Anchovies sparkled and seawater sprayed from the crusty maws of gray whales as they burst through the surface, again and again, off the coast near Pacifica, fifteen miles south of San Francisco. Groups of up to six gray whales devoured fish for 28 days straight in June 2022.
This was no ordinary feast. For those who know gray whales, it was odd for a couple of reasons.
First, gray whales are known for being the only baleen whales that primarily feed at the bottom of the ocean, eating krill such as crustaceans, shrimp, and worms. They turn sideways in shallow coastal waters with one fin poking up in a behavior known as “sharking.” Then they rake their bristly, sieve-like comb teeth along the ocean floor to scoop up mouthfuls of invertebrates, sifting them out of the mud with their baleen. And there’s a lot of whale to feed: gray whales can grow to be 40 to 50 feet long — as big as a full-length school bus — and can weigh more than 35 tons. Adult gray whales can hoover up 660 pounds of food per day.
Gray whales also journey farther than other species. Every year, gray whales embark on a 12,000 mile round trip voyage — the longest migration of any mammal. Gray whales often fast through the four months between leaving their summer feeding grounds in the Arctic, journeying to breed and raise calves in Baja California in winter, and coming back again. Researchers and whale watchers typically expect gray whales to cruise past California without stopping for as much as a snack along the way.
So why were whales in Pacifica bucking these norms?
Tim Markowitz, field research coordinator at the Marine Mammal Center, a Sausalito-based nonprofit research and advocacy organization, believes they were adapting to an absence of their usual food sources — a lack likely due in part to climate change.
“These whales are hungry,” says Markowitz.
Arctic sea ice has declined by 40 percent since satellites began recording its coverage in 1978. The loss of permanent ice is disrupting the region’s food chains, and could be why gray whales are searching for eats elsewhere. In the spring, balmy sunshine spurs algae blooms on the underside of Arctic sea ice. But less ice means less surface area for algae to grow. With less algae blooming, less algae drifts down to the frigid mud for tiny shrimp, amphipods and other krill to munch on. Gray whales rely on those krill to bulk up for their epic migrations. A lack of a reliable supply of crunchy crustaceans could be a key reason grays whales have been struggling.
In 2019, 122 gray whales were found dead throughout their West Coast route, prompting the U.S. National Oceanic and Atmospheric Administration (NOAA) to declare an official unusual mortality event for the species. Fourteen gray whale carcasses washed up onto Bay Area shores. Of the eleven whales necropsied, researchers found that six died from malnutrition, one from entanglement, and five from ship strikes.
During those hard times, skinny whales swam into San Francisco Bay and stayed for weeks and even months. Markowitz’s research team saw plumes of mud from gray whales raking up the Bay’s bottom. When scientists investigated dead whales’ bodies, they found many with full bellies, evidence that some, at least, were finding enough to eat off the beaten path. They were apparently in search of new grub —including, perhaps, getting creative and lunging at anchovies instead of plunging for plankton.
Gray whales are part of a larger trend of more cetaceans entering and sticking around longer in San Francisco Bay. It’s tempting to call this a return, but evidence for whales having ever populated the Bay is sparse. Historical reports of sightings are few and far between. Ohlone and other indigenous groups do not seem to have whalebone artifacts, and only one gray whale skeleton has been unearthed from a shellmound (it was dated at 2,500 years old). Whether cetaceans are returning to ancient feeding grounds or are newcomers to the region remains unclear — but living with more whales around might become the new normal. Fin and blue whales make pit stops offshore, and the Bay is now regularly hosting humpback whales, harbor porpoises and bottlenose dolphins. Porpoises and dolphins even use it as a mating ground — scientists have documented the sex lives of porpoises from the Golden Gate Bridge.
But the Bay is incredibly noisy and full of traffic. So why are so many whales willing to become our urban neighbors?
Markowitz believes more cetaceans in the Bay means they are adapting to a rapidly transforming climate, like the gray whales’ unusual feeding behavior in Pacifica. Most gray whales will gorge on Arctic krill and fast past California, but researchers are finding that they are more opportunistic and adaptable than was previously thought. When krill is scarce and whales are hungry on their way north, they can be flexible. This means gray whales may make for telling case studies in a rapidly transforming ocean ecosystem.
Markowitz remembers when it was bizarre to see any whale make its way into the Bay, and those that did were unwell or incredibly lost. He is delighted to witness cetaceans being able to survive and even thrive here.
“There’s a lot to be hopeful about,” Markowitz says. “A lot to celebrate.”
Slowing down for whales
Even if the Bay has become appealing to whales in times of climate crisis, it is far from being cetacean-friendly.
Shipping traffic coming in and out of Oakland, San Francisco and Richmond squeezes through the Golden Gate Strait, right on top of a prime picnic area for gray whales, humpbacks, fin whales, and blue whales. Ship strikes and entanglements pose a major threat. It’s estimated that more than 80 endangered whales are killed every year on the West Coast.
No one wants to see whales get killed or injured from crossing paths with skyscraper-sized container ships, which travel at an average of about 15 knots (17 mph) and can travel at speeds up to about 24 knots (28 mph). An East Coast study showed that when ships slowed down to 10 knots (11.5 mph) or less in areas with lots of whales, deadly collisions with Atlantic right whales decreased by 80 to 90 percent.
“The best way to protect whales is to avoid them and slow vessels down,” says Kathi George, the Marine Mammal Center’s director of field operations and response.
This week a new whale-protection program called Whale Safe was deployed in San Francisco. It’s a collaboration between the Marine Mammal Center and UC Santa Barbara’s Benioff Ocean Science Laboratory, which was funded in part by Marc and Lynne Benioff of Salesforce Inc. Whale Safe aims to prevent ship strikes by combining ship speed data and whale monitoring data and sending real-time updates to ship captains navigating the area as well as researchers and the public.
“If Whale Safe becomes successful in San Francisco, it’s going to be a triple win,” says Doug McCauley, Director of the Benioff Ocean Science Laboratory. “A win for whales, a win for climate, a win for people.”
Whale Safe gathers data from underwater microphones attached to buoys around the Bay, and uses machine learning to distinguish whale sounds from other ocean noise. The artificial intelligence was trained on the calls of endangered fin, blue, and humpback whales. This data is combined with whale sightings and statistical models predicting the presence of blue whales, and translated into a “whale presence rating,” which is emailed to ship captains in the vicinity of a high whale presence rating and displayed on an app in real time so they know when and where to slow down. The San Francisco branch of Whale Safe will monitor the waters off the Bay Area’s coast and along the Golden Gate Strait. Hardware for the San Francisco branch of the project cost several hundred thousand dollars, according to McCauley.
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The program also monitors ship speeds with satellite data to create ship report cards, which rate shipping companies based on how often they slow down to 10 knots when passing through vessel speed reduction zones designed to protect whales. In the Bay, 38 percent of ships are not slowing down in whale zones this week according to Whale Safe data.
Whale Safe was piloted in the Santa Barbara Channel in 2020. Based on the project’s data, NOAA now asks ships to slow down to 12 knots (14 mph) or less when passing through an area in the Channel with a lot of whale activity. NOAA and the U.S. Coast Guard already request that ships weighing more than 300 tons voluntarily slow down to 10 knots (11.5 mph) when they pass through Marine Sanctuaries during peak whale migration season, but they’re not all doing it, according to the data released by the Whale Safe group. This year, nearly 40 percent of ship traffic didn’t slow down to 10 knots in both Santa Barbara and Bay Area vessel speed reduction zones, even with Whale Safe established in Santa Barbara.
Making these voluntary vessel speed reduction areas mandatory would require NOAA to change regulations. That’s something the Cordell Bank National Marine Sanctuary and Greater Farallones National Marine Sanctuary, which covers waters northwest of San Francisco, will be asking the public to weigh in on as part of its 2023 review of the sanctuary’s management plan, according to a representative. In the meantime, Whale Safe will track which ships and shipping companies actually reduce their speed in recommended slow zones, and make that data public.
In Santa Barbara, the whale presence was rated as “high” or “very high” for nearly the entire time the whale zone was active in 2021. Compliance rates in the zone rose from 54 percent in 2020 to 59 percent in 2021, ranging from 22 percent to 93 percent for individual companies. In that time, 11 out of the top 12 shipping companies passing through the Channel improved their Whale Safe report cards — one company improved its compliance by 47 percent. Whale advocates hope public pressure will encourage ships to slow down in San Francisco as well.
The report cards, whale presence ratings and other data are available to the public in real time and will be used to study whale ecology in the long term, according to researchers. Citizen scientists can pitch in by logging their whale sightings on the Whale Alert app.
The technology probably won’t catch many gray whales. Gray whales are stealthy and soft-spoken compared to other cetaceans. They are shy singers, too quiet for underwater microphones to reliably detect. And unlike humpbacks, gray whales seldom perform flashy, splashy maneuvers on the surface, making them even harder to spot in time for a fast-moving ship to avoid when they come up for air. Even so, all cetaceans can benefit when ships slow down.
“The greatest threats to whales are caused by people,” says George. “But we can also be their biggest champions.”