Los Farallones

Dispatches from Point Blue’s field station on the Farallon Islands National Wildlife Refuge

It’s shark season at the Farallon Islands!

written by Jim Tietz, Farallon Program Biologist

Every fall, the white sharks return to the Farallon Islands from their annual migration to the middle of the Pacific Ocean. We typically see the first shark predation event during late August, and then the number of predations increase through September to when they peak in October. The sharks come to the Farallones every fall, and other places along the California coast, to feed on pinnipeds (or seals and sea lions). The two species of pinnipeds they hunt the most in California waters are northern elephant seal and California sea lion. Sometimes the sharks will take advantage of an already dead carcass and scavenge it. To determine whether the sharks killed their prey or are scavenging something dead, we look for blood in the water during any feeding event – blood indicates that the prey species was alive when the shark initially attacked it. The sharks feed on pinnipeds during the fall to fuel their migration back to the middle of the Pacific in December and January.

On October 1st, we got to watch this white shark scavenging a carcass near East Landing. It took it about 15 passes to consume the whole carcass. Photo credit: Nick Asreen


On October 1st, we spotted this sea lion carcass floating near our East Landing crane while we were conducting a training. This Western Gull is hoping that a shark will come along and bite it into smaller pieces, so it can get a few morsels. Its wait was not in vain. Photo credit: Nick Asreen


A white shark making another pass to scavenge a carcass on October 1st. Photo credit: Sam Darmstadt


On October 6th, we spotted a shark predation in progress at Fisherman’s Bay. This bleeding sea lion was presumably bitten by a white shark, which was waiting underwater for it to bleed to death. Photo credit: Emily Ford