Farallon Islands is an important feeding area for one shark species.

Observations of predation on pinnipeds by White Sharks have been regularly recorded on a seasonal basis in the area between 1970–2025 through standardised visual surveys occurring from the island’s highest peak (Ainley et al. 1981; Klimley et al. 1992; Brown et al. 2010). The island hosts large breeding populations of California Sea Lion Zalophus californianus and Northern Elephant Seal Mirounga angustirostris, known prey of White Sharks, particularly during the boreal autumn (September–November) when juvenile Northern Elephant Seals are abundant (Pyle et al. 1996; Klimley et al. 1992). Predation events on each species are observed every season (Brown et al. 2010; Tietz 2026). On average, 31.9 ± 17.5 predation events are observed annually from the standardised visual surveys (Tietz 2026).

Since the early 1980s, dedicated boat-based White Shark surveys have also been conducted annually at Southeast Farallon Island from September to December to photo-identify individual White Sharks and deploy acoustic and satellite tags. Surveys are weather-dependent and typically occur at least weekly during this period. Acoustic receiver effort has been variable in this area, with consistent effort from 2006–2015, and variable effort up to 2026 due to logistical constraints, though a receiver currently remains in place at the island. Residency measures were calculated for each year of an individual shark’s tag deployment period, with ‘number of days detected at a site’ divided by 365 days.

These efforts have found that White Sharks regularly and predictably use this area during their annual migration between mid-August to late-December (Jorgensen et al. 2010; Andrzejaczek et al. 2025). From 2006–2022, 355 sub-adult and adult White Sharks were tracked with acoustic tags amounting to over 760,000 detections on a coastal array of receivers (Andrzejaczek et al. 2025). Of these, 19.4% of detections were at the Farallon Islands, with an average annual residency rate of 0.10 ± 0.08 per individual at this site. For sharks tagged at the Farallon Islands and tracked for longer than a year (n = 37), 77.8% of all days detected were at the Farallon Islands indicating repetitive site use by a number of individuals (Andrzejaczek et al. 2025).