The photographer and drone pilot Carlos Gauna, alias The Malibu Artist, is well-known for capturing remarkable sequences of great white sharks and other marine life off the thronged beaches of Southern California. Among those he posted in November appears to capture the aftermath of an intriguing shark-on-shark predation event:
In the video compilation, The Malibu Artist shares footage of thresher sharks breaching off the beachfront – a behaviour for which both common and pelagic threshers are well-known, and which, depending on circumstances, has been linked to evading threats, trying to shed parasites, and pursuing prey (not to mention fighting an angler’s hook).
He then highlights a shot of a great white cruising with what appears to be a thresher’s scythe-like tail streaming out of its jaws.
Common threshers grow to a very respectable size: Adults may attain six metres (20 feet) and some 454 kilograms (1,000 pounds). Much of the impressive length, though, derives from the resplendently long upper caudal fin, which gives the thresher its bullwhip of a tail and is used to stun small schooling fish and other prey. Predation on the species isn’t all that widely documented, though a 2005 study recorded several instances of New Zealand orcas hunting threshers ranging from about 1.5 metres (5 feet) to 3 metres (about 10 feet) long, and here in Southern California, sea lions have been observed on multiple occasions tearing into threshers.
This recent drone footage comes from a place where young white sharks and young threshers rub shoulders (fins?): the Southern California Bight. This subtle embayment of the western coast of North America stretches some 560 kilometres (about 350 miles) between Point Conception, California and Cabo Banda, Baja California, Mexico. The Bight is an oceanographic and ecological mixing-ground, where the cold, oxygen-rich California Current flows south on the western margin, while closer inshore, the warmer, saltier, lower-oxygen equatorial waters of the California Undercurrent and, above it, the California Countercurrent roll northward.
The Southern California Bight is a major shark hub, not least because the shallower coastal waters over its continental shelf appear to serve as a nursery for multiple species: among them shortfin makos, blue sharks, and, yes, common threshers and great whites. Adults of these species ply the Bight’s offshore waters, but are less abundant in the coastal zone, which makes it, apparently, a safer place for pups and juveniles.
But, of course, we’re dealing with some size – and some trophic – discrepancies among these toothy youngsters. A juvenile white shark is not exactly a small animal. And in the Bight, fellow elasmobranchs are very much on the menu: Rays such as round stingrays and bat rays are favoured foods (as The Malibu Artist’s video also touches on), but, as Dr. Chris Lowe, the director of the California State University Long Beach Shark Lab told me, essentially any of the other coastal sharks – from soupfins and leopard sharks to those young threshers – “are all fair game, just less abundant than the rays.”
Other Sharks on the Great-White Menu
Indeed, while white sharks generally undergo a dietary transition when they hit about 2.5 to 3 metres (8.2 - 9.8 feet) in length and several years of age, often increasingly targeting marine mammals such as pinnipeds and cetaceans, good-sized fish – other sharks included – remain very much on the menu. (Lowe pointed out that, while the common perception is of the white shark as a super-lethal killer of seals and sea lions, such fleet, agile, and toothy mammals aren’t necessarily easy pickings. “There are some [white sharks] that are really good marine-mammal hunters, and some that are so-so,” he said. “I think it takes years to develop the skills.” And, he pointed out, a lot of marine-mammal ingestion – especially for juvenile white sharks – takes the form of scavenging.)
Studies in South Africa’s Mossel Bay suggest mature white sharks there, despite a large colony of Cape fur seals, may actually feed more heavily on other sharks, such as smoothhounds. Bronze whalers (aka copper sharks), a type of requiem shark, have been found in the stomachs of South African great whites; after white sharks abandoned a well-known year-round hangout in Gansbaai, Western Cape Province – apparently due to attacks by shark-liver-loving orcas – bronze whalers increased there, perhaps due to the reduced predation risk from white sharks.
And a few months ago, meanwhile, a paper in Frontiers in Marine Science documented the likely consumption of a full-grown, satellite-tagged porbeagle (a mackerel shark, like the great white and the thresher) in the Northwest Atlantic by what researchers suspect was probably a big female white shark.
White Shark Nursery
But back to the Southern California Bight: In the shallows of its nearshore zone and continental shelf, juvenile white sharks – including neonates, “young-of-year” (YOY) animals, and older individuals generally under 3 metres (~9.8 feet) long – find safer refuge from bigger sharks (not just great whites, but also makos) as well as the rich piscivorous pickings they prefer. But another underlying reason the Bight is a great-white nursery is probably the relatively balmy temperature: Although white sharks are, roughly speaking, warm-blooded – they’re regionally endothermic, to be exact – neonate and YOY sharks, because of their smaller size, are less efficient at internally maintaining body temperature, and thus more thermally limited than their older and bigger counterparts.
(A 2021 Scientific Reports article on which Lowe was a co-author explored the possibility that the unusual appearance of juvenile white sharks in Central California’s Monterey Bay – hundreds of kilometres north of the Southern California Bight nursery – beginning in 2014 may have been due to a regional marine heatwave, and could be a harbinger of what’s to come with ongoing climate change.)
In the Bight, juvenile white sharks commonly congregate at particular “aggregation sites,” such as off Carpinteria and Del Mar Beach, for days, weeks, or months at a time. These aggregation sites, however, aren’t necessarily permanent gathering places, as Lowe told me. “We know those hotspots go cold, and then new hotspots form,” he said.
The Shark Lab is currently researching the underlying cause of those patterns, with a forthcoming paper looking at prey densities in Southern Californian great-white aggregation sites vs. non-aggregation sites. Evidence suggests aggregation zones show lower numbers of such go-to shark chow as stingrays and surf perch. Maybe juvenile great whites assemble where such fish are abundant, and then basically burn through the prey base, eventually causing them to abandon the sites and seek out new ones.
Lowe told me another facet of current research is why there appear to be two geographically segregated sub-populations of juvenile white sharks in the Southern California Bight: one mainly clustered at the inshore aggregation sites, the other farther offshore (though still in fairly shallow water) and roaming more widely over the continental shelf. An in-progress paper Lowe’s involved with will summarise a dietary study indicating the inshore juveniles are mainly feeding on coastal prey such as stingrays, small sharks, surf perch, and croakers, while their offshore counterparts are probably eating more bonita, anchovies, sardines, and the like.
These young white sharks off Southern California often move south in winter to the coastal waters of Baja California, including another nursery zone at the equatorward edge of the Southern California Bight, Bahia Sebastián Viscaíno. Some, however, appear to occasionally overwinter off Southern California.
Older Great Whites
Full-grown white sharks in the Northeast Pacific, meanwhile, tend to show up along the west coast of North America – including the hotspots of Central California and Baja’s offshore Guadalupe Island (where the truly massive great-white matriarch nicknamed “Deep Blue” was first identified) – between the late summer and early winter, targeting rookeries of high-value, blubbery pinnipeds such as sea lions, elephant seals, and fur seals.
They then head offshore for the rest of winter and and through spring: some all the way to the Hawaiian Islands, but most to the still-mysterious, so-nicknamed “White Shark Café” in the open subtropical ocean between Hawaii and Baja California. Scientists are still trying to figure out what great whites are doing way out there in the mid-ocean, though studies show – contrary to early assumptions that the zone was something of an ecological “desert” – that there are abundant populations of pelagic squid and fish in the Café to sustain them. White sharks there show intriguing diving patterns, which may be related to tracking this prey, but could conceivably also indicate mating behaviour.
It’s not terribly common to see such mature white sharks cruising close to shore in Southern California. Lowe pointed out a key difference between these coastal waters and another hot-and-heavy white-shark realm on the other side of the US – Cape Cod, Massachusetts – is the pinniped setup. The temperate beaches of Cape Cod are really only heavily peopled for a few months in summer, and otherwise the Northwest Atlantic’s resurging population of grey seals as well as harbour seals have them mostly to themselves. And those seal hangouts therefore have once again become magnets for adult white sharks.
By contrast, the balmier strands of Southern California are more of a year-round draw for surfers, paddleboarders, and sun-worshippers, and that busyness doesn’t leave a ton of room for pinnipeds (though there are some haul-outs along this coast). That means fewer big white sharks of the sort that come close to shore farther north along the California coast, at places such as Año Nuevo (a major rookery for the northern elephant seal).
The Channel Islands
But the Southern California Bight also encompasses the archipelago of the Channel Islands, partly protected in Channel Islands National Park and the Channel Islands National Marine Sanctuary and boasting a low human footprint. And the Channel Islands host significant pinniped haul-outs (“just loaded,” as Lowe puts it), with four regularly breeding species – northern elephant seals, California sea lions, northern fur seals, and harbour seals – and occasional sightings of Steller sea lions and Guadalupe fur seals as well. The westernmost of the Channel Islands, remote San Miguel Island, is reckoned to support north of 70,000 California sea lions and 50,000 elephant seals as well as smaller numbers of breeding fur seals and harbour seals.
The Channel Islands are “where we see a lot of our teenage white sharks go,” Lowe told me. As populations of marine mammals off Southern California build back up from the days of overhunting, such subadult white sharks – edged out of the established hunting grounds of full-grown great whites, such as the fabled Farallon Islands off San Francisco, and honing their prowess with larger prey – might be the first to seek out new (or restored) buffets, such as the Channel Islands, which, Lowe postulates, could be “the new Guadalupe Island, the new Farallons.”
California Threshers
The common threshers of the Northeast Pacific, meanwhile, are thought to form a single population with a range from British Columbia south to Baja California, with the greatest density in the Southern California Bight. It appears that the foundation of the local thresher diet – for the offshore adults and the inshore juveniles – is the northern anchovy, which thrives off the Bight’s rich plankton resources.
Foundation of the largest commercial shark harvest in California, the common thresher is targeted along with swordfish in the regional drift gillnet fishery. Indeed, catch data from commercial fishing operations helped identify the Southern California Bight as a thresher nursery.
Drones & Shark Research/Conservation
The videos posted by The Malibu Artist – from that thresher-munching great white to other highlights, such as a recent compilation of shark/dolphin encounters – are examples of the potential aerial drones have when it comes to low-impact wildlife observation. (Which is definitely not to say that drones, operated unethically, don’t also have the potential to be high-impact when it comes to animals.) From sea turtles dodging tiger sharks to major gatherings of humpback whales, these flying robots have certainly been capturing some remarkable sequences and behaviours over the past decade or so.
Lowe and his team certainly take advantage of drones in their research, not least in finding sharks to tag – a task that formerly required more expensive airplane or helicopter flights. Drones have also helped demonstrate just how much juvenile white sharks overlap with human water users off Southern California beachfronts, among the most heavily used in the world. Given how many people and how many sharks are sharing these waters, it’s all the more remarkable how few shark bites are logged here: a likely contributing reason being that surfers, paddleboarders, swimmers, and waders are generally bigger – and using a different part of the water column – than those young great whites’ typical nosh.
A major thrust of the Shark Lab’s work is public outreach and education; Lowe told me a big priority is getting as much of the scientific information they collect out to the public. Part of that clientele are Southern California lifeguards, who want to know where sharks are and whether they need to close a beach in the wake of one of the (again, super-rare) shark bites. Lowe said a current effort is improving shark awareness signage – informed by a consulting psychologist who specialises in fear, with the idea not to scare beachgoers and water users, simply alert them. (Speaking of fear, another forthcoming paper Lowe’s a part of will show that folks who’ve actually encountered sharks in the water without a negative result become less fearful about sharing space with them in the future.)
Watch for those forthcoming papers (and explore previously published research) at the Shark Lab’s website, where you can also learn more about the group’s California Shark Beach Safety Program and other outreach efforts – and support this long-running research facility, established back in 1966 and facing a tricky budget situation in 2025.
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