SAN FRANCISCO—As of Thursday, April 8, four gray whales have washed up on Bay Area shores. Scientists at the Marine Mammal Center & Academy of Sciences have been trying to figure out what the cause of death for these gray whales. 

The experts confirmed the adult female gray whale pictured at Muir Beach in Marin County died to blunt force trauma due to ship strike.

“On average, over the last 10 years 5-10 whales wash up on shore in the Bay Area” said Giancarlo Rulli, a representative of the Marine Mammal Center when speaking to the San Francisco News about the recent spike. “In 2019, there were 13 gray whales that had washed up on shore, in 2020 there were 5 and in 2021 so far there have been 4.”  

When a whale carcass washes up on shore, a necropsy is performed where scientists examine the whale’s blubber fat to see if it is malnourished and to observe the muscle tissue and skeletal structure to see if it suffered any bruising or fractures congruent with a ship strike or entanglement. Ship strike has been confirmed as the cause of death for two of the whales based on necropsy results while the other two require further investigation. 

Necropsy results have taken longer to attain due to the centers priority on human safety due to the pandemic. Smaller teams of scientists have had to respond to the calls thus prolonging the time it takes to complete a necropsy. 

Another determining factor in the amount of whales washing up is their migration patterns. In the months of March-May, gray whales are usually migrating north & south up the coast while ships are going east & west which creates a rise in ship strikes among whales.

“Based on data from previous years we expect to see more whales wash up on shore but we really hope that doesn’t happen,” said Rulli.