Following the detections of two aquatic animal diseases, multinucleate sphere unknown (MSX) and Dermo (also known as perkinsosis), in several eastern Canadian provinces, the Canadian Food Inspection Agency (CFIA) is introducing new oyster movement controls covering Prince Edward Island, Nova Scotia, New Brunswick, Newfoundland and Labrador and Québec.
Neither MSX nor Dermo pose risks to human health or food safety, but they can cause increased oyster mortality and decreased growth rates.
Starting on September 2, the waters of eastern Canada — meaning Prince Edward Island, New Brunswick, Nova Scotia, Newfoundland and Labrador and Québec — will be declared as areas where the aquatic animal diseases, MSX and Dermo, are present or very likely to be present. This means that the movement of oysters which are not yet ready for commercial sale will be managed according to the CFIA’s established Domestic Movement Control Program (DMCP).
Under the DMCP, oysters that have been grown to commercial size and processed for human consumption can still be exported and sold. However, oysters that are not ready for the commercial market (and are still growing) are not permitted to be moved outside of the declared areas.
These changes simplify the permitting process for oyster growers, harvesters and processors in eastern Canada, as CFIA permits will no longer be required for the movement of oysters or gear within the declared areas. Fisheries and Oceans Canada (DFO) continues to manage oyster movements within and between provinces in eastern Canada through the Introductions and Transfer (I&T) Licensing Program, in collaboration with the respective provincial authority and, when appropriate, in consultation with the CFIA.
Dermo was found for the first time in N.L. on June 5 in farmed oysters in Notre Dame Bay. The first case of Dermo was confirmed in P.E.I. in farmed oysters from samples collected in Egmont Bay, P.E.I. on July 4.
“At this time, Dermo has not been detected in any other waterways in Newfoundland and Labrador,” said the CFIA.
“The known, extensive commercial movement of oysters, in addition to the current diagnostic and epidemiological evidence, has shown that MSX and Dermo are present or highly likely to be present in numerous bays and rivers across marine waters of eastern Canada. Good biosecurity practices such as cleaning, draining and drying watercraft and equipment help prevent the spread of aquatic diseases and invasive species. However, due to the uncontrolled movement of the marine waters, the risk of spread cannot be fully contained,” said the CFIA.
Multinucleate sphere unknown (MSX) was first detected in P.E.I. oysters on July 11, 2024. On Feb. 7, the CFIA declared P.E.I. as an area where MSX is known or is highly likely to occur.
“This decision was made because of evidence showing that MSX is already present, or is highly likely to be present, in most P.E.I. marine waters,” said the CFIA.
Since the spring oyster fishery reopened, there have been some areas of high oyster mortality due to MSX; however, not all infected molluscs show signs of disease, said the CFIA.
“MSX typically affects market size oysters (two inches or larger) and the associated mortality rate can go up to 90–95 per cent. Growers should watch for increased mortality, sick looking oysters such as: gaping shells and/or failure to close quickly when disturbed, yellow-brown spots on the inside of the shell, mantle recession, slow shell growth, as well as thin and watery oysters,” advised the CFIA.
The CFIA, Fisheries and Oceans Canada (DFO) and the eastern provinces continue to meet with industry members and stakeholders to provide regular updates and address questions and concerns.
