A dead grey whale washed ashore in San Francisco on Monday, the ninth dead whale found in the Bay Area in the last two months.
The Marine Mammal Centre confirmed to NBC Bay Area that it performed a necropsy, or animal autopsy, on the whale on Tuesday.
The necropsy showed that the whale died from blunt force trauma, likely from striking a ship.
The Marine Mammal Centre's research shows that three of the whales it’s found have died as a result of ship strikes, with the most recent whale likely included.
Four others died from malnutrition. The cause of death of the eighth whale washed ashore in the Bay Area is unknown.
Dr Pádraig J Duignan, the chief research pathologist at the Marine Mammal Centre, led the research team during Tuesday’s necropsy. He told CBS that the number of whales dying from malnutrition is due to a lack of food in the Arctic, leaving whales migrating during the fallin bad shape.
“Fifty per cent of the population was judged to be below normal body condition,” Dr Duignan said, explaining that the malnourishment continued from fall into winter. “That’s a lot of time and a lot of energy without any additional food.”
The first two grey whales found dead this year were calves, who are less adept at surviving with little to eat.
Last year, more whales died from being struck by ships off the coast of California than ever before since the National Marine Fisheries Service began tracking ship strikes in 1982.
A local news station says the San Francisco Bay Area normally sees only 1-2 dead whales per year, making this year’s number of deaths alarming.
"The death of nine grey whales in the San Francisco Bay Area this year is a cause for serious concern and reinforces the need to continue to perform and share the results of these type of investigations with key decision-makers," Dr Padraig Duignan, Chief Research Pathologist at The Marine Mammal Centre, said in a statement. "We are committed to partnering with organisations and individuals to find long-term environmental solutions to prevent these deaths in the future."