Nigel, the orca scientists called L95, was 20 years old and should have been in the prime of life when he was found dead in Esperanza Inlet, off the west coast of Vancouver Island.
Killer whales live from 50 to 80 years usually, so something went tragically wrong for Nigel, a member of the endangered Southern Resident population, which has been under close watch by whale researchers for decades.
The Department of Fisheries and Oceans recovered the carcass, and an initial necropsy failed to determine a cause of death.
But questions are being asked about the distinctive two-pronged wounds found at the base of the whale's dorsal fin. They were inflicted when scientists with the U.S. Northwest Fisheries Science Center (NFSC) fired a satellite tag on a 5-centimetre dart into Nigel's back on Feb. 23.
He was found dead five weeks later.
For several years, the NFSC has been shooting satellite tags into orcas in an attempt to understand what is troubling the Southern Residents, a population that is down to 83 animals from 98 in 1995. A shortage of Chinook salmon and exposure to toxic pollutants are thought to be the main reasons the whales, which spend much of their time around southern Vancouver Island, are endangered. One fear is that the whales' systems are so polluted a stressful event can push them over the edge.
The necropsy results on Nigel did not point to the satellite tag as a cause. But people are wondering if it was a contributing factor, since the whale died so soon after being tagged.
"I think it is a concern," said Andrew Jones, president of the North Island Marine Mammal Stewardship Association. "These studies, these tags, they definitely have their place. The question is, is this the place for them?"
Peter Hamilton, founding director of Lifeforce, an ecology foundation, said satellite tags should not be used because they can cause wounds that expose the whales to bacterial and viral infections.
Mr. Hamilton has concerns about other scientific research methods, too.
"We think there should be a thorough review of skin biopsies, because it's obvious that shooting a biopsy dart into orcas can also open pathways for very toxic pollution," he said.
Mr. Hamilton said a joint U.S.-Canada committee should be set up to "look at the cumulative effects of all the research that's being done on this one endangered population."
In a statement, the NFSC said that when L95 was tagged, the whale "appeared to be in good health" and there were no apparent problems.
"The deployment was routine in all regards," the NFSC states.
But Nigel stopped transmitting three days later, and when his body was found, the satellite tag was only partly there, suggesting it broke off, perhaps opening a wound.
"We are extremely saddened to learn of L95's death and are working closely with our Canadian counterparts to interpret necropsy findings and understand the cause of death," the NFSC statement said. "The team has halted tagging activities until a full reassessment of the tag design and deployment is completed to reduce risk of this happening again."
Jenny Atkinson, executive director of the Whale Museum in Friday Harbor, Wash., said when the satellite tagging program was proposed in 2010, her non-profit questioned it, saying less invasive research methods could probably provide the information sought.
Ms. Atkinson said that while no link has been established between Nigel's death and the tag fired into his back, she wants to see the detailed, final necropsy report.
"We are pretty frustrated by how long it takes to get results," she said.
DFO has indicated the report will be ready in about a month.
But Ms. Atkinson said she is still waiting to see the final results of a DFO necropsy on Rhapsody, or J32, an 18-year-old pregnant female who was not satellite-tagged that died suddenly near Courtenay, on Vancouver Island, in December, 2014.
She said toxicology reports often get sidelined in busy government labs, but given the endangered status of the Southern Residents, the analyses should be an urgent priority because it could hold clues to what threatens the whole population.
"What's taking so long?" Ms. Atkinson said. "If you have this unique opportunity to do a necropsy on an endangered killer whale … stop everything and get it done."