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A dead gray whale floats off\u00a0Cavallo Point in San Francisco Bay on April 3, 2026.<\/p>\n
Norely Faz \u00a9 The Marine Mammal Center, NOAA Permit #26532<\/p>\n
Like many gray whales<\/a>, a young male called Denali likely wintered in the balmy waters off Baja before propelling northward each spring to fill his belly in the Arctic. Marine scientists saw this whale, named after his white spot shaped like Alaska, every year between 2020 and 2024. But last April, partway through his 10,000-mile annual migration, Denali died in San Francisco Bay.<\/p>\n Local scientists from the Marine Mammal Center and California Academy of Sciences, who examined Denali\u2019s body near the Golden Gate Bridge, believe that a vessel probably struck him. In 2025, Denali\u00a0was one of 21 dead gray whales, a record-high number for the Bay Area.<\/p>\n Article continues below this ad<\/p>\n The first research<\/a> to document the fatalities, published in the journal Frontiers in Marine Science on Sunday, found that at least 18% of the gray whales spotted in San Francisco Bay from 2018 to 2025 died. Vessels killed at least 40% of them, and many others starved, the study found.<\/p>\n \u201cThis is a really important study because it sets the stage for researchers to go in and understand, almost in real time, a significant change not only in the behavior of this species but also the negative impacts of human activity,\u201d Ari Friedlaender<\/a>, a UC Santa Cruz ecologist who studies whale<\/a> migrations but was not involved in this research, told\u00a0SFGATE.<\/p>\n The new study documents the gray whales\u2019 plight, but elements of the story remain a mystery. And it\u2019s still happening. In 2026, at least six gray whales have already\u00a0washed up dead<\/a> in the Bay Area, according to the Marine Mammal Center. (Experts from both the center and the California Academy of Sciences contributed to the new study.)<\/p>\n Between 2018, when gray whales started appearing more regularly in San Francisco Bay, and 2025, experts identified 114 of the sea giants visiting, according to the study. Most came for the first time and didn\u2019t return, with only four appearing across multiple years, the authors report. To compile the numbers on the whales\u2019 different fates in the bay, the researchers used local surveys, photographs and necropsy records.\u00a0<\/p>\n Article continues below this ad<\/p>\n \u201cWhile we found a minimum confirmed mortality rate of 18%, we do have a lot of evidence that would support the actual mortality rate likely being higher, even in the range of between 40% and 50%,\u201d Josephine Slaathaug, a graduate student at Sonoma State University and the lead author of the paper, told SFGATE. \u201cThat\u2019s very concerning.\u201d<\/p>\n It\u2019s not just the so-called \u201cbay grays\u201d\u00a0in trouble.<\/p>\n The Eastern North Pacific population of gray whales, which migrates along the West Coast, faces dramatic declines overall. In 2025, this population of grays fell to just shy of 13,000 whales, the lowest<\/a> number recorded since the 1970s. The whales are likely struggling to find enough food<\/a> in the summertime in the Arctic, where climate change is disrupting the ecosystem.<\/p>\n Slaathaug said one theory on why they keep entering the bay is that they\u2019re hungry and looking for food. Malnutrition, leaving the whales weak,\u00a0might even make it easier for vessels to catch them.<\/p>\n Article continues below this ad<\/p>\n<\/p>\n