In the past few weeks, two young gray whales have been found dead in San Francisco Bay, a third was discovered north of Bodega Bay and five have been found dead in Washington state.
Biologists are studying the dead animals to determine if there is anything unusual about their deaths or if they may be linked, but say the number of dead whales isn’t outstandingly high.
“A certain level of whale mortality is normal this time of year,” said Erin Falcone, a biologist at Cascadia Research Network, the nonprofit responsible for responding to whale deaths in Washington. “This has been a relatively high mortality year for us, but it’s not our highest year on record,” she said.
Though the two deaths in San Francisco Bay this year have been high-profile, there actually haven’t been more deaths than usual for the Northern California region so far this year, said Jim Oswald, spokesman for the Marine Mammal Center in Sausalito.
In fact, this year’s mortality figures don’t come close to rivaling the all-time-high mortality reached in the 1999 and 2000. In 1999, some 283 dead whales were found on the Pacific Coast — seven times the mean of 41 reported in the years prior. The following year, that figure rose even further, to 368 carcasses found, according to a study published in 2005 by the National Oceanographic and Atmospheric Administration.
Though there was no conclusion as to what caused the dramatic increase in mortality, one prevailing theory linked the deaths to changes in the ice covering in the Bering and Chukchi seas in Alaska. Another suggested the El Niño year in 1998 could have contributed.
Jackie Dragon, marine sanctuary program director for nonprofit Pacific Environment, said the organization is worried that the high level of shipping traffic and noise through the Bay and the sanctuary outside the Golden Gate results in ships striking and killing whales and young whales becoming disoriented.
The two young whales found dead in the Bay each appeared to be malnourished, but there was no obvious signs of blunt injury by a ship, said Oswald.
The first whale appeared north of Fort Mason on April 20, and its carcass was still intact enough that it could be towed to shore for a necropsy. The second carcass was discovered floating several hundred yards off the Ferry Building on Wednesday, but it was significantly more decomposed. By the evening, it had washed ashore on Angel Island.
Oswald said that biologists were finally able to access the whale on Friday morning and took samples for study, but were not able to immediately determine a cause of death.
Between the two discoveries in the Bay, a third gray whale was discovered dead north of Bodega Bay, and the Marine Mammal Center biologists analyzed that death as well, Oswald said. He did not have information about its age or cause of death.