Malnourished Gray Whales Struggling To Make It Back To Arctic
SAN FRANCISCO (CBS SF) -- An alarming number of gray whales are dying along the Northern California coast and in the San Francisco Bay this year, victims of a year without sufficient food levels in their native Arctic waters, a leading marine mammal expert said Tuesday.
Dr. Pádraig J. Duignan, the chief research pathologist at the Marine Mammal Center, was leading a team Tuesday doing a necropsy on an adult gray whale carcass that washed up on San Francisco's Ocean Beach.
It was the ninth gray whale to die in Bay Area waters over the last two months and has biologists concerned that 2019 will eventually rival 1999-2000 when 25 whales died in local waters.
The Center has completed necropsies on eight gray whales so far this year. Three whales died due to ship strikes, and four were due to malnutrition. The cause of death for the eighth whale has not yet been determined.
"It all relates back to their life cycle," said Duignan as he stood near the latest whale carcass. "They are born in Mexico, they migrate to Alaska -- the Bering Sea -- in the summer time. That's when they feed and then they migrate back south. During the migration and while in Mexico, they don't fed. So all their feeding is what is happening on the Arctic."
"Last summer, these whales were not getting enough food in the Arctic," he added. "That is the crux of the problem."
He said studies done on whales in Mexico have come to a stunning conclusion.
"The biologists who studied the migration pattern of the whales noted that when they were migrating south last fall and when they arrived in Mexico at the lagoons, they were already in poor body conditions," he said. "Fifty percent of the population was judged to be below normal body condition."
Their condition has only worsen in the ensuing months.
"Winter then followed, they were not feeding and now they are on the northern migration," he said. "That's a lot of time and a lot of energy without any additional food."
Duignan said a result of the migration of hungry whales has been an increase number of sighting in the San Francisco Bay.
"That's why some appear to be coming into the San Francisco Bay to feed," he said. "That would not be a normal feeding area for them.... Whether they have been successful (at finding food) or not we don't know. This is not where they should be on their northern migration. They're definitely in poor body condition now and way worse than they should be for this time of year"
Tuesday afternoon, scientists announced that the whale that washed ashore at Ocean Beach died from blunt force trauma likely attributable to a ship strike.
The scientists discovered multiple fractures on the animal's skull and upper vertebrae and significant bruising in the surrounding area
consistent with injuries resulting from a collision.
The Marine Mammal Center identified the whale as a 41-foot adult female in the early stages of decomposition.
The fact that some of the whales died from collisions with ships may also be a sign that the sea mammals are moving in closer in a desperate search for something to eat.
Whatever the reason, people who visited the site Tuesday morning seemed convinced that man has a hand in what's happening.
"We…we did this. In some way or another," said San Francisco resident Rossana Li, choking back tears.
When asked if she was concerned with the rise in whale deaths, San Francisco resident Crystal Solow replied, "I'm very worried. I don't know. This just doesn't seem right."
"I believe that the ocean's incredibly strong," said local Rachel Starling. "The thing is, it's difficult to tell how far we can push it. We're definitely kind of pushing it to its limits at this point."
Back in 1999, biologists say half the Pacific gray whales died off for unknown reasons. 25 of those whales washed up dead on Bay Area beaches. Since then, things have improved, with only one or two whales washing up locally each year.
Scientists are wondering if we may be seeing the beginning of another mass die-off.
That leaves one question that will only be answered in time: Is this part of a natural cycle, or has the environment changed so quickly that creatures like the whale at Ocean Beach can no longer survive?
SAN FRANCISCO BAY AREA - 2019 GRAY WHALE NECROPSY RESULTS:
- March 10, 2019: San Francisco Bay; Cause of death: malnutrition
- March 11, 2019: San Francisco Bay; Cause of death: malnutrition
- April 02, 2019: Rodeo; Cause of death: malnutrition
- April 10, 2019: San Mateo; Cause of death: ship strike
- April 13, 2019: Richmond; Cause of death: suspected ship strike
- April 13, 2019: Hercules; Cause of death: malnutrition
- April 16, 2019: Pacifica; Cause of death: ship strike
- April 30, 2019: Point Reyes National Seashore; Cause of death: to be determined
- May 6, 2019: San Francisco (Ocean Beach); Case of death: ship strike
