Scientists fear for future of fragile orca species
Fourth southern resident killer whale found dead
To lose a young, pre-reproductive female, is deeply vexing because of all the lost potential. PETER ROSS VANCOUVER AQUARIUM
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 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 life time. To lose her does have a conservation implication.”
There are now 77 individuals 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 calf born in early September is thought to have died a month later. An adult female of breeding age and an adolescent male also died.
“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.”
Among the threatened northern resident killer whales, an adult male and female are also thought to have died this year, leaving an estimated population of 290.
Scientists won’t conduct a necropsy of the latest killer whale carcass on the beach near Comox until today, 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 get 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 from a shortage of their primary prey, chinook salmon, as well as from marine noise and disturbance.
Provincial veterinary pathologist Stephen Raverty will lead the necropsy, with the federal Fisheries department and Vancouver Aquarium experts.
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 coastal waters of Washington state and Canada.
Raverty said he has seen two photos of the stranded orca and also believes it was pregnant.
The population numbered more than 140 animals decades ago but declined to a low of 71 in the 1970s .
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 .
The whale found Thursday was last seen in Puget Sound and photographed on Nov. 26 with her family east of Victoria, according to the 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.