After weeks of tests, scientists from the Santa Barbara Museum of Natural History announced that ships are to blame for the recent deaths of three blue whales in Southern California waters.
Following the results of two necropsies, the museum’s team reported that domoic acid poisoning did not play a role in the deaths of three blue whales found off the Southern California coast. The museum headed the investigation into the deaths of two of the three dead whales, both of which were found in Ventura and Santa Barbara counties. Analysts have since determined that all three whales were struck by vessels in the water.
Museum spokeswoman Easter Moorman said the museum’s team explored domoic acid poisoning as a possible explanation for the large numbers of collisions in such a short period of time.
Plankton produce domoic acid during warm months, usually from March to June. According to Moorman, the levels of domoic acid move up the food chain from plankton to larger marine mammals, which is potentially fatal. Previous researchers have documented the effects of domoic acid in dolphins and sea lions. The museum’s domoic acid tests are among the first conducted on whales.
“It is a neurotoxin,” Moorman said. “It potentially could play a role. With high enough levels, it could impact orientation of whales feeding in the shipping channels.”
National Oceanic and Atmospheric Administration Biologist Joe Cordaro said neither of the levels of domoic acid in the whales were significant.
Cordaro said he is uncertain as to whether the rate of whale deaths is increasing. He said it was possible that communities were just reporting the incidents more frequently.
“We have no way of knowing if there’s something going on different this year, or if this is the norm and we’re just finding out,” Cordaro said.
Moorman said the first dead whale was spotted in Long Beach Harbor on Sept. 8.
“It came into the harbor on the bow of the ship,” Moorman said. “It is a male, and the team down there took skin samples.”
Cordaro said the second dead whale was spotted floating in the Santa Barbara Channel on Sept. 14 and was eventually stranded on Hobson County Beach.
“That whale was also confirmed to have died of a ship strike,” Moorman said. “When we necropsied, the vertebrae was basically cut in half. When the vertebrae was broken, it also severed a major vein and the whale bled out.”
On Sept. 21, the third whale was seen floating near oil rigs, according to Cordaro. It was towed to Point Mugu as part of a joint effort of the museum, the NOAA and the U.S. Navy. Following a second necropsy performed by the museum’s team, the whale’s death was also attributed to a ship strike.
“Unfortunately, some of them are feeding right in the shipping lane,” Cordaro said. “That’s why we believe we’ve gotten so many ship strikes. It’s like a train wreck – big animals in a small area so busy feeding that they aren’t aware of the vessels.”
No ships have reported hitting a whale, but Cordaro said it is possible for a large ship to remain unaware of a collision. Ships that report an incident are exempt from consequences, but if a strike is traced back to a vessel that did not report the collision, the ship could receive penalties.
According to the museum’s Web site, the last known stranding of a blue whale was in Aug. 1996. The frequency of these recent blue whale deaths is a concern for experts.
The NOAA has requested that the coast guard restrict vessel speed to 10 knots in the shipping lanes in order to minimize the force of potential collisions between ships and blue whales. In addition, the agency has asked that any ships that have struck a whale report the incident immediately.