The Canadian government has closed oyster farming at seven diverse locations in southern B.C. waters, and several other commercial growers have voluntarily stopped selling amidst the worst norovirus outbreak to ever hit the industry.

To date, a total of 304 illnesses have been reported in B.C., Alberta, and Ontario from eating raw or undercooked oysters from the West Coast, said Darlene Winterburn, executive director of the Comox-based B.C. Shellfish Growers’ Association.

While human sewage is considered the most likely source of the outbreak, officials cannot identify the cause, Winterburn said. “Some (of the oyster farms) are in remote areas and some are not. We can’t point our finger and say, ‘Oh, it was this septic system, or there is a break in a line.’ Everybody is scratching their heads and everybody is looking.”

The industry and various government agencies meet weekly to discuss the problem. The unusually inclement winter is also being considered, she said, noting that there have been oyster closures in the Comox area over the years during heavy rains when pollutants flow off the land and into the ocean.

Winterburn said in an interview she doesn’t know the exact number of growers who have voluntarily stopped shipping to market, but speculated it “could be more than 10.” She added: “Nobody wants to make people sick.”