Regulators again closed parts of the Dungeness crab fishery off central California this spring, a measure that has become increasingly common in recent years, coinciding with the launch of an AI-powered whale detection network designed to impose new controls on maritime activity in San Francisco Bay.
The new WhaleSpotter system, introduced this week, scans the water around the clock for whale blows and heat signatures up to 2 nautical miles away, alerting mariners in real time to prompt ships to slow down or reroute.
Thomas Hall, director of operations for San Francisco Bay Ferry, stated the system allows for adjustments “way before they get anywhere close” and enables tracking data over time to adjust routes during whale season.
The effort follows a rise in gray whale deaths in the bay, with 21 dead gray whales found in the wider Bay Area last year, marking the highest number in 25 years, according to The Marine Mammal Center.
At least 40% of these deaths were attributed to ship strikes, with at least 10 more dying in the Bay Area so far this year, figures scientists suggest likely underestimate the true toll.
Scientists increasingly link gray whales diverting into San Francisco Bay and lingering for days or weeks to climate change, citing warming temperatures and shifts in sea ice in the Arctic disrupting their food web, as detailed in a 2023 study in Science.
Many whales now concentrate in a high-traffic corridor between Angel Island, Alcatraz, and Treasure Island, directly overlapping with established ferry routes and shipping lanes.
Rachel Rhodes, a project scientist at the Benioff Ocean Science Laboratory, described this area as “the worst place possible in terms of all the ship traffic,” noting that response teams “ran out of places to even land dead whales.”
Despite being removed from the Endangered Species Act 32 years ago after rebounding from commercial whaling, the eastern North Pacific gray whale population has since plummeted by half over the last 10 years, with just 13,000 remaining, according to the National Oceanic and Atmospheric Administration.
Rhodes commented that whales “may not be getting the quality or quantity of food they’re used to in the Arctic,” starting their “incredibly long migration at a disadvantage.”
Technocratic Oversight Expands
The AI system automatically flags potential whale sightings, which are then verified by trained marine mammal observers before alerts are sent by radio to ferry operators and vessel traffic controllers and posted publicly on the Whale Safe website.
While WhaleSpotter systems are used in other nations, researchers stated the San Francisco Bay network is the first to directly integrate land-based and vessel-mounted detections with official mariner alerts, relaying sightings in near real time.
The first hours of testing produced an “immediate flood of detections,” prompting Douglas McCauley, director of the Benioff lab, to admit it “put me a little bit on edge,” adding, “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.”
One camera was installed on Angel Island, with a second soon to be fixed aboard a ferry, creating a “moving data collection platform,” and scientists hope additional cameras on the Golden Gate Bridge and Alcatraz will expand coverage across the bay.
Displacing Native Livelihoods
A severe marine heat wave off the California coast is shrinking the band of cold, nutrient-rich water, causing humpback whales to follow prey closer to shore, where California’s Dungeness crab fishery operates.
This overlap creates entanglement hazards from the tens of thousands of vertical lines connecting traps on the seafloor to surface buoys used by the fishery.
Regulators again closed parts of the fishery off central California to conventional gear this spring, a measure that has become increasingly common in recent years as warming waters increase whale overlap with crab fishing seasons, directly impacting the native working class of fishermen.
Kathi George, director of cetacean conservation biology at The Marine Mammal Center, explained that humpbacks can get lines caught on their bodies, leading to entanglement, and can drag heavy gear for months, resulting in starvation, infection, and drowning.
Thirty-six whales were confirmed entangled off the West Coast in 2024, the highest number in 2 years, though scientists caution most cases go undocumented.
California approved 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 by adopting new technology that stores ropes and buoys on the seafloor.
Caitlynn Birch, Oceana’s Pacific campaign manager, stated that “adaptive and science driven” management will be necessary to reduce wildlife risk and keep fishermen on the water, adding that California has been a “national leader” in developing whale-safe fishing technologies that could guide other fisheries nationally.
Scientists expect the overlap between whales, ships, and fishing gear to persist as climate change reshapes ocean conditions and whale migration patterns, suggesting ongoing justification for these expanding controls.