to action,’ reported the news.

Residents reported carcasses on the beach, prompting the Marine Dynamics Conservation Trust to investigate. Necropsies by scientists Alison Towner and Ralph Watson revealed that two killer whales, Port and Starboard, were responsible for at least 19 shark deaths, including five white shark predations in the Gansbaai area. The killer whale pair has been seen more frequently along the coast in recent years, leading to speculation that their presence may be driving away other shark species.

Read: Where did the Cape’s great whites go? A new study has the answers

The sharks that washed ashore were identified as 18 sevengill sharks and one small spotted gully shark. Every shark had visible orca tooth impressions, or rake marks, on their bodies. All but one of the sevengill sharks were missing their liver, and most had their stomachs missing too. The stomach contents of the sharks that did have them contained bony fish and Cape fur seal, which are preyed upon by sevengill sharks.

The male spotted gully shark, which was less than one meter long, was also missing its liver and head and had visible rake marks on its body. According to Watson, this was the first confirmed instance of orcas preying on this species, demonstrating their ability to handle smaller sharks than previously thought.

Towner, who is studying the decline in white shark sightings in the area due to killer whale predation, found this to be the most significant number of sharks to wash up in Gansbaai and the first time sevengill sharks had been found there due to orcas. Following the recent feeding frenzy, the orca pair was last seen off Mossel Bay.