San Francisco deploys artificial intelligence to combat rising whale fatalities from vessel collisions

An artificial intelligence system that scans San Francisco Bay around the clock for whale blows and heat signatures has been activated to alert ships to slow down or change course. The network, called WhaleSpotter, uses thermal cameras and machine learning to detect whales up to two nautical miles away, sending real-time warnings to ferry operators, vessel traffic controllers and the public.

Thomas Hall, director of operations for the San Francisco Bay ferry, said the system would allow mariners to make adjustments “way before they get anywhere close” and would help track where whales are “camping out” so routes can be altered during whale season to avoid those areas entirely.

Why the system was needed: a deadly rise in whale strikes

The launch comes as San Francisco Bay has recorded an alarming rise in gray whale deaths. Last year, 21 dead gray whales were found in the wider Bay Area – the highest number in 25 years, according to the Marine Mammal Center – with at least 40 per cent killed by ship strikes. So far this year the toll has continued: 24 whales were found dead in the wider Bay Area in 2025, 21 of them gray, according to the California Academy of Sciences and the Marine Mammal Center. Of those, eight were confirmed as suspect or probable vessel strikes.

Scientists caution that the true number is likely higher because many carcasses sink or are swept out to sea before they can be counted. Studies suggest a minimum mortality rate of 18 per cent for gray whales entering the bay, with some research estimating the figure could be as high as 40 to 50 per cent.

Gray whales have long migrated along the California coast on their 12,000-mile (19,300km) journey between breeding lagoons in Mexico and feeding grounds in the Arctic. But since 2018, an unprecedented number have been diverting into the crowded estuary and lingering for days or even weeks. Researchers have identified 114 individual gray whales entering the bay between 2018 and 2025, many of them emaciated.

Scientists link the shift to climate change. A 2023 study published in Science found that warming temperatures and changes in sea ice in the Arctic are disrupting the food web gray whales rely on during summer feeding, leaving them malnourished before they even begin their migration. Many are now concentrating in a high-traffic corridor between Angel Island, Alcatraz and Treasure Island – directly overlapping with ferry routes and shipping lanes.

“It’s the worst place possible in terms of all the ship traffic,” said Rachel Rhodes, a project scientist at the Benioff Ocean Science Laboratory who led the initiative. So many whales have been hit that “the teams responding to strandings said they ran out of places to even land dead whales”.

The eastern north Pacific gray whale population, once hailed as a conservation success story after rebounding from commercial whaling and being removed from the Endangered Species Act in 1994, has plummeted by half over the last decade from nearly 27,000 whales in 2015-16 to just 13,000 now – the lowest number recorded since the 1970s, according to the National Oceanic and Atmospheric Administration (NOAA). The population has been hit by two Unusual Mortality Events, the most recent declared from January 2019 to November 2023, associated with Arctic ecosystem changes leading to malnutrition, low birth rates and increased deaths.

How WhaleSpotter works – and how it verifies sightings

The WhaleSpotter system combines advanced AI detection models with visual inputs from highly stabilised infrared thermal cameras. These cameras detect the heat signatures of whales, allowing 24-hour monitoring even in darkness, glare and the thick fog that often shrouds the bay. An AI model analyses the imagery in real time, identifying patterns consistent with whale surfacings. Every detection is reviewed within seconds by trained marine mammal observers, who confirm the sighting before an alert is sent.

The San Francisco Bay network is the first to directly integrate land-based and vessel-mounted detections with official mariner alerts, allowing near-real-time relay of sightings to ships. One camera has been installed on Angel Island and a second is to be placed on a ferry travelling between downtown San Francisco and Vallejo, creating what Rhodes described as a “moving data collection platform”. Scientists hope additional cameras on the Golden Gate Bridge and Alcatraz could eventually expand coverage across the bay.

The first hours of testing produced an immediate flood of detections. “Suddenly to have a full sense of how much whale activity is in this space honestly put me a little bit on edge,” said Douglas McCauley, director of the Benioff Ocean Science Laboratory. “But we’re going to use that data and we’re going to be smart about how we use that space and share it with the whales.”

WhaleSpotter systems are already used on vessels and fixed installations such as lighthouses and coastal towers in the United States, Canada and Australia. But the San Francisco Bay network marks the first time camera detections have been tied directly to official maritime alerts. The initiative is a collaboration between the Benioff Ocean Science Laboratory and the Marine Mammal Center, with support from Marc and Lynne Benioff. A pilot system launched in Santa Barbara in 2020; the San Francisco version went live this week.

Researchers say the system’s biggest advantage is constant monitoring. Unlike human observers, thermal cameras can operate through the night and in many foggy conditions. The system aims to reduce vessel strike risk by more than 90 per cent; studies have shown that slowing ships to 10 knots or less greatly reduces the likelihood of fatal collisions.

Beyond ship strikes: entanglements and ropeless gear

While ship strikes are the immediate focus of WhaleSpotter, whales face another serious threat in the same waters: entanglement in fishing gear. A severe marine heatwave off the California coast is shrinking the band of cold, nutrient-rich water where krill, anchovies and sardines thrive. As offshore waters warm, humpback whales have been increasingly following that prey closer to shore, where California’s Dungeness crab fishery operates with tens of thousands of vertical lines connecting traps on the seafloor to surface buoys.

Humpbacks have been entering San Francisco Bay in unprecedented numbers since 2016, feeding on northern anchovy. The species is listed as endangered and threatened, and is especially vulnerable to entanglement. “Humpbacks are curious and they’ll scratch their backs on the gear,” said Kathi George, director of cetacean conservation biology at the Marine Mammal Center. “If they get a line caught on their body, they’ll breach and they’ll roll and end up entangling themselves.”

Whales can drag heavy gear for months, unable to dive or feed properly, leading to starvation, infection and drowning. Nationally, 95 confirmed large whale entanglement cases were reported in 2024 – a 48 per cent increase from 2023 and above the 17-year average of 71.4, according to NOAA. Off the U.S. West Coast, 36 entangled whales were confirmed in 2024, the highest number since 2018, though scientists caution most cases go undocumented. Humpbacks are the most commonly entangled species, followed by gray whales.

In response, California approved commercial use of ropeless pop-up crab fishing gear for the first time this spring. Instead of floating surface buoys tethered to traps, the system stores ropes and buoys on the seafloor until fishermen return and trigger an acoustic release that brings the gear to the surface. Trials in the Dungeness crab fishery have shown high reliability and success in landing crab while eliminating entanglement hazards. This spring, regulators also closed parts of the fishery off central California to conventional gear – a measure that has become increasingly common as warming waters increase overlap between whales and crab fishing seasons.

“We will have to continue to be adaptive and science driven in terms of our management to reduce wildlife risk and keep fishermen on the water,” said Caitlynn Birch, Oceana’s Pacific campaign manager and a marine scientist. “California has been a national leader in developing whale-safe fishing technologies and we hope that model can help guide other fisheries on the west coast and nationally.”