Domoic acid suspected in whale deaths

BY ERIC LINDBERG
DAILY SOUND STAFF WRITER

A ship strike killed the blue whale spotted last week floating dead in the Santa Barbara Channel, officials confirmed, making it the third time a blue whale has been hit and killed by a ship in Southern California waters this month.
Scientists believe domoic acid poisoning may be playing a role in the recent deaths, but tissue sample analysis will not confirm that theory for at least two weeks, officials from the Santa Barbara Museum of Natural History said. However, sonar testing by the Navy off the coast of San Clemente Island has been all but ruled out as a potential cause.

“We’re looking into the possibility that something else is going on to make them more susceptible to ship strikes,” said Michelle Berman, the museum’s assistant curator.
Berman explained that whales may be inadvertently swallowing domoic acid — a neurotoxin created by algae blooms — as they gulp up huge quantities of krill, tiny shrimp-like crustaceans that serve as their primary food source.
“It is possible that if the whales are in fact ingesting domoic acid, it may make them sick and disoriented and unable to get out of the way of ships,” Berman said.
Blooms of the naturally occurring algae — known scientifically as Pseudo-nitzschia — are generally seen in the spring, Berman said, but could also be wind-driven.
“Anytime you have nutrient-mixing, you’re going to have blooms,” she said, adding that in certain areas, blooms might be related to human activity, but mostly result from natural nutrient upwellings.
National Oceanic and Atmospheric Administration officials declared an Unusual Mortality Event (UME) in April after determining that domoic acid-related deaths are occurring more often than normal for the region, also naming Berman as the coordinator of the UME investigation. In addition to the UME, museum officials cited the fact that the three recent blue whale deaths have all involved subadult whales, which also suggests domoic acid poisoning.
“The smaller the marine life is, the less of an ability they have to process all of these toxins,” Easter Moorman, the museum’s marketing director, explained. “If there is an increase of domoic acid in these whales from eating the krill, it’s likely that the adults are also being affected but they are handling it better.”
Since domoic acid is water soluble and not fat soluble, Berman said the toxin passes through the body and will be present in stomach contents, urine, feces and possibly blood.
“It’s something that generally doesn’t have long-term effects,” Berman said, explaining that if blue whales ingested the toxin and managed to avoid being hit by a ship, “they would probably be okay.”
However, domoic acid poisoning has been responsible for several human deaths and both permanent and transitory illness in more than a hundred people, often through the consumption of shellfish, according to the NOAA website.
Seals and sea lions are also highly susceptible to the neurotoxin, becoming lethargic, disoriented and experiencing seizures that sometimes result in death. The Marine Mammal Center diagnosed the first case of domoic acid toxicity on the West Coast during the summer of 1998. Since then, hundreds of seals and sea lions have been stranded along California’s coast, filling rescue centers to capacity, according to the nonprofit’s website.
Although blue whales are believed to experience lesser symptoms, the resulting impairment could be sufficient to prevent a whale from avoiding a ship, Berman said. After performing a necropsy on the latest blue whale carcass, scientists determined it had been killed by a direct blow to the skull.
“I think it was a head strike, because the cranium was crushed,” Moorman said.
Extensive damage to the skeleton was further evidenced by broken ribs falling out during the necropsy, she said. Discolored bones and uneven breaks indicated the whale was alive at the point of impact, and dark stains in muscle and tissue suggested an instant death.
After scientists completed the necropsy at Point Mugu Family Beach, the carcass was towed back out into the current and released. Museum officials said due to the extent of the excavation of the whale, it is anticipated the carcass will fill with water and sink.
On September 8, a dead blue whale was discovered in Long Beach Harbor and is believed to have been pushed into port on the bow of a cargo ship. Six days later, on September 14, a ship broadsided another whale along its back, crushing its spine, that carcass eventually beaching in Ventura.
“These are major ships that are hitting them,” Berman said. “...It’s like a train. They can’t stop, they can’t turn. I suspect that they don’t even know they hit the whale.”
Despite widespread speculation, Berman said sonar testing is not causing the whale deaths. San Clemente Island is so far from the Channel, it would be largely diffused and diluted before reaching any whales in local waters, she said. Also, the Navy is using mid-frequency sonar, which is not in the hearing range of baleen whales.
“Thirdly, we look at the ear bones to see any indication of sonar damage and there was none,” Berman said.
She commended the Navy for allowing scientists to complete the latest necropsy at the Point Mugu Air Station.
“It’s a big deal to allow us to bring the animal there and do the whole workup there,” Berman said. “We really appreciate the Navy’s cooperation.”
Earlier this month, about 100 blue whales were reported in the Santa Barbara Channel and that large amounts of krill were prevalent in shipping lanes. Whales haven’t been a common site in local waters during the past few years, but have been spotted with greater frequency this summer, possibly due to richer food sources.
Although there is the possibility of a widespread, contagious illness among blue whales that may be affecting their ability to navigate, Berman said it is not as likely as domoic acid poisoning.
“We’ve never really experienced a major contagion illness in baleen whales,” she said.
Test results for samples form the latest blue whale carcass are being analyzed at a National Ocean Service laboratory in Charleston, S.C., and could take anywhere from two to four weeks.
NOAA officials are asking boaters throughout Southern California to call the Santa Barbara Museum of Natural History if they spot a floating whale by calling 805-682-4711, extension 157.