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SAN FRANCISCO, Calif. (AP) — Ferries, cargo ships, and tankers navigated the choppy waters of San Francisco Bay on Tuesday as a whale surfaced nearby,
its spout barely visible against the white caps. An AI-powered detection network launched this week aims to track these whales day and night, preventing potential collisions. The system, known as WhaleSpotter, continuously scans the bay for whale blows and heat signatures up to 2 nautical miles away, alerting mariners to adjust their speed or change course when whales are detected.
“They'll be able to make adjustments way before they get anywhere close,” said Thomas Hall, director of operations for San Francisco Bay Ferry. “It will also allow us to track data over time and see where the whales are camping out so we can adjust our routes during whale season to avoid those areas completely.”This initiative arises amid a concerning increase in gray whale fatalities in the bay. Last year, 21 dead gray whales were discovered in the broader Bay Area, marking the highest count in 25 years, according to The Marine Mammal Center, with at least 40% of these deaths attributed to ship strikes. As of this year, at least 10 additional gray whales have perished in the Bay Area.
Scientists suggest that these statistics may underreport the actual impact, as many whale carcasses either sink or are swept back out to sea before they can be located or reported.
Gray whales have historically migrated along the California coast on their approximately 12,000-mile journey between breeding lagoons in Mexico and feeding grounds in the Arctic. However, increasing numbers are now diverting into San Francisco Bay, lingering for days or even weeks in the congested estuary—a trend scientists increasingly associate with climate change. Warming temperatures and changes in Arctic sea ice disrupt the food web that gray whales depend on during their summer feeding months, according to a 2023 study published in Science, resulting in many whales starting their migrations in a malnourished state.
Many whales are now gathering in a high-traffic corridor between Angel Island, Alcatraz, and Treasure Island, overlapping directly 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 spearheaded the initiative. The frequency of collisions has been so high 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 considered a conservation success story after rebounding from commercial whaling and being removed from the Endangered Species Act in 1994, has seen a dramatic decline, with numbers halving over the past decade, according to the National Oceanic and Atmospheric Administration. Currently, only about 13,000 remain.
“They may not be getting the quality or quantity of food they’re used to in the Arctic,” Rhodes noted. “That means they’re starting this incredibly long migration at a disadvantage.”
The WhaleSpotter system utilizes thermal cameras that provide real-time alerts to mariners. Artificial intelligence automatically flags potential whale sightings, which are then verified by trained marine mammal observers before alerts are sent via radio to ferry operators, vessel traffic controllers, and are publicly posted on the Whale Safe website.
WhaleSpotter systems are already operational on vessels and fixed installations such as lighthouses and coastal towers in the United States, Canada, and Australia. However, researchers assert that the San Francisco Bay network is the first to directly integrate land-based and vessel-mounted detections with official mariner alerts, enabling whale sightings to be communicated in near real-time to ships navigating the bay.
Initial testing of the system generated a significant number 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,” stated Douglas McCauley, director of the Benioff lab. “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.”
The system’s continuous monitoring capability is a major advantage. Unlike human observers, thermal cameras can operate during the night and in many foggy conditions that are typical in the bay.
One camera has been installed on Angel Island, and a second will soon be placed aboard a ferry traveling between downtown San Francisco and Vallejo, creating what Rhodes describes as a “moving data collection platform.” Researchers hope to expand coverage across the bay with additional cameras on the Golden Gate Bridge and Alcatraz.
Warming ocean temperatures are also impacting humpback whales. A severe marine heatwave off the California coast is reducing the area of cold, nutrient-rich water where krill, anchovies, and sardines thrive. As offshore waters heat up, humpback whales increasingly follow their prey closer to shore, where California’s Dungeness crab fishery operates.
The fishery utilizes thousands of vertical lines connecting traps on the seafloor to surface buoys, creating entanglement risks for whales migrating and feeding along the coast. This spring, regulators again closed parts of the fishery off central California to conventional gear, a measure that has become more common in recent years as warming waters increase whale overlap with crab fishing seasons.
While gray whales face risks, humpbacks are particularly vulnerable. “Humpbacks are curious and they’ll scratch their backs on the gear,” explained 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 extended periods, hindering their ability to dive or feed properly, leading to starvation, infection, and drowning. In 2024, 36 whales were confirmed entangled off the West Coast—the highest number since 2018, according to NOAA—though scientists caution that most cases remain undocumented.
California approved the commercial use of ropeless pop-up crab fishing gear for the first time this spring, allowing fishermen to continue harvesting through the end of the season. Instead of floating surface buoys tethered to traps, this system stores ropes and buoys on the seafloor until fishermen return and trigger an acoustic release that brings the gear to the surface.
Supporters argue that this technology allows fishermen to continue crab harvesting while significantly reducing the risk to whales. As climate change continues to alter ocean conditions and whale migration patterns, scientists anticipate that the overlap between whales, ships, and fishing gear will remain a persistent issue.
“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.”
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Follow Annika Hammerschlag on Instagram: @ahammergram.
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