Scientists with the Marine Mammal Center said Wednesday that the gray whale that washed up on the Rodeo shoreline in unincorporated Contra Costa County last week died of severe malnutrition, but due to decomposition they've been unable to pinpoint its underlying cause.
The carcass was first observed floating near the Carquinez Bridge on April 2, but the following day it washed up on shore and scientists were quick to point out the concerning nature of the discovery, given that two other gray whale carcasses had been discovered in March.
"This animal is representative of a growing issue for migrating gray whales who appear unable to sustain themselves due to shifting food source availability," the center's chief research pathologist Padraig Duignan said in a news release.
The 40-foot whale was an adult male, and center staff said he should have been a skilled forager, but the animal's death may be related to changes in the ocean's food web. They found very little blubber or body fat on the carcass, as well as very little content in its stomach and intestinal tract.
Investigators checked for signs of infectious disease or blunt-force trauma associated with a ship strike, which is a common cause of death for whales in the region, but found no evidence of either.
"The death of a third gray whale in San Francisco Bay this year is a cause for serious concern as it speaks to the broader challenges this species continues to face in its ocean home," Duignan said.
Climate change can impact water temperatures and the availability of prey species, as can overfishing, and effective environmental policies are crucial for the protection of vulnerable marine mammal populations, according to center staff.