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During the first week of May, on May 3 and May 4, two gray whales were reported dead in the San Francisco Bay. These two whales, together with one found dead the last week of April, washed ashore in Tiburon, the Port of Oakland and at Angel Island State Park.

On this occasion, experts and scientists from the Marine Mammal Center and their partners at the California Academy of Sciences, have said they may not be able to determine a cause of death due to “inaccessible or unsafe locations as well as shifting tides”. 

They are currently holding discussions with the National Oceanic and Atmospheric Administration (NOAA) to safely tow the whale carcasses into open ocean where they could naturally decompose.

This spring, there has been an increased number of gray whales in the San Francisco Bay as the population migrates to cold, food-rich Arctic waters, and there has also been an alarming increase of whale deaths.

In February, an adult female whale was found dead at North Salmon Creek Beach and the cause of death couldn’t not be determined. By the end of April , the number of dead gray whales increased to six. Three of them, died of suspected ship strike and the three others, had an undetermined cause of dead.

Kathi George, Director of Field Operations and Response at The Marine Mammal Center, has said; 

Over the last few years, our experts have observed gray whales frequenting San Francisco Bay in greater numbers and for longer periods of time.These whales are at increased risk from human activity, which is why we are committed to better understanding the ongoing challenges and threats these animals face so we can safely share the ocean and bay with them.

According to figures by the Marine Mammal Center, a leader in marine mammal health, science and conservation, and the largest marine mammal hospital in the world; 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. 

NOAA has declared an Unusual Mortality Event (UME) for the species and there is an ongoing investigation where the Marine Mammal Center is closely working with NOAA’S gray whale UME team. 

Experts have confirmed that 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. On April 28, the Center for Biological Diversity filed a legal petition asking the federal government to decree mandatory speed limits for ships traveling along parts of northern and southern California in order to reducing collisions with whales.Catherine Kilduff, an attorney at the Center, said at the time; 

Too many whales die from ship strikes off California, and the solution is mandatory speed limits.We know that slowing vessels down gives whales a fighting chance to avoid getting hit. And we know voluntary speed limits just aren’t working. Speed limits make our freeways safer, and they’ll make our shipping lanes safer too. 

Marine mammals are federally protected, and members of the public must not approach any whale, whether alive or dead.

Biologists claim climate change affects water temperatures and prey availability, and this leads to shifting food sources for marine mammal populations and other marine species. Overfishing can also lead to reduced prey availability.