On a recent Saturday morning, fog and heavy winds over Tomales Bay subsided for just enough time to allow Scot Anderson and Paul Kanive to board a 17-foot Boston Whaler and jet out to where the bay meets the sea, an area known to some scientists and divers as “shark alley.” They were in pursuit of one of the Pacific Ocean’s apex predators, the white shark.
Great white sharks? They laugh, “That name has come from entertainment. They are white sharks to us.”
With Dillon Beach and its popular surfing spot visible from the boat, the idea that these enormous creatures swim so close to people was stirring. “It’s hard to get people away from relating white sharks to biting people,” Scot said. “There are several threats to white sharks. A big one is people just wanting to kill them. They think the only good shark is a dead one.”
Scot is a white shark expert with over 25 years of experience. Growing up in Tiburon, he spent hours in the library reading about sharks, and he came to realize there were inconsistencies in the research.
“I started to wonder why nobody knows about their behavior,” he said. “How come one source says this and another says that? Talking to fisherman, I found the stories were all the same—they would see giant sharks for a brief moment before they disappeared.”
Later, as a bird bander on the Farallon Islands, he would spend his time staring at the water. Hours of observation led to sightings of the sharks going up to logs or jumping out of the water. Their unexplained behavior led him to seek answers that hadn’t yet been written down.
Paul has a Ph.D. in marine ecology and recently published his dissertation on white shark population trends in the area. At the beginning of his career, he worked on a pollock fishing boat as a National Oceanic and Atmospheric Administration fisheries observer; one day, some salmon sharks got caught in the boat’s nets and were hauled aboard.
Back then, there were no protections for any shark species and they were caught and killed without regulation, he said. The captain laid out the sharks, which Paul describes as beautiful and multicolored, and immediately sliced off their gills. When Paul asked why, the captain responded, “Because these guys are my competition.” Paul took the next opportunity available to pursue research.
Now, Paul and Scot collect long-term data on the white shark population that feeds for several months of the year in the study area between Tomales Point, the Farallon Islands and Año Nuevo Island north of Santa Cruz. They and other white shark researchers in this study area have published 25 papers and counting.
Scot and Paul believe the population is increasing but still vulnerable. In their study area, they estimate there are 250 to 300 individuals, which they say is not a high number but still represents a healthy population for an apex predator that doesn’t usually exist in large numbers.
A white shark that feeds in Tomales Bay will travel over 1,200 miles in the winter and early spring to an area scientists call the “white shark café,” halfway between Baja California and Hawaii. “We aren’t entirely sure what they do there, but most likely they mate,” Paul said.
To make the journey, sharks need a full store of fat in their livers, which is why they come to the marine mammal-rich shores of the Point Reyes National Seashore and the Greater Farallones National Marine Sanctuary. At this time of year, they are hunting the abundant seals and whales in the area. Feeding is their main concern, and they will come up to the surface to inspect any mass that looks like it could be food, and usually take a preliminary bite.
Last Saturday was preceded by three days of fair weather. Scot and Paul spent two days circling the Farallones and two days at Tomales Point. They encountered 14 sharks, including one predating a dead elephant seal, and six or seven humpback whales. It was the last day they went out together for the season.
Scot killed the engine and motioned to Paul to let lose the anchor roughly a quarter-mile from the tip of Tomales Point, where waves crashed against the cliffs. The water was a dark, dusty blue with a depth visibility of several feet. It swelled every 20 seconds in 10-foot hills as the researchers prepared for their work.
The tools of their trade are simple, and some are hand-rigged: a GoPro camera mounted on a long pole, a water bottle strapped to a wooden stick, a bucket full of marine mammal blubber, a metal meat hook, a machete, a wooden chopping block and a decoy seal at the end of a fishing line.
Scot slung the chopping block over the side of the boat and began to hack at a thick piece of seal blubber, shedding bits of meat into the water and releasing the fatty lipids that attract the sharks. The pair uses salvaged marine mammal bait such as harbor porpoise or elephant seal in small amounts to chum the water—though chumming isn’t the right word, Paul said: “It’s less than that. We never want to feed the sharks. We don’t want to condition them to associate boats with food. It’s important for us not to alter their normal behavior.”
The water bottle on the stick brought water back and forth between the meat bucket and the ocean, and the water around the boat was soon slick with a sheen of fatty oil. Used in tandem with this scent cue was the seal decoy, which was cast behind the boat as a visual cue. The idea is that a shark will smell something it wants to eat, see the shape of something it wants to eat and come up to the surface so the researchers can get a better look.
While they wait, they look for signs such as a “boil,” a disturbance in the water caused by the tail of the shark displacing water and causing ripples. Less than 10 minutes after dropping anchor, Paul spotted a boil several feet from the boat.
When a shark breaches, the moments pass quickly. The head appears as the shark goes for the decoy, but when it realizes there is no meal to be had it dives back down under the waves. But not before Paul dunks the GoPro underwater to catch a video, Scot snaps a photo of the dorsal fin, and they both make mental notes on the size, age and sex of the animal.
The most important information Scot and Paul note are the unique markings on the dorsal fin. When a white shark is born its dorsal fin is smooth, but as it matures the fin grows and cracks along the back edge. The cracks, combined with other unique markings, such as battle or strike wounds or the threads of copepod parasites, create what Paul calls a barcode for the shark. This helps them know if they have encountered the shark before.
With the data they gather, Paul and Scot are trying to paint a full picture of this season’s white shark population. A healthy population is indicative of a healthy ecosystem, but it can be challenging to get a full picture. “They are cryptic,” Scot said of the sharks. “They don’t really like to be seen. They are on the bottom, they are camouflaged, they are looking for opportunities to get a seal. It’s a tricky challenge to study marine animals. There are extra barriers to studying sharks because they don’t need to come up for air.”
The pair says they have the most robust dataset on white sharks in the world, based on the sheer number of hours they spend conducting observations. “In any wild population study, it is a rare occurrence to have data collected on individual animals over a long period of time on the same population and in the same spot,” Paul said.
They share their data with the Tagging of Pacific Predators research collaboration, hoping the information can help establish ecosystem management tactics and stable long-term populations. The group also seeks to apply new technologies to the study of large open-sea animals in the North Pacific.
On their last excursion, Paul and Scot came equipped with an acoustic transmitter but didn’t have the opportunity to place it. The technology is costly and not as fundamental to their research as the identification of dorsal fins. Still, it has helped them discover that white sharks swim all along the West Coast, from Washington State to central Mexico, before heading off to open waters in the winter and early spring.
Paul and Scot tagged one shark this season. They haven’t heard its beacon since, but anticipate its re-emergence next August. “When we put out an acoustic tag, it’s the beginning of a story on how long that animal stays in a place, how often it moves or if it prefers one site over another,” Paul said. “It is interesting to see where they choose to come first after that journey.”
White sharks live 100 years and possibly more, so the only way to get a real estimate of population trends is to engage in long-term study. Before the pandemic, Scot and Paul were funded by the Monterey Bay Aquarium, but when Covid shut the aquarium’s doors, the money allocated to research was cut. “We lost our research boat and our funding—our platform,” Scot said.
According to Paul, the aquarium used to keep young white sharks until they outgrew their enclosures. The popularity of the attraction led the organization to bring the pair on as seasonal researchers.
Now, with their funding gone, the researchers have set up a GoFundMe page, where they post updates on their findings. They have plans to start a new nonprofit that they hope will allow for more permanent funding.
“Right now, we are in survival mode,” Paul said. “We aren’t getting paid in any type of way, but we are hoping to create a sustainable nonprofit very soon.”
To learn more or to contribute, go to www.gofundme.com/f/California-Great-White-Shark-Count.