What may be the largest toxic algae bloom ever recorded on the West Coast is poisoning sea lions in Washington State and shutting down fisheries as far north as B.C.

Although levels of a harmful phytoplankton are much lower in B.C. than off the coasts of California, Oregon and Washington, they are high enough that the Department of Fisheries and Oceans has shuttered shellfish harvesting for some areas of Vancouver Island.

That’s because the algae is producing domoic acid, which is neurotoxic to mammals.

Nicky Haigh, of the Harmful Algae Monitoring Program at Vancouver Island University in Nanaimo, B.C., said the algae can hurt humans when they eat contaminated shellfish.

The algae can also cause skin rashes, sore throats, red eyes and gastrointestinal illness in humans and pets who come in contact with it the water.

Researchers from the University of California, Santa Cruz first detected the bloom of Pseudo-nitzschia in May.

Raphael Kudela, a professor of ocean sciences at UCSC, said that the bloom may be of record size due to unusually warm water.

Earlier this month, the bloom caused Washington State to shut down its crab fishery for the first time since 2003.

With a report from CTV Vancouver