This year’s local white shark count wrapped up with record highs at the Farallon Islands, puzzling lows at Tomales Point, anomalous observations across the board and the return of a familiar friend—a 16-foot-long shark named Sickle-Fin who has been spotted several times since 2008.
Paul Kanive and Scot Anderson, the president and vice president of the nonprofit California White Shark Project, are happy with their findings. Over a period of 29 days, the pair counted 85 white sharks. Now, while the sharks migrate from the California coastline back into the vast Pacific Ocean, the researchers will analyze and compare their data to that of previous years, identifying sharks they sighted twice and any new ones visiting the area for the first time.
Mr. Anderson and Dr. Kanive have contributed to some of the world’s most important studies on shark behavior and migration. For 36 years, they’ve observed two key areas off the Marin coast—two square miles around Tomales Point and the perimeter of the Farallon Islands—during fall and winter.
Though the year began with a steady influx at Tomales Point, sightings tapered off in October for a season total of only 16 sharks. The number continued a downward trend at the location that began in 2020.
At the Farallones, the researchers spotted 69 sharks—a banner year for the project. Dr. Kanive said the numbers are puzzling, especially as biologists on the islands reported another year of dropping elephant seal numbers. Elephant seals are key prey for white sharks, offering higher caloric value than the more abundant sea lions.
Sharks at Tomales Point tend to be more diverse in age. Juvenile sharks that have recently grown to seven or eight feet long can feast on squids, rays and other small sharks while learning to hunt for wandering pinnipeds. If they are competent enough, they can eventually move to the Farallones, where competition is more intense. Sharks around the islands tend to range in length from 12 to 19 feet. “You have to be big enough and bad ass enough to compete there,” Dr. Kanive said. “The sharks who have been there for decades aren’t too keen on competition, so we see a lot of sharks with wounds.”
Sickle-Fin is one of a few Tomales graduates, Dr. Kanive said. “We’ve been monitoring it for years,” Mr. Anderson said. “We’ve seen it change in size, lose the top of its tail and heal from it. The top third of its fin got taken out and looks like a sickle—hence the name.”
Many sharks display battle scars either from prey or from run-ins with other sharks. The team’s diver, Ron Elliott, has worked with the crew for over a decade to capture up-close shots. “I like being out there with them,” Mr. Elliott said. “Everyone once in a while, things get a little dicey and I get fearful, but it’s something you have to channel.”
White sharks migrate to the coast starting in August to feed until February, when they return to an area between Hawaii and Baja that scientists call the white shark café. Dr. Kanive said it’s unclear what sharks do in the area, but one theory is that they breed. He went on an expedition to the expanse in 2018. “I didn’t see a single shark when I was there,” he said. “It’s a vast area in the open ocean. You feel really small really quickly.”
Dr. Kanive and Mr. Anderson started tagging sharks in the late ‘90s. Their work, undertaken in collaboration with Stanford University’s Hopkins Marine Station, led to the discovery of the white shark café. Until then, experts only had guesses as to where sharks spent half the year.
The tags, attached to sharks’ dorsal fins, record location, temperature, depth and light levels—data that builds a large-scale record of migratory patterns. Researchers rely on low-resolution data before the tags run out of battery and must be retrieved to access higher-resolution data.