"A new threat to New England's shellfish industry seems to be establishing itself more firmly, and regulators are trying to stay ahead of potentially deadly blooms of toxic algae that may be driven by climate change.
Thirty years ago, four people died from amnesic shellfish poisoning after eating cultured mussels from Canada's Price Edward Island. The mussels contained domoic acid, a neurotoxin produced by a class of algae called pseudo-nitzschia. The toxin turned up in PEI mussels the next year, but for decades after that wasn't heard from again on the Eastern Seaboard.
Then, in the fall of 2016, toxin-bearing pseudo-nitszchia bloomed off Down East Maine in areas that previously never saw an algae bloom, as well as off Massachusetts and Rhode Island. Regulators in Maine have closed Down East shellfish harvests twice since then.
Now for the first time, a pseudo-nitzschia bloom is plaguing a large swathe of Casco Bay, from south and east of Portland to South Harpswell. Much of Casco Bay has been closed to shellfish harvesting for weeks."