Drakes Estero shark bite was likely investigative

01/18/2018

Just before the attack, there was a lull in the waves. In the calm, she played on her surfboard, kneeling on its face to practice balancing—and then she slipped. The majority of her body was back on her board, out of the water, when she screamed and jerked her feet upwards, kicking away from biting teeth. The shark surfaced then, rising above the water to reveal an eye, a belly, a fin. Then it disappeared.

Natalie Jones, an Oakland resident and former reporter for the Light, suffered bites to both of her feet from a juvenile or subadult—likely 10 to 12 feet long—white shark on Dec. 30 in the waters near Drakes Estero. She was surfing with her boyfriend and another friend and all three paddled to shore immediately following the incident.

The lacerations were serious enough to warrant stitches, which were taken out last week. (Although she provided details for this story, she did not wish to comment further.)

Ralph Collier, founder and C.E.O. of the Shark Research Committee and director of the Global Shark Attack File, is the leading expert on white shark interactions with humans, and is documenting Ms. Jones’s case.

“From her description, it sounds like an investigative incident, rather than a predatory one,” Mr. Collier said. “Predatory attacks are very high-energy—in some cases they fly up out of the water, or hit something very hard with the objective of getting it in their mouths, of killing. But this was a mild, more gentle bite. The shark looked her over at the surface, determined she wasn’t interesting, and swam off.”

The majority of shark attacks—80 to 85 percent—directed at humans are investigative, according to Mr. Collier’s research. In these cases, the shark is exploring its environment and, lacking hands, may use its mouth to examine unfamiliar objects. The remaining attacks are split between “predatory” and “displacement” activities, the latter of which refers to a wide range of behaviors that a shark might demonstrate under circumstances of conflict or stress. 

On the Pacific coast, there have been 103 “unprovoked shark attacks” such as Ms. Jones’s— which Mr. Collier defines as incidents with any physical contact between a shark and a human without provocation or offensive gestures on the part of the human—from 2000 through the end of 2017. There were at least five in that time period in West Marin. Before that, Mr. Collier believes there were just 108 attacks in all of the 20th century. That number is based on extensive research, primarily a combing of the archives of coastal newspapers.  

Mr. Collier attributes the increase in attacks mostly to “population dynamics.” With more humans on earth, there are more people in the water. And, as marine protections over the past two decades have outlawed hunting whites and safeguarded much of their food supply, their numbers have likely risen as well. 

 Mr. Collier said exact numbers of white sharks are unavailable, due to the difficulty of tracking the numbers of any type of fish that disappear into the ocean. Still, he said, sightings have certainly gone up in areas of known habitat.

The white shark has been positively identified, or else is highly suspect, in 88 percent of all of the unprovoked shark attacks on the Pacific coast since 1900. Of the 13 fatalities throughout that history, the species is likely responsible for all of them.

Ms. Jones said that her friend, who was about 30 feet away from her when the shark surfaced, also got a good look at it. He saw its eye and caudal fin, which, unlike a dolphin’s tail, is distinctively large and perpendicular to the water. The friend reported that its behavior appeared to be consistent with that of white sharks, as was its size, though Ms. Jones said she could not say with “100 percent certainty” that the attacker was a shark. 

Mr. Collier is now analyzing photos of the bite marks on her skin and booties and will ultimately make a final estimate of its length. (Back in the ’70s, he developed a method of determining the size of a shark by taking “interspace measurements” between the teeth marks.)

White sharks—or great whites, as they are often called—are three to five feet at birth and typically 11 to 16 feet at maturity, though they may reach as long as 26 feet. Two other species of shark are larger, with basking sharks at 33 to 35 feet and whale sharks at 40 to 45, though both primarily eat plankton. 

Based on relatively recent age and growth studies, white sharks are known to live for at least 70 years.

The largest carnivorous fish, white sharks have around 50 functional teeth at a given time, but up to seven rows of teeth in place behind them at successive stages of development. In a conveyor belt-like fashion, a fresh set of chompers cycles in every 10 to 14 days. 

Electric receptors in their snouts can detect the electric energy that animals emit within a three-foot radius; this is helpful for sensing bat rays or halibut buried below the sand, for example. Juveniles eat fishes, smaller sharks and rays, and adults typically add in seals, sea lions, dolphins, whale blubber, squids, seabirds, turtles, crabs and snails.

Though they have a global distribution, populations of whites are known to breed in southern California where the water is warmer and, as they mature and tolerate colder climates, to move northward to pursue larger prey.

Scot Anderson, an Inverness resident, is a seasonal research scientist for Tagging of Pacific Pelagics project, TOPP, a cooperative project with Stanford University, Hopkins Marine Station and the Monterey Bay Aquarium. He says that white sharks can be found all around West Marin, from Tomales Point to Point Bonita, and tend to hug the rocky shorelines and points. (Debunking a local legend, young whites are unlikely to be in Tomales Bay, he said.)

Mr. Anderson is helping to monitor the movements, survivability and growth rates, among other aspects, of white sharks, with acoustic and satellite tags. The satellite tags monitor long-range movements, though they typically come off after a few months. The acoustic tags correspond with receivers set up at three locations known to attract sharks—Tomales Point, the Farallon Islands and Año Nuevo—and record when an individual is near any of those locations. (Only the receiver at Año Nuevo is currently working, however.)

Born in Tiburon, Mr. Anderson began an obsession with great whites through his experience fishing at a young age. “They are primitive in some ways, but also highly evolved,” he said. “There’s nothing like seeing a big, big fish like that close to shore.”

He said his interest is in uncovering the many mysteries about great whites, and particularly about the females—which tend to disappear into the deep ocean for longer periods than the males do—and the species’ breeding habits and gestation periods.

He spends a lot of time near the three different tagging sites in a skiff with his research partner Sal Jorgensen, from the Monterey Bay Aquarium. They use a decoy to attract the sharks and, once one nears the boat, they snap photos above and below the surface and read signals from small acoustic tags that some sharks wear. They can recognize individuals by the unique marks on their dorsal fins and from beeps the tags transmit. 

“There’s a chance they are around almost any time of year, though the main flux of sharks is mid-August to mid-February,” Mr. Anderson said. “We believe that they then go on a migration, way offshore, to the middle of nowhere. If you a drew a line between the Hawaiian Islands and Baja, it would be somewhere around there.”

Mr. Collier reports that over half of unprovoked attacks on the Pacific Coast occur within the three-month period of August through October.

He said that, in Marin waters, this is likely due to a number of factors, including greater densities of marine mammals around during that time. In Point Reyes, there are five pinniped species for adult sharks to feed on—the harbor seal, the northern fur seal, the California sea lion, the Steller sea lion and the northern elephant seal. Point Reyes has the largest population of harbor seals in California, excluding the Channel Islands, with 20 percent of the state’s harbor seals living or breeding within the seashore’s boundaries. Point Reyes is also one of the few places on the Pacific coast where northern elephant seals may be observed, and a growing number breed at Drakes Beach, the Point Reyes Headlands and South Beach, typically from December through March.

Ms. Jones was bitten at the mouth of Drakes Estero, where the confluence of different water sources helps form the sand bars that make waves that are good for surfing. Drakes Estero, Mr. Anderson said, is indeed a particular hotspot for sharks, since seals and sea lions are riding in and out with the current. 

And, he added, a 14-foot white shark was seen three weeks before, in the same place, by a paddle boarder. Sharks have been seen there in the past; another surfer was attacked there back in October 2004 on the Limantour Beach side of the estero.

“It’s often the case that places where there are good waves are going to be the sharkiest places,” Mr. Collier said. “But what do you do? If I tell a guy, ‘Hey, don’t go to Mavericks but go down the coast a few miles, where there are likely less sharks,’ he’s going to tell me to get lost.”

Mr. Anderson, who surfs himself, says that when he goes into the water, he is constantly looking behind him. “My problem is that I’ve seen too much—I’m ruined for life,” he said.

Mr. Anderson added, “If you’re a surfer in Point Reyes, you’ve already somehow come to terms with the risk, so then it’s about managing the risk. Your chances of an encounter go down when there are more people around. Water quality can have an impact as well. In murkier water, a shark may not see you, but it also might be more likely to mistake you for a seal.”

He suggested surfers leave a first aid kit in their car, or on the beach if it’s a long paddle or walk to it.

Mr. Collier, who has personally talked to almost every victim of a shark encounter—or someone who was involved, in the case of mortalities—since he began his research in 1959, said there’s one commonality that has always sparked his interest. A shocking number of people say that just before the attack, they got an ominous feeling and wanted to get out of the water for a reason they couldn’t explain—but they talked themselves into staying.

Over the years, Mr. Collier has spoken with a number of psychologists and neurologists about the phenomenon, though it has not, to his knowledge, ever been studied.

“If we go back 100,000 years, we weren’t the dominant species on earth and we had innate abilities to help us survive from, let’s say, saber-toothed tigers. And there are probably still things that register with our subconscious, maybe triggered by some stimulus in the environment, like the sudden absence of fish or a ripple in the water, that alert us to the potential of an attack,” he said. “My advice is listen to your feelings.”