Two dead gray whales wash ashore in San Francisco Bay, as experts say one died from malnutrition but are unable to work out what killed the second

  • Two gray whales found floating in San Francisco Bay on Sunday and Monday
  • One of the 23ft female whales were severely malnourished with little body fat 
  • Pathologist Padraig Duignan said the whale hadn't had enough food to migrate

By James Gant For Mailonline

Published: | Updated:

A dead gray whale washed up in a city bay this week after it died from severe malnutrition.

Marine experts said they found a lack of blubber and body fat on the whale in San Francisco Bay on Tuesday and its stomach was empty.

The 23ft female whale was seen floating between Tiburon and Angel Island on Sunday night and it washed up near Belvedere Cove.   

A  gray whale carcass that washed up on a shoreline in San Francisco Bay on Sunday night is examined by experts from The Marine Mammal Center in Sausalito on Tuesday. The Center said on Thursday that the whale had died from severe malnutrition

A  gray whale carcass that washed up on a shoreline in San Francisco Bay on Sunday night is examined by experts from The Marine Mammal Center in Sausalito on Tuesday. The Center said on Thursday that the whale had died from severe malnutrition

Another was spotted by the Army near Bay Bridge on Monday - but tests had to be abandoned on the second due to unsafe conditions. 

The team from Marine Mammal Center in Sausalito conducted necropsies on the one-year-old whales at Angel Island State Park.

Padraig Duignan, the center's chief research pathologist, says it's likely the malnourished whale had not eaten enough over the winter. 

He said: 'It's likely that after not feeding this winter, she didn't have enough reserves built up to survive her journey north.'  

The center have found the number of gray whales entering San Francisco Bay this year has been 'abnormally high.'

It says the animals are staying in the bay much longer than usual during their annual northward migration from Mexico to Alaska.

A second whale washed up on Monday but experts had to abandon their examinations due to unsafe conditions

A second whale washed up on Monday but experts had to abandon their examinations due to unsafe conditions

Experts have also seen a migratory behavior change with gray whales entering the Bay in the late winter and early spring months.  

In the past one or two gray whales have passed under the Golden Gate Bridge during this period.

But last week alone five were counted entering the bay.

Bill Keener, a whale expert at Golden Gate Cetacean Research, told The Mercury News: 'The number of gray whales entering the San Francisco Bay this year has been abnormally high, and they're staying much longer than in years past.' 

He added: 'There's likely a few factors at play here, including food source availability and a relatively sheltered habitat for juvenile whales that are in weaker body condition.' 

Whales commonly die from blunt force trauma - often caused by being hit by a ship.

They can also die from entanglement and infectious disease but there is no evidence of this with these whales.                  

The Marine Mammal Center has seen more than 70 gray whales in distress in its 44-year history.

But this week's incident was the first two whale necropsies they have done this year.

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