Shark expert spots a great white feeding on gray whale off Point Reyes

Marin County biologist and white shark researcher Scot Anderson makes a habit of going to the beach in the mornings just to gaze out to sea and hopefully catch a glimpse of the creatures that live in and around the waters off the California coast.

On Sunday he caught a rare sight.

Anderson said he was surprised to see a large white shark cruising up on a floating gray whale carcass, which washed ashore later that day at Point Reyes National Seashore.

Once he saw the pale mound of whale — which provided respite to passing Western gulls — he knew a shark could come along. Opportunistic feeders, they’ll often eat deceased whales.

But the birds normally would fly away if a shark came near, and after about 45 minutes, they hadn’t. So he went home and came back later, only to find what he’d been hoping for.

Adult whites “don’t show themselves very often,” Anderson said, noting that those visible near the surface more typically are juveniles feeding on fish. The adults, meanwhile, prefer the blubbery, energy-rich elephant seals, sea lions and other types of seals.

Moreover, most white sharks have left their winter feeding grounds off California by now and have headed into open waters between Baja and Hawaii for the summer. They’ll return around August and September and leave again by February.

But “the thing that’s really unique about this sighting isn’t that it’s the middle of winter, or spring. It’s just really rare to see one and then get a photograph from shore, which is where I took the picture,” he said.

Anderson, vice president of the nonprofit California White Shark Project, has studied the elusive creatures for three and a half decades, identifying and tracking them as part of the larger field of research into their role in a dynamic and changing environment.

He and others use seal-shaped decoys and bait to lure the sharks in close for tagging and identification via unique pigmentation, patterns and scarring.

As an apex predator, positioned at the top of the food chain, white sharks play a key role in maintaining balance in the ocean ecosystem while reflecting its overall health, as well.

So it’s surprising that the first long-term attempt to measure the peak white shark population off central California coast produced a relatively small number: about 300.

Released in 2021, the study, led by Anderson’s research partner, Paul Kanive, was based on observations and data, including photographs and underwater video, collected from 2011 through 2018 from Tomales Point, Southeast Farallon Island and Año Nuevo Island, between San Francisco and Santa Cruz.

Even without prior benchmark population measures, researchers deemed the population stable, with a possible, slight increase, thanks to federal protection for marine mammals, their main prey, and bans on near-shore gill net use. White sharks, though not listed under the Endangered Species Act, also are protected by state and federal law because of their vulnerability to human impacts.

However, there are still reasons for caution. Estimates of the population of reproductive-age females have been lower than expected. While the fish can live up to 70 years, perhaps longer, they do not become sexually mature until they are about 26 years old.

“They’re an iconic species and everything, but they have a relatively small population,” Anderson said, “and when they’re here, they’re protected. But when they leave, there’s no protection at all.”

Declining conditions and fatalities among gray whales that migrate along the West Coast, meanwhile, have raised sufficient concern to prompt the National Oceanic and Atmospheric Administration to declare an Unusual Mortality Event, or UME, in 2019 that continues to this day.

Federal scientists last fall estimated a 38% drop in the number of migrating whales since 2015-16, when the migration peaked at an estimated 26,960 whales.

Last year, about 16,650 were counted.

Scientists believe some of the deaths are from ecological changes and shifting food availability in the Arctic, where the whales feed each summer before swimming some 6,000 miles back south to breeding grounds in Baja.

Many of the whales that don’t survive sink at sea. Others wash ashore, where some are found emaciated, though others are found to have died from injuries resulting from ship strikes and were otherwise healthy.

The National Oceanic and Atmospheric Administration reports 86 whale strandings in California since 2019 as of May 2, though the totals have declined in the past two years. So far this year, there had been five, including one March 23 on Bolinas Beach and one at the San Leandro Marina on April 8. Both were male gray whales, a juvenile and a subadult, believed to have died from ship strikes.

The gray whales now are traveling north, toward the Arctic. But Giancarlo Rulli, a spokesman for the Marine Mammal Center in Sausalito, which is part of the Unusual Mortality Event working group, said more and more gray whales have been coming into San Francisco Bay to linger and feed since the UME was declared.

Ten have been spotted in the Bay since observers with the Marine Mammal Center saw the first one Feb. 8, and Rulli urged anyone fishing, boating or otherwise on the water to give them space and report the sighting to the Marine Mammal Center at marinemammalcenter.org or 415-289-SEAL (7325).

The gray whale Anderson spotted was one of two that came ashore this past weekend on the Marin Coast after feeding in the Bay.

The 39-foot adult male he photographed had been sighted several times beginning Feb. 9, when it appeared to be in good condition, the Marine Mammal Center said.

But it was later seen with a healing scar in the middle of its back indicative of a vessel strike and, even later, April 24, appeared increasingly debilitated, with an abundance of sea lice around the scar.

After a record 75 days or more in the San Francisco Bay, it was found emaciated and dead at Point Reyes with injuries believed to have come from a second collision, according to the team of 11 scientists involved in its necropsy Tuesday.

Jagged injuries on its chin were clearly shark bites, Anderson said.

A second, 37-foot adult male that came ashore on Agate Beach near Bolinas on Saturday, in contrast, appeared robust and healthy, with an “abundant blubber layer,” during its necropsy Monday, performed in collaboration with the San Francisco Academy of Sciences and the National Park Service.

A team of 17 involved in the necropsy found contents in its stomach indicating it had been feeding in the bay, as well, but its cause of death remains undetermined.

Anderson said it wasn’t clear whether the shark he saw was just preparing to leave for open water and the summer gathering place scientists refer to as “the cafe,” or may somehow have been lingering along the whale migration route for the chance at an unsuccessful whale. And there’s really no way to know.

“What you could theorize is they’re still here and it’s getting ready to go,” Anderson said. “I don’t really know how they think. But they definitely know what they’re doing, and it’s all about food, and they know how to find it.”

You can reach Staff Writer Mary Callahan (she/her) at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.