Summary and body
Ferries, cargo ships and tankers have been cutting through choppy waters in San Francisco Bay with a new layer of sensing intended to spot whales before vessels come too close. The AI-powered network, called WhaleSpotter, launched this week to track whales day and night and provide alerts to mariners to slow down or reroute when whales are nearby.
The system is designed to detect whale blows and heat signatures at distances up to 2 nautical miles, according to the project behind it. WhaleSpotter then automatically flags potential sightings; trained marine mammal observers verify those detections before alerts are sent to ferry operators, vessel traffic controllers, and the Whale Safe website.
Thomas Hall, director of operations for San Francisco Bay Ferry, said the new warning timing will give crews more time to avoid collisions. “They’ll be able to make adjustments way before they get anywhere close,” Hall said, adding that the system would also generate data over time to help adjust routes during whale season to avoid areas where whales linger.
The effort comes as officials and researchers say ship strikes have become an increasingly serious problem for gray whales in the bay. The Marine Mammal Center reported that last year, 21 dead gray whales were found in the wider Bay Area, the highest number in 25 years, and that at least 40% were killed by ship strikes. The same report said at least 10 more gray whales have died in the Bay Area so far this year.
Scientists say the true toll may be higher than the carcass counts suggest because many whale bodies sink or are swept back out to sea before they are found or reported. They also said the pattern differs from how gray whales have long behaved along the California coast, where they typically migrate on their journey of roughly 12,000 miles between breeding lagoons in Mexico and Arctic feeding grounds.
Instead of passing through offshore waters, more gray whales are now diverting into San Francisco Bay and lingering for days or weeks, researchers said. The initiative’s project scientist Rachel Rhodes said the concentration has overlapped with a high-traffic corridor between Angel Island, Alcatraz and Treasure Island, where ferry routes and shipping lanes run close together. “It’s the worst place possible in terms of all the ship traffic,” Rhodes said, adding that stranding response teams had run out of places to even land dead whales.
Rhodes and others said the biggest advantage of WhaleSpotter is continuous monitoring, including during fog and at night when human observers may have limitations. The network uses fixed and moving platforms: one camera was installed on Angel Island, and a second is planned to be fixed aboard a ferry running between downtown San Francisco and Vallejo to create what Rhodes described as a “moving data collection platform.” Researchers said additional cameras on the Golden Gate Bridge and Alcatraz could expand coverage across the bay.
The project team said early testing quickly produced a flood of detections, prompting some initial concern among staff. Douglas McCauley, director of the Benioff lab, said that seeing the first wave of activity left him “a little bit on edge,” while also arguing that the data would be used to manage whale risk and share it with the animals.
In a broader context, the reporting also pointed to climate-driven changes affecting other whale species along California’s coast. A severe marine heat wave has been shrinking the band of cold, nutrient-rich water that supports prey such as krill, anchovies and sardines, researchers said, pushing humpback whales to follow prey closer to shore. That shift increases overlap with California’s Dungeness crab fishery, which uses vertical gear that creates entanglement hazards for whales migrating and feeding along the coast.
The Marine Mammal Center’s Kathi George said humpbacks may interact with the fishing gear, including by scratching and then getting a line caught on their bodies. “Humpbacks are curious and they’ll scratch their backs on the gear,” George said. She said that if a whale becomes entangled, it can breach, roll and end up entangling itself further, and the whale can drag heavy gear for months, leading to outcomes such as starvation, infection and drowning.
Regulators have increasingly closed parts of the fishery with conventional gear as warming waters increase whale overlap, and in spring California approved commercial use of ropeless pop-up crab fishing gear for the first time. The reporting said the ropeless system stores ropes and buoys on the seafloor until fishermen trigger an acoustic release to bring the gear to the surface, and supporters said it reduces risk while allowing harvesting through the end of the season. Oceana’s Caitlynn Birch said California has developed whale-safe fishing technologies and that the state’s approach could guide other fisheries as scientists expect the overlap between whales, ships and gear to persist.