Blunt Force Trauma Injuries Due to Ship Strike Likely Cause of Death for Humpback Whale in Half Moon Bay

Scientists at The Marine Mammal Center, the world’s largest marine mammal hospital, suspect the humpback whale that washed ashore Sunday at Manhattan Beach in Half Moon Bay died due to injuries consistent with a ship strike. 

A team of experts from the Center and partners at the California Academy of Sciences performed a necropsy, or animal autopsy, on the dead whale to determine its cause of death. The Center is committed to partnering with organizations and individuals to provide data and find solutions to prevent these deaths in the future.

“This humpback whale had an extensive contusion over her right chest area, a fractured first cervical vertebra and its skull was dislocated from the spinal column,” says Dr. Pádraig Duignan, Director of Pathology at The Marine Mammal Center. “These findings, combined with overall excellent body condition, strongly implicates blunt force trauma associated with a ship strike as this whale’s cause of death.”

During Monday’s necropsy, scientists identified the humpback whale as a 49-foot adult female that was in a moderate stage of internal decomposition based on the quality of the skin, internal tissues and organs. The team also noted the whale had ample blubber and fat reserves.

While the findings of this whale necropsy are tragic, the information gathered from these whales is shared directly with the Center’s partners and helps inform policy decisions that can protect habitat areas, change shipping lane speeds that intersect migration routes and allow experts to better understand shifting food sources for marine mammals in a warming ocean.

The public can play an important role in the conservation of whales by reporting sightings to the Center’s website. To report a dead whale or whale in distress, call the Center’s rescue hotline at 415-289-SEAL (7325). All marine mammals are federally protected, and the public should not approach any whale, alive or dead.

Humpback whales frequent the California coast to feed during the summer and fall months before migrating south to their winter calving and mating grounds off the coast of Mexico.

The Center’s researchers also study the locations and behaviors of whales in San Francisco Bay so that informed decisions can be made to better protect whales. Public funding and support for this investigatory work is essential.

Scientists from The Marine Mammal Center and the California Academy of Sciences were able to collect a series of samples during the necropsy for ongoing research projects. Typically, the California Academy of Sciences archives various parts of each specimen (baleen, pelvic bones, blubber, muscle, etc.) in their scientific research collection and makes them available to scientists from around the world.

The dead whale was first reported to The Marine Mammal Center’s response hotline by beachgoers on Sunday afternoon around 3pm. Due to the tide cycle this week, the team of scientists had a limited window to conduct the investigation safely at low tide. The Center received advance permission from the city of Half Moon Bay and California State Parks prior to conducting the necropsy.

For more information or to set up an interview on this topic, please contact us at media@tmmc.org.

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