Four dead grey whales have washed ashore on San Francisco Bay area beaches in nine days, with experts announcing two of the giant aquatic mammals died from ship strikes and an investigation is ongoing on the other two.
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Biologists with the non-profit Marine Mammal Center in California said two dead whales washed ashore in the Bay area on Thursday, joining two more that were discovered dead in area beaches since March 31.
Of the four animals, two died from blunt force trauma from ship strikes, the centre said in a statement on Saturday.
"It's alarming to respond to four dead grey whales in just over a week because it really puts into perspective the current challenges faced by this species," Padraig Duignan, director of pathology at the centre said in a news release.
Other common causes of grey whale deaths include starvation and complications from becoming entangled in deep sea fishing lines nets and other equipment.
The center's experts were joined by biologists from the California Academy of Sciences to perform the necropsies.
Climate change can affect water temperatures which impacts on the availability of food for the whales, which can grow to nearly 50 feet long and migrate about 16,000 kilometres every year between feeding grounds in the cold, north Pacific waters and breeding grounds in warm-water lagoons of Mexico's Baja California Peninsula.
The species is not currently considered endangered but is protected by the Marine Mammal Protection Act in the United States.
Australian Associated Press
