OAKLAND, Calif. - Two dead whales were found in different parts of the San Francisco Bay Area Friday, leading to speculation as to what might be causing the marine mammals' deaths, CBS SF Bay Area reports. 

A large dead whale washed up Friday in the Oakland Estuary just a few miles downstream from the busy Port Of Oakland container ship hub, officials said. The Marine Mammal Center said the whale was partially submerged near Jack London Square. 

NOAA and the U.S. Army Corps of Engineers were able to tow the carcass out into San Francisco Bay with the plan of taking it to Angel Island State Park so that scientists can perform a necropsy, or animal autopsy, to determine the cause of death.

NOAA officials said they received reports Wednesday that a deceased whale was draped across the bow of a large ship entering the San Francisco Bay and heading to the port. It was not known if the whale was the same animal in the report.

The species, length, age and sex was currently unknown until further examination by marine biologists.

On the Marin County coast, a second whale was found on Tennessee Valley Beach Friday afternoon.

The Marine Mammal Center said it was a 35-foot female gray whale. Marine biologists will also do a necropsy on that whale Saturday to try and determine a cause of death.

The Marine Mammal Center has responded to several other dead whale reports in 2018. The leading causes of death examined by the Center's research team include blunt force trauma from ship strikes, malnutrition, trauma and entanglement.

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