An alarmingly large algae bloom that’s been poisoning wildlife along the U.S. coast has extended all the way up to Vancouver Island.

U.S. scientists have recorded some of the highest concentrations of domoic acid, a deadly natural toxin produced by algae, they’ve ever seen along the coast from California to Washington.

“This is unprecedented in terms of the extent and magnitude of this harmful algal bloom,” Vera Trainer of the Northwest Fisheries Science Center in Seattle said in a statement.

The result is that sardines, anchovies and other fish that feed on algae have been accumulating the toxin, then passing it on to birds and marine life that feed on them.

The same toxin has been found off the west coast of Vancouver Island, putting local fisheries on high alert.

“It’s definitely of concern,” said Nicky Haigh of the Harmful Algae Monitoring Program. “We just don’t know what’s going on in the long-term with these blooms.”

Canada’s Department of Fisheries and Oceans said so far, the bloom isn’t as toxic in B.C. as it is south of the border – but the levels detected were still high enough to force the closure of some shellfish harvests.

It’s unclear what’s caused the massive bloom, which is different from the algae growth commonly referred to as red tide, but recent unseasonably warm weather is believed to be a factor.

Researchers said they will be monitoring the algae closely, and that the next month will be crucial in determining how dangerous the phenomenon could be for B.C. waters.

With a report from CTV Vancouver’s Mi-Jung Lee