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A whale named TMMC-1-66, also known as \u201cOreo,\u201d is seen swimming in central San Francisco Bay on June 1, 2023.<\/p>\n
Josephine Slaathaug\/The Marine Mammal Center NOAA-NMFS Permit #26532<\/p>\n
A whale named TMMC-1-91, also known as \u201cLadybug,\u201d is seen swimming in central San Francisco Bay against the backdrop of the city skyline on May 5, 2025. This whale later died.<\/p>\n
Josephine Slaathaug\/The Marine Mammal Center NOAA-NMFS Permit #26532<\/p>\n
The carcass of a whale named TMMC-1-91, also known as \u201cLadybug,\u201d washed ashore in a rocky area near\u00a0McNears Beach in San Rafael on May 31, 2025. Many carcasses such as this are inaccessible for a full examination or necropsy due to difficult terrain.<\/p>\n
Adelle Wilkin\/The Marine Mammal Center NOAA-NMFS Permit #26532At least 18% of gray whales entering the San Francisco Bay since 2018 have died, with researchers estimating the true mortality rate could be 50% or more.A significant number of the gray whale deaths in the bay are believed to be caused by vessel strikes, including many adult females.Gray whales are spending longer periods in the bay, with one individual staying up to 75 days before dying.<\/p>\n
As food disappears from their feeding grounds, gray whales are swimming into San Francisco Bay\u00a0\u2014 and many are dying.<\/p>\n
At least 18% of gray whales entering the bay since 2018 have died, according to a research paper published this week in Frontiers in Marine Science. It\u2019s unusual for gray whales to enter the bay during their nearly 12,000-mile round-trip migration from Arctic feeding grounds to breeding areas off the Mexican coast, since they typically fast along the way. But as Arctic waters warm and the whales\u2019 primary prey \u2014 largely crustaceans and other invertebrates \u2014 declines, researchers believe they may be taking an emergency pit stop to feed.<\/p>\n
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Many of the whales are newcomers to the bay\u2019s waters. Scientists believe these whales, called the Bay Grays, may be establishing a new migration pattern, potentially in the search for new feeding grounds. The whales are still trying to recover from a mass die-off from 2019 to 2023 that reduced their population by close to half, driven partly by malnutrition.<\/p>\n
The search for food has brought encounters with deadly obstacles. The study identified 114 whales that entered the bay, but at least 21 of them died between 2018 and 2025. The true toll is likely higher, since many whale carcasses sink or are swept out to sea, and skin decay can make some animals impossible to identify. Josie Slaathaug, the study\u2019s lead researcher, estimated that upwards of 50% entering the bay could have died.<\/p>\n
Only four of the 114 were seen years later in the bay; an unknown number presumably made it back out to the open ocean.<\/p>\n
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<\/p>\n Add Preferred Source<\/p>\n <\/a><\/p>\n \u201cOne of the theories that we have as to why the number isn\u2019t larger of returning individuals is that they have a very high mortality rate,\u201d Slaathaug said.<\/p>\n Article continues below this ad<\/p>\n Boat strikes appear to be a leading cause of death. Among the 21 gray whales reported dead after entering the bay, roughly half are believed to have been mortally struck by ships.<\/p>\n To enter the bay, whales must pass through the Golden Gate Strait, a bottleneck for ship traffic headed to ports in Oakland, San Francisco and Richmond. Ferries, tour boats and recreational boats frequently cross bay waters; on April 5, for example, a ferry from Richmond to San Francisco stopped suddenly, and passengers could see a whale off the side.<\/p>\n Many of the dead whales studied were adult females \u2014 a big concern for a species that is nearing its lowest calf count on record.<\/p>\n \u201cIn any population that\u2019s struggling with rebounding from an unusual mortality event, you really look at the breeding females and how they\u2019re doing,\u201d Slaathaug said. \u201cTo see adult whales and adult females of breeding age dying in the San Francisco Bay Area by vessel strikes is extremely concerning.\u201d<\/p>\n Gray whales are also spending longer stretches inside the bay. In 2023, researchers photographed 17 whales, including one that stayed at least 75 days. By 2025, they observed 36 whales, with the longest stay recorded at 67 days.<\/p>\n Article continues below this ad<\/p>\n The whale who stayed in the bay for 75 days had initially been hit by a boat across its back, breaking bones, suggesting the injury kept it there. It later died after another boat struck it, and the whale hemorrhaged and suffered multiple rib fractures. Slaathaug said that the whale\u2019s mandible was also broken.<\/p>\n Researchers say measures such as speed limits when whales are present or changes to shipping routes could reduce deaths. On April 22, a statewide voluntary speed reduction program will ask shipping companies to slow their vessels to 10 knots or less along the majority of the California coast<\/a>.<\/p>\n \u201cThe slower a vessel goes, you have kind of a trifecta of risk-reducing factors that happen,\u201d Slaathaug said. \u201cYou have more time for the captain to potentially see whales in the area. You have more time for whales to get out of the way and make their own avoidance maneuver, and you also reduce the risk of a lethal strike versus a sub-lethal strike.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"A whale named TMMC-1-66, also known as \u201cOreo,\u201d is seen swimming in central San Francisco Bay on June…\n","protected":false},"author":2,"featured_media":581253,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[51],"tags":[3805,2356,1687,192,5284,79,201],"class_list":["post-581252","post","type-post","status-publish","format-standard","has-post-thumbnail","category-wildlife","tag-bay-area","tag-california","tag-climate","tag-environment","tag-san-francisco","tag-science","tag-wildlife"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/581252","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=581252"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/581252\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/581253"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=581252"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=581252"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=581252"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}