Scientists fear for future of southern resident killer whales after fourth death this year


A member of B.C.’s endangered southern resident killer whale population has been found dead of unknown causes in the Strait of Georgia.
Photograph by: George Bates , Bates Beach Oceanfront Resort

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" The death of a fourth southern resident killer whale this year — this time, an 18-year-old female just entering breeding age — has dealt a crippling blow to the future of the iconic, yet highly endangered species in the Salish Sea.

"To lose a southern resident killer whale from an endangered population is very disappointing," Peter Ross, director of the ocean pollution research program at the Vancouver Aquarium, said in an interview Friday. "To lose a young, pre-reproductive female, is deeply vexing because of all the lost potential. She could have delivered five or six healthy bouncing baby whales over her lifetime. To lose her does have a conservation implication."

There are now 77 individuals left in the southern resident killer whale population, including about 28 females of reproductive age, Ross said. Females become reproductively mature at age 15 to 17 and can continue to have a calf every 3.5 to five years into their early- to mid-40s.

A whale born in early September was recently presumed dead. Two additional whales were confirmed missing and presumed dead earlier this year.

"It's pretty alarming that we haven't had a successful birth in three years," Ross added of the southern residents. "All these signs underscore the incredible vulnerability of this very small population."

He said all levels of society must redouble their efforts to do what's necessary to help save the population. "There's a conversation to be had with every one of us seven million people in the Salish Sea."

Scientists won't conduct a necropsy of the killer whale on the beach near Comox until Saturday, but already suspect her death was related to pregnancy.

A former federal fisheries scientist, Ross conducted research in 2000 showing the southern resident killer whales "were among the most PCB-contaminated marine mammals in the world."

He said he hopes to receive tissue samples from this latest whale for testing for chemicals, which may not have killed the whale directly but could have contributed to a diminished immune system, increased susceptibility to disease, and "made the animal a little bit weaker in the face of adversity."

Whales are also thought to be suffering a shortage of their primary prey, chinook salmon, as well as marine noise and disturbance.

Provincial veterinary pathologist Stephen Raverty will lead the necropsy, with the federal fisheries department and Vancouver Aquarium.

The 18-year-old female that washed ashore Thursday was a member of the J-pod, one of three families of southern resident killer whales that spend time in the inland waters of Washington state and Canada.

Ken Balcomb, a senior scientist with the Center for Whale Research, also plans to travel to B.C. to assist in the necropsy to determine the cause of death.

From photo observations, he said, the whale's "belly looks low and extended, and it could be that the fetus died in utero."

Raverty said he has seen two photos of the stranded orca and also believes it was pregnant.

"Based on historical information and clinical observations, the whale's death may have arisen from pregnancy or complications of birth," Raverty said.

The population numbered more than 140 animals decades ago but declined to a low of 71 in the 1970s when dozens of the mammals were captured to be displayed at marine parks and aquariums.

Scientists will exam the organs and take tissue samples of the whale found dead on Vancouver Island. Along with determining its cause of death, they're interested in tracking diseases and other issues to understand health implications for the entire population.

Individual whales are identified by slight variations in the shape of their dorsal fins and distinctive whitish-grey patch of pigment behind the fins, called a saddle patch.

The whale found Thursday was last seen in Puget Sound in late November and last photographed on Nov. 26 with her family east of Victoria, according to Orca Network.

"We cannot express how tragic this loss is for this struggling, precariously small, family of resident orcas of the Salish Sea," the group said in a statement."