An international team of scientists from Australia, Russia, the Philippines, Mexico, the United States, Canada, and other nations has identified a likely driver behind the die-off of roughly 7,000 humpback whales in the North Pacific. The breakthrough came from a long-running, cross-border study conducted over more than two decades, with clear evidence linking the whales’ steep population decline to an extended marine heatwave that stretched from 2012 to 2021.
By pairing cutting-edge artificial intelligence with extensive population data collected over the past twenty years, researchers traced a 20% drop in humpback whale numbers in the region to unusually warm ocean conditions. This climate anomaly disrupted essential feeding grounds and altered the marine ecosystem in ways that hindered the whales’ ability to locate prey and sustain themselves in the North Pacific.
In 2013, sea temperatures surged well above typical levels, with anomalies reaching about 5.6°C above long-term norms. The heat anomaly covered a vast area, estimated at roughly 4 million square kilometers, reshaping the marine food web and shifting the distribution of species that humpback whales rely on for nourishment.
The heatwave persisted for three years, triggering a cascade of ecological changes: recurring toxic algal blooms, shifts in where key fish species could be found, and widespread disruptions to commercial fishing activities. These disturbances compounded stress on the ecosystem and reduced the availability of traditional prey for humpbacks. Cooler conditions did not reemerge across the Northeast Pacific until late 2016, prolonging the period of ecological imbalance and challenging the whales’ foraging success.
As waters continued to warm, humpback whales faced greater difficulty securing enough food. Researchers estimate that the region’s humpback whale population declined from about 33,488 individuals to around 26,662, reflecting the enduring impact of the warming event on reproductive success and survival rates in the North Pacific.
Earlier discussions by scientists had touched on unusual findings at the species level, highlighting how even small physiological or behavioral adaptations could influence responses to shifting prey availability. The present findings emphasize how large-scale environmental fluctuations can produce lasting effects on marine megafauna and stress the importance of long-term monitoring to understand and anticipate such dynamics. Overall, the study shows how technology and cross-disciplinary collaboration illuminate the drivers behind broad ecological changes, offering a clearer picture of how climate-related shifts translate into tangible consequences for a highly migratory population like humpback whales.