Veterinarians for the Vancouver Aquarium are pondering whether human activity might be responsible for the curious death of an ailing wild porpoise rescued from a British Columbia beach.
A team of doctors, volunteers and the coast guard carried out a dramatic, sophisticated effort to save the sea mammal in late April when it washed ashore on Salt Spring Island, between Vancouver Island and the mainland.
Despite intense, 24-hour medical treatment for 18 days, the animal named Siyay died early Sunday.
Preliminary necropsy results revealed the porpoise was likely killed by a build-up of water on the brain, vet Martin Haulena said Monday as he stood next to the outdoor tank where the creature had been on life-support.
While the condition could be congenital, Mr. Haulena and other scientists examining it suspect the cause is a microorganism called sarcocystis, which is usually associated with land animals such as the opossum.
"How did (the porpoise) get introduced to that parasite? Is it run-off from agriculture? Is it the way we treat sewage?" Mr. Haulena asked, noting the finding was quite a surprise.
He said there's lately been increased scientific reports of germs linked with the terrestrial world being found in the sea.
"Is it because now we're finally just getting the facilities and the time and rehab centres that collect these animals and take the time to investigate why they died?" he asked.
"Or is it because there's something changing? Those are really important things we want to investigate."
The condition that killed the harbour porpoise has never been seen before by Mr. Haulena or the pathologist at the provincial animal health centre in Abbotsford, B.C., where it was sent for the post-mortem. The centre has examined between 200 to 300 dead porpoises in recent years.
However, the parasite that causes the water on the brain has turned up in B.C. porpoises before.
When Siyay was being treated at the Marine Mammal Rescue Centre in Vancouver, the team knew the porpoise was emaciated and said it appeared to be suffering from a lungworm-type disease, gastric ulcers and parasites.
Mr. Haulena said only an MRI would have revealed the brain condition. While that option was available, the animal was too fragile to undergo the procedure.
"So it was no surprise that we couldn't pick up on that and I guess in the end no surprise why he did pass away eventually," Mr. Haulena said.
When the two to three-year-old animal was first transported to his care on April 26, Mr. Haulena gave it a 10 per cent chance of survival. He said medicated fish and fluids helped it stabilize over the first week, but it made no progress in week two and took a turn for the worse about seven days ago.
When the creature stopped breathing about 5 a.m. Sunday, staff members performed resuscitation with a hand bag, injected drugs and tried to restart its heart. The efforts failed.
"This animal represents a bigger loss for us because of the intensity, because this is a slightly rarer species, because of that close interaction people had to have with him," Mr. Haulena said.
"It was a really, really cool animal that was struggling to survive. ... It's hard to deal with, hard to take, but everyone tried their best."
Harbour porpoises are a common species along the B.C. coast, though they're considered timid creatures that aren't spotted as frequently as other sea mammals. A handful of the dead animals have been beached along Vancouver Island and the Gulf Islands over the past month, which Mr. Haulena said isn't unusual for spring and late summer.
It was the fact that Siyay washed up alive that made its case so rare.
Siyay is an aboriginal word for friendship. It is also the name of the hovercraft that brought the porpoise to Vancouver.