At least 13 gray whales have washed up dead in the San Francisco Bay area since January, marking a concerning spike in fatalities for this migratory species, according to preliminary data from the National Oceanic and Atmospheric Administration (NOAA). The deaths represent a 30% increase over the same period in 2023, continuing a pattern of elevated mortality first documented during the 2019-2023 ‘Unusual Mortality Event’ that saw over 600 gray whales perish along North America’s Pacific coast.
Necropsy reports obtained by SourceRated indicate malnutrition as a recurring factor, with several specimens showing depleted fat reserves. ‘These animals should be building energy stores during their northward migration to Arctic feeding grounds,’ said a NOAA marine biologist speaking on background. ‘Instead, we’re seeing emaciated adults and calves – something’s disrupting their food chain.’
The phenomenon coincides with record sea surface temperatures along the California Current System, where gray whales typically feed on amphipods and other benthic organisms. A 2024 UC Davis study published in Marine Ecology Progress Series found warming waters have reduced amphipod biomass by 40% in key feeding areas since 2016.
However, officials caution against monocausal explanations. ‘While climate impacts are a leading hypothesis, we’re also evaluating ship strikes, algal toxins, and disease vectors,’ said a spokesperson for the Marine Mammal Center, which has responded to seven strandings this season. Commercial shipping traffic through the Bay Area increased 18% year-over-year in Q1 2024, per Port of Oakland records.
The die-off raises concerns about the Eastern North Pacific gray whale population, which rebounded from near-extinction to an estimated 27,000 individuals before recent declines. Scientists warn cascading ecological effects could emerge if mortality rates persist, potentially affecting everything from kelp forest ecosystems to Indigenous hunting traditions in the Arctic.