Biologist and salmon activist Alexandra Morton is still waiting to receive reports that show what caused a Vancouver Island salmon farm die-off earlier this summer.

Morton visited Greig Seafood's salmon pens in Nootka Sound late July to investigate local rumours of a large die-off at the farm. When she arrived, she was confronted by dead fish and a wrenching stench.

Morton said she searched first for evidence of algae bloom, a natural event known as red tide that sometimes lead to massive marine die-offs, especially during the warm summer. But the water was clear, indicating to her that whatever was causing death among the fish, it wasn't toxic algae.

In a letter addressed to Morten Vike, CEO of Norwegian-owned Grieg Seafood, a multinational company that produces upwards of 20,000 tonnes of Atlantic salmon in British Columbia each year, Morton urged him to make details about the incident publicly available. The letter was subsequently posted on her blog.

"I'm not accusing Grieg of anything," Morton said. "I'm just saying their social licence is on the line here because they’re in public water. If they want us to believe nothing is going on, we need to see some evidence."

Speaking to IntraFish, an international outlet for news and analysis for the global seafood, fisheries and aquaculture industries, Vike called Morton’s allegations "utter nonsense." What Morton had seen was the aftermath of a seasonal algae bloom, he said.

It was the same explanation provided by Stewart Hawthorn, Grieg Seafood's B.C. managing director, who oversees operations of the company's 21 fish farms in the province.

"We get these plankton blooms every year, and while it certainly is a bit unusual to see such mortality, everything is back to normal now," he said, adding the bloom occurred mid-July. "I can categorically say that there's absolutely no disease in these fish."

Hawthorn said about 40,000 fish were killed by the bloom, amounting to nearly seven per cent of the total number of salmon raised on two farms. He would not put a price on the loss, but said the company usually expects that up to 10 per cent of the farmed fish will die in the period between when they are placed in the pens and harvest time.

Hawthorn stressed that samples from the dying salmon had been sent to labs in B.C. and the U.S., and all were cleared of any signs of pathogens.

"Morton is an activist who's got an agenda, and this is clearly part of that agenda," he said.

The biologist sees things differently, calling her investigation an "act of science."

"I went there, I observed, and I reported those observations," she said.

Hawthorn's reassurances that the salmon were cleared of pathogens are not good enough for her. "If they actually have reports from different labs, then let's see them."

Morton reiterated that request in a second letter to Vike and today, after receiving no reply, she addressed a letter to Grieg Seafood owner Per Grieg. She has yet to receive a reply from either.

Kristian Secher is completing a practicum with The Tyee with a focus on marine science and policy issues. Find his previous Tyee stories here.