Scientists have determined a vessel strike caused the death of a juvenile male gray whale that washed ashore earlier this month near the San Leandro Marina.
On April 8, a team from the California Academy of Sciences and their collaborators at the Marine Mammal Center performed an autopsy, which found that the whale’s blunt-force trauma injuries were consistent with a vessel collision. They also found fishing line encircling the whale’s snout that indicated the whale was entangled while alive, according to a news release issued Tuesday by the academy.
“This specific gray whale incident puts into perspective the added challenges that human activity poses for a species that has lost nearly 40 percent of its population since 2019,” Dr. Jeff Boehm, chief external relations officer at the Marine Mammal Center, said in the announcement. “Public funding, public awareness, and stakeholder collaboration, like that ongoing with the commercial vessel operators, is essential so we can find solutions to help protect whales.”
The death marks the second death of a gray whale in the Bay Area in a two-week span. On March 25, a sub-adult male gray whale washed ashore near Bolinas.
Scientists suspect it also died from a vessel strike.
“(I)t’s more important than ever that we respond to strandings such as the one … to learn as much as we can about the threats these animals are facing and collect crucial data that can help inform science-driven solutions.”Moe Flannery, California Academy of Sciences
The species has in recent years been experiencing an elevated number of strandings along the West Coast of North America, said Moe Flannery, senior collections manager of ornithology and mammalogy at the California Academy of Sciences.
“Since 2019, gray whales from Baja California to Alaska have been undergoing what’s known as an Unusual Mortality Event or UME,” Flannery said in the announcement. “This means it’s more important than ever that we respond to strandings such as the one that occurred this past week to learn as much as we can about the threats these animals are facing and collect crucial data that can help inform science-driven solutions.”
According to the National Oceanic and Atmospheric Administration, which officially declared the UME in early 2019, the number of gray whales migrating along the West Coast has dropped 38 percent to an estimated 16,650 whales since the last population assessment in 2015-16.
In recent years, malnutrition, entanglement and trauma from vessel strikes are the most common causes of death in whales identified by the academy and the center.