Climate variability and change is reshaping marine ecosystems faster than we can often observe directly. While satellites and ocean models give us excellent information about physical conditions like temperature, there are far fewer tools for detecting ecological change as it happens. In Heather Welch’s recent paper in PNAS, we explore an unconventional but powerful idea: commercial fishermen themselves can act as ecosystem sentinels. Using Vessel Monitoring System (VMS) data from more than 600 U.S. fishing vessels, we show that the collective movements of fishermen provide accurate, near real-time signals of climate-driven shifts in tuna distribution and availability in the Northeast Pacific.

We find that changes in fishing effort captured by VMS data reliably track extreme northward and inshore shifts of albacore tuna, as well as northward shifts of Pacific bluefin tuna, during marine heatwaves. Remarkably, these behavioral signals often outperformed simple environmental indicators like sea surface temperature anomalies. Because fishermen’s livelihoods depend on finding fish, their decisions integrate complex ecological information such as prey availability, population structure, and ocean conditions that temperature alone cannot capture. VMS data also revealed a sharp drop in albacore availability during the 2023 fishing season, more than a year before a formal federal fishery disaster declaration was requested.

Our results suggest that fisheries data already mandated for compliance and management could be repurposed as a powerful tool for ecological monitoring in a rapidly changing ocean. Near real-time indicators of shifting species distributions and declining availability could help managers anticipate transboundary fishing conflicts, avoid market collapses, and accelerate disaster response for fishing communities. As climate extremes continue to unfold, leveraging the real-time decisions of people who work on the ocean every day may be one of the most effective ways to detect ecological change before its impacts become irreversible.