A recent study finds that great white sharks clear out when killer whales arrive:
“When confronted by orcas, white sharks will immediately vacate their preferred hunting ground and will not return for up to a year, even though the orcas are only passing through,” said marine ecologist Salvador Jorgensen of Monterey Bay Aquarium.
The team collected data from two sources: the comings and goings of 165 great white sharks GPS tagged between 2006 and 2013; and 27 years of population data of orcas, sharks and seals collected by Point Blue Conservation Science at Southeast Farallon Island off the coast of San Francisco.
In addition, orcas have been observed preying on great white sharks around the world, including near the Farallon Islands. It’s still a little unclear why, but the orca-killed sharks that wash ashore (one is pictured at the top of the page) are missing their livers — their delicious, oil-rich, full-of-vitamins livers.
Orca swim in a pod and will attack as a group. Great White just does not have a chance. Great White prefers warm blooded prey too. So young orca could be on the menu but the adults see that is not the case.
Where I was born (Durban, South Africa), they have netted beaches to protect swimmers etc. To administer this, they have an organization called “The Natal Sharks Board” (short for The Anti-Shark Measures Board), You can see Zodiacs and Boston whalers going out just after dawn off the beaches to service the nets. The sharks they catch are dissected and studied for science.
The nets are not continuous, rather they are staggered to allow fish etc in and out of the beaches, but they fish out large sharks. This reduction of the number of large (and therefore dangerous to swimmers and surfers), sharks from the local area is what prevents shark attack on the beaches, not isolating the beaches from everything.
You can visit their headquarters at Umhlanga Rocks, and take a daily tour. They have a rather good audio-visual presentation about how various sharks hunt, and how most shark attacks are mistaken identity, and accidental. They show a picture of a turtle from below, compared to a surfer paddling out, a snorkeler, compared to a seal etc.
They also have an awesome collection of things taken out of the stomachs of sharks they have caught.
The highlight of the tour is a narrated dissection of one of the sharks caught that day, with an explanation of their anatomy. An explanation of how their teeth are renewed, the Ampulae of Lorenzini (the electrical sensory apparatus in their snouts) and so on. One of the things I most remember is that sharks have a bi-lobed liver that can be up to a third of their live weight, so I can well see the attraction to a hungry Orca of a big great white.