SAUSALITO (CBS SF) — Three more gray whales have been found dead in San Francisco Bay in the 10 days – including two this week – adding to a growing total of whale deaths in the Bay Area this year.

The three whale carcasses are in areas that unaccessible for scientists to determine the cause of death either because of unsafe locations or shifting tides, according to the Marine Mammal Center, although tissue samples have been retrieved.

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One of the whales washed ashore April 27 in Keil Cove in Tiburon later drifted to Lime Point in the Golden Gate National Recreation Area. The Marine Mammal Center said the whale had been observed while it was still alive, noting it spent 47 days exploring San Francisco Bay and was underweight.

A gray whale carcass at Angel Island State Park. (Marine Mammal Center)

On Monday, a gray whale carcass was spotted at the Port of Oakland where it has apparently become wedged among pier pilings. On Tuesday, a third gray whale washed ashore at Angel Island State Park.

There have now been nine whale deaths in the Bay Area in 2021, according to the Marine Mammal Center. In 2019, from March through May, scientists investigated 13 dead gray whales in the San Francisco Bay Area. In 2020, the Center responded to five dead gray whales in the same time period.

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Malnutrition, entanglement and trauma from ship strikes have been the most common causes of death in whales studied by the Center’s research team in recent years.

It’s believed scientists will not likely be able to determine a cause of death for the most recent three dead whales.

The Marine Mammal Center said researchers have observed increased numbers of gray whales in the San Francisco Bay this spring as the population continues their northerly migration to cool, food-rich Arctic waters.

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Boaters and people on the water were urged to keep a safe distance from whales and report sightings to the Center’s hotline at 415-289-SEAL(7325). All marine mammals are federally protected, and the public should not approach any whale, alive or dead.