By Pamela Cruz. Peninsula 360 Press [P360P]/Bay City News
The death of a gray whale that washed ashore last weekend in San Francisco remains a mystery after experts performed a necropsy on it Monday.
The cetacean's death is the 14th since April, the highest number in the region since an unusual mortality event was declared in 2019, according to the Marin Headlands-based Marine Mammal Center.
Scientists reported Tuesday that they were unable to confirm the cause of death after a necropsy Monday afternoon at Ocean Beach, but they took samples from the whale for testing and that may help experts understand the whale's history.
"Gray whales are sentinels of ocean health, so conducting this research is essential to better understand how human activity and changing environmental trends are affecting this species," said Dr. Padraig Duignan, director of pathology at the Marine Mammal Center, in a statement.
"While the death of this whale remains a mystery, the large number of dead gray whales in the San Francisco Bay Area reinforces the need for us to continue to conduct both live whale watching research and necropsy investigations so that this critical data can be shared with key decision makers," he added.
This Monday, scientists were able to discover that the whale was a 45-foot adult female whose body condition was average based on cape and blubber reserves.
The whale had multiple fractured vertebrae, but no nearby bruising or hemorrhaging, so scientists believe it was struck by a ship after it died due to another cause.
The scientific team discovered very little food in the whale's stomach, and also noted that the whale was heading north towards the food-rich Arctic waters at the end of the season.
An unusual mortality event, declared by the National Oceanic and Atmospheric Administration, has been ongoing since 2019, because higher than usual numbers of gray whales in poor body condition have been coming ashore throughout the species' migratory range, according to the Marine Mammal Center's
Scientists at the center have found that malnutrition, entanglement and ship strikes are the most common reasons dead whales have been found in the Bay Area in recent years.
Other reasons include harmful algal blooms, disease, predators and human interaction.
"Adult females with young are usually the last to migrate north to summer feeding grounds in Alaska. However, this adult female showed no signs of having recently nursed a calf," said Maoe Flannery, senior manager of bird and mammal collections at the California Academy of Sciences, in a statement.
He added that there is hope that samples taken during the necropsy will shed "some light" on the reasons behind their late journey north and any potential ailments that may be affecting the gray whale population.
Arrangements are being made to bury the whale at Ocean Beach, which is part of the Golden Gate National Recreation Area.
