A new whale detection network has been launched in San Francisco Bay, utilising artificial intelligence to monitor the waterway around the clock and alert mariners to the presence of whales in real time. The system, named WhaleSpotter, is designed to track whales day and night by scanning for their blows and heat signatures up to two nautical miles away. When whales are detected, alerts are sent to ferry operators, vessel traffic controllers, and are posted publicly on the Whale Safe website, allowing ships to slow down or reroute before approaching the animals.
Rising Whale Deaths Prompt Action
The initiative comes in response to a sharp increase in gray whale deaths in the bay. Last year, 21 dead gray whales were discovered in the wider Bay Area, the highest number in 25 years, according to The Marine Mammal Center. At least 40% of those deaths were attributed to ship strikes. So far this year, at least ten more gray whales have died in the region. Scientists believe these figures underestimate the true toll, as many carcasses sink or are swept out to sea before being found.
Gray whales have long migrated along the California coast, travelling roughly 12,000 miles 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 inside the crowded estuary. A 2023 study published in Science links this shift to climate change, which is disrupting the Arctic food web and leaving many whales malnourished during migration.
High-Traffic Corridor Poses Danger
Many whales are now concentrating in a high-traffic corridor between Angel Island, Alcatraz, and Treasure Island, directly overlapping with ferry routes and shipping lanes. Rachel Rhodes, a project scientist at the Benioff Ocean Science Laboratory who led the initiative, described this area as the worst possible location in terms of ship traffic. The number of collisions has been so high that response teams have reportedly run out of places to 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 since declined by half over the last decade. Only 13,000 remain, according to the National Oceanic and Atmospheric Administration. Rhodes noted that the whales may not be getting the quality or quantity of food they need in the Arctic, leaving them at a disadvantage for their long migration.
How WhaleSpotter Works
The WhaleSpotter system uses thermal cameras to provide constant monitoring, operating through the night and in foggy conditions common in the bay. Artificial intelligence automatically flags potential whale sightings, which are then verified by trained marine mammal observers before alerts are sent. One camera has been installed on Angel Island, and a second will soon be mounted on a ferry travelling between downtown San Francisco and Vallejo, creating what Rhodes described as a moving data collection platform. Researchers hope to add cameras on the Golden Gate Bridge and Alcatraz to expand coverage across the bay.
WhaleSpotter systems are already in use on vessels and fixed installations in the United States, Canada, and Australia. However, researchers say the San Francisco Bay network is the first to directly integrate land-based and vessel-mounted detections with official mariner alerts, allowing whale sightings to be relayed in near-real time.
Initial Testing Yields Immediate Results
During the first hours of testing, the system produced a flood of detections, surprising even the researchers. Douglas McCauley, director of the Benioff lab, admitted that gaining a full sense of how much whale activity is in the area put him on edge, but he emphasised that the data will be used to manage the space wisely and share it with the whales.
Threats from Warming Oceans and Fishing Gear
Warming oceans are also threatening humpback whales. A severe marine heat wave off the California coast is shrinking the band of cold, nutrient-rich water where krill, anchovies, and sardines thrive. As offshore waters warm, humpbacks are increasingly following their prey closer to shore, where California's Dungeness crab fishery operates. The fishery uses tens of thousands of vertical lines connecting traps to surface buoys, creating entanglement hazards for whales.
This spring, regulators again closed parts of the fishery off central California to conventional gear, a measure that has become increasingly common as warming waters increase whale overlap with crab fishing seasons. While gray whales are also at risk, humpbacks are most vulnerable due to their curious nature, which leads them to scratch their backs on the gear, often becoming entangled. Whales can drag heavy gear for months, unable 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 go undocumented. California approved commercial use of ropeless pop-up crab fishing gear for the first time this spring, which allows fishermen to continue harvesting while dramatically reducing the risk to whales. Instead of floating surface buoys, the system stores ropes and buoys on the seafloor until fishermen trigger an acoustic release.
Caitlynn Birch, Oceana's Pacific campaign manager and a marine scientist, stated that as climate change reshapes ocean conditions, the overlap between whales, ships, and fishing gear will persist. She called for adaptive, science-driven management to reduce wildlife risk while keeping fishermen on the water, noting that California has been a national leader in developing whale-safe fishing technologies.
