Gray whales have been spotted in San Francisco Bay, and it's not a safe place for them. Experts are baffled by the unprecedented number of whales veering off the usual route.
(Photo: Wikimedia Commons/Carlos Valenzuela)
Gray Whales Spotted Swimming Under the Golden Gate Bridge
The gray whales are putting themselves at risk by changing their routes and swimming at San Francisco Bay. Marine scientists have confirmed that at least 71 different gray whales, and possibly as many as 84, swam into the bay between 2018 and 2023. Some whales stayed for over two months, increasing their risk of being struck by cargo ships, oil tankers, or other large vessels.
The whales were identified through thousands of photographs that showed their unique markings on their backs. Only one or two enormous marine mammals visited the bay annually between 2010 and 2017. However, there were at least 16 in the previous year and at least 21 in the following year.
According to Bill Keener, a biologist with The Marine Mammal Center, a non-profit group in Sausalito, one potential reason whales stay in the bay is the lack of food. They are probably weak and need to rest, or they might be trying to find another food source.
Additionally, it might indicate stress among the general public. The pattern appears in the context of a sharp decline in gray whale populations along the Pacific Coast in recent years.
Staying in the bay is unsafe for the gray whales because there's a lot of ship traffic. According to the experts, gray whale carcasses have been discovered in San Francisco Bay off Angel Island, in the vicinity of Richmond, Rodeo, Hercules, San Leandro, Mountain View, the Port of Oakland, Tiburon, the Berkeley Marina, and Martinez during the previous four years.
Around 22 gray whales were discovered dead in or close to San Francisco Bay between 2019 and 2023, according to information from government organizations, the California Academy of Sciences, and The Marine Mammal Center. Of them, 14 passed away from unidentified causes. Necropsies, or investigations on whales, were conducted on nine of the animals by researchers. Six perished from starvation. A collision with a ship claimed the lives of three.
Scientists concluded that the 2018-2023 die-off, which NOAA dubbed an "unusual mortality event," was probably caused by a food scarcity in the Arctic connected to variations in sea ice concentration, wind patterns, and other variables. Whales consume up to three thousand pounds of food per day, with a preference for amphipods, little crustaceans resembling shrimp, worms, and other microscopic animals that dig up from the ocean floor.
ALSO READ: Mysterious Mass Die-Off of 2,000 Gray Whales in Pacific Coast Since 1980 Finally Explained
Where Do Gray Whales Live
Gray whales were formerly widespread in the Northern Hemisphere, but they are now restricted to the North Pacific Ocean, where two populations remain: one in the eastern North Pacific and one in the western North Pacific.
The term "devil fish" was given to gray whales due to their hostile responses when harpooned. Along the west coast of North America, they are the main attraction for ecotourism and whale watching. They are also renowned for their curiosity about boats in particular areas.
Gray whales have one of the largest yearly migrations of all mammals, covering up to 14,000 miles in some instances and roughly 10,000 miles round-trip. While migrating, they are threatened by collisions with other ships, getting tangled in fishing gear, and other disturbances.
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