Fifth whale found dead in waters of San Francisco Bay within a month

USA Today

23-04-2025

Fifth whale found dead in waters of San Francisco Bay within a month The death comes weeks after a rare minke whale was discovered in the bay and later euthanized.
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Whale remains wash up at San Francisco's Crissy Field
The remains of a gray whale spotted in Northern California on Friday are those of a whale that was initially spotted dead last week, officials say.
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Another dead whale was discovered in the waters of the San Francisco Bay, the fifth creature found in the area in less than a month, officials said.
The female gray whale drifted overnight on April 20 and was spotted by the U.S. Coast Guard near the USS Hornet Museum in Alameda, California, the next day, Giancarlo Rulli, a spokesperson for the Marin County, California-based Marine Mammal Center, told USA TODAY.
The whale marks the fourth dead gray whale and fifth whale overall to wash up in the San Francisco Bay this year, according to the Mammal Center and the California Academy of Sciences. The latest whale death also comes about two weeks after a rare minke whale was discovered in the bay and later euthanized, officials said.
The minke whale was found offshore near the city of Emeryville on April 7 in poor health, with skin peeling and a reddish hue across its back due to severe sunburn. It also struggled to breathe as it tried to navigate the waters, the Mammal Center said. It was euthanized on April 8.
'A difficult decision': Rare minke whale euthanized in San Francisco after being stranded
Necropsies show that two of the three gray whales discovered before the latest deaths were in good condition, but one whale had six fractured vertebrae, likely due to being struck by a passing vessel. The fourth dead gray whale was privately towed on April 22 to Angel Island State Park, where a necropsy will be performed, Nulli said.
Meanwhile, officials are still looking into other causes for the other whales' deaths, including malnutrition, according to Rulli. The previous gray whale strandings in the bay this year occurred between March 30 and April 4.
"While the number of gray whale strandings has surpassed last year's totals in the Bay Area, they are in line with what we saw at the tail end of the mortality event in 2022 and 2023 at this point in the year," Rulli said.
More: 29-foot-long humpback whale found dead on South Carolina 'met some trauma' before death
Whale deaths are occurring during a large migration season
Between March and May, gray whales migrate from Mexico, where they breed and give birth, up north through the San Francisco Bay. They eventually make their way to Alaska and parts of the Arctic, where they go to feed, officials said. Prior to 2018, whales typically avoided going through busy waters in the bay, as they put their lives at greater risk sharing the water with passing ferries, tankers and other large ships.
But in recent years, officials have observed that "some are passing through to stay for a couple of days, some are staying for a couple of months. Some of them have good body condition, some do not," said Rulli. He added that gray whales "are still in a proverbial rut from losing 40% plus of their population" between 2019 and 2023.
The gray whale population was around 19,260 in the latest count during the 2023-24 winter season, Michael Milstein, a public affairs officer for the National Oceanic and Atmospheric Administration's (NOAA) West Coast Regional Office, told USA TODAY on April 22.
"We will have an updated count soon from this past winter, but it is still a few weeks away," Milstein said. "We expect, based on information from the lagoons in Mexico, where many spend the winter, that the updated count will be lower."
Milstein added that the gray whale population has varied within the past 10 years from as many as 27,000 during the 2015-16 winter season to about 14,500 in 2022-23. Gray whales travel more than 10,000 miles round-trip every year, one of the longest wildlife migrations, Milstein added.
"In recent years, we have seen several gray whales enter the Bay each year, perhaps looking for a breather from their migration as a place to temporarily rest or feed. Some of them may die in the Bay, especially if they had not consumed enough food in their Arctic feeding grounds during the previous summer," Milstein said.
"That can leave them without enough energy to complete the full round-trip. That was certainly the case during the unusual mortality event from 2018 to 2023, which brought increased strandings of gray whales" he added.
That so-called "unusual mortality event" involved 690 gray whale strandings, including 347 in the United States, 316 in Mexico, and 27 in Canada, NOAA reported. A joint investigation with NOAA and other agencies concluded the preliminary cause of the event was due to "localized ecosystem changes in the whale's Subarctic and Arctic feeding areas that led to changes in food, malnutrition, decreased birth rates and increased mortality."