Post Mortem For Dead Whale In San Francisco Bay

SAN LEANDRO, CA — A dead juvenile gray whale found washed ashore near San Leandro Marina Park was killed by a ship strike a necropsy performed by scientists from the California Academy of Sciences and their collaborators at The Marine Mammal Center shows.

In the necropsy, or animal autopsy, conducted Saturday, April 8, a small team of scientists identified several areas of hemorrhage found in the soft tissue around the male whale’s eye, lower jaw, and shoulder indicating blunt force trauma that occurred while the whale was alive, a news release emailed to Patch by California Academy of Sciences said.

"In addition, they noted severed tail flukes and propeller lacerations along the body of the whale consistent with vessel collision," the release said.

Scientists also found a fishing line encircling the whale's snout, which based on the tissues surrounding the line suggests the whale was entangled while alive.

“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. “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.”

Marine Mammal Center representative Giancarlo Rulli said the Marine Mammal Center was alerted to the dead whale Friday, April 7 and a team from the California Academy of Sciences was sent to perform the necropsy.

"This was a California Academy of Sciences led investigation with us because they had more capacity than us in terms of team members on Saturday," Rulli said, adding that it was important for the team to get there and perform the necropsy as quickly as possible.

"It is that tissue really tells the story," Rulli said explaining that while the average person can see what could be construed as indications of a ship strike, that may not actually be the cause of the mammal's death.

"You can have what appears to the outside viewer that a whale may have been struck by a vessel, but if that whale is already dead and floating at the top of the surface, that's not the cause of death," he explained. "S0 that is why getting out there while the tissue is still fresh is key because it is in the tissue that you can see whether there was internal bleeding which is a key indicator that yes, the whale died as a result of a vessel strike."

Second whale stranding in two weeks

The whale is the second stranding in the Bay Area to be reported this year, the Marine Mammal Center said. The first, a dead gray whale found on Bolinas Beach in Marin County on March 25, died as a result of blunt force trauma from a vessel strike.

The two whales are part of an ongoing increase in whale strandings over the past several years that led to NOAA Fisheries' to declare an unusual mortality event, or UME.

The increase in whale strandings all up and down the West Coast according to information obtained by Patch and first reported on in the Sept. 1, 2022, article "Beloved Whale 'Fran' Killed Off Coast Near Half Moon Bay," has been ongoing since 2019.

“Under the Marine Mammal Protection Act, an unusual mortality event is defined as ‘a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response,’” Justin Greenman, NOAA’s assistant stranding network coordinator for the West Coast Region, explained during a September 2022 interview.

According to Greenman the normal average is one to two strandings a year.

With the discovery of the gray whale in San Leandro bringing the 2023 strandings up to two in the San Francisco Bay Area, the UME is likely to continue, officials said.

NOAA is reporting 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 2015-2016.

UME likely to be ongoing

"It's early and I think that is key. The migration is just getting underway. We have several months to go here," Rulli said Monday, April 10.

According to NOAA Fisheries, to date this year, six whales have stranded on the West Coast of the United States, the two in California, three in Oregon and one in Washington State.

In 2022, a total of 47 whales stranded on the West Coast of the United States with a total of 105 stranded whales along the entire western seaboard including the United States, Mexico and Canada with most coming from the warmer waters of Mexico where whales migrate to breed and bear their calves.

To investigate the UME, NOAA said it has assembled an “independent team of scientists to coordinate with the Working Group on Marine Mammal Unusual Mortality Events to review the data collected, sample stranded whales, consider possible causal linkages between the mortality event and recent ocean and ecosystem perturbations and determine the next steps” for the investigation.

“While the cause of many UMEs is unknown, the investigation aims to determine the cause of all UMEs, when possible,” NOAA said.

According to researcher John Calambokidis, only 5 percent of whale mortalities are documented on the beach.

“I've been disappointed that now, more than 10 years later, we're still, at this voluntary level, when we know that those speed restrictions are what it would take to reduce legality,” Calambokidis said. “Recent surveys we've done indicated there's a major concentration of feeding humpbacks right now in one of the most heavily used shipping lanes coming and going from San Francisco and it seems like it would be an ideal case where something like mandatory speed restrictions would help.”

How boaters can help

Experts aren’t the only ones who can make a difference when it comes to helping the whales during the UME as they migrate between Alaska to feed and Mexico’s Baja peninsula to breed, Greenman said.

“During the UME we have been seeing more whales closer to shore,” he said. “So the public can help us by being responsible boaters and fishers by giving the animals space. If a dead whale is seen folks can report it to our West Coast Region Stranding Hotline: 1-866-767-6114. If an entangled whale is seen, they can report it to 877-SOS-WHALE.”

Boaters can also contact the U.S. Coast Guard on VHF Channel 16.

When finding a stranded mammal, remember all are federally protected by the Marine Mammal Protection Act. Only local and state officials and people authorized by NOAA Fisheries may legally handle live and dead marine mammals so don’t approach or touch injured or dead marine mammals.

The general public can also visit Pay.gov to donate to the Marine Mammal UME Contingency Fund for the current or other UMEs and help cover costs incurred by the Marine Mammal Stranding Network.

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