Question Period Note: Oyster Disease

• Our Government understands the importance of protecting the health of Canada's aquatic resources and the multi-billion dollar export market for fish and seafood products.
• Multinucleate Sphere Unknown, known as MSX, poses no risks to human health or food safety, but it is a serious disease for American oysters that can cause significant oyster mortality of both cultured and wild oysters.
• My Department is collaborating with the Canadian Food Inspection Agency, the provinces of Prince Edward Island and New Brunswick, and with industry to contain the outbreak, limit the spread of MSX, and respond to industry priorities related to the disease.

General
• Canada’s National Aquatic Animal Health Program, co-delivered by the Canadian Food Inspection Agency (CFIA) and Fisheries and Oceans Canada (DFO), is responsible for preventing the introduction and/or spread of significant diseases of finfish, mollusks, and crustaceans.
• CFIA is the lead agency with legislative authority under the federal Health of Animals Act. CFIA is responsible for enforcing regulations governing import and export, disease management, and surveillance activities. DFO provides diagnostic testing services, research support, and scientific advice.
• On Canada’s east coast, DFO issues introductions and transfers (I&T) licenses under the Fishery (General) Regulations to authorize the intentional release and transfer of live aquatic organisms into fish-bearing waters or fish-rearing facilities when the proposed transfer poses low ecological, disease, and genetic risks.
• Risks associated with each movement, including shellfish for aquaculture purposes, are assessed by federal-provincial/territorial I&T Committees, which have representation from DFO and provincial/territorial governments.

MSX
• Multinucleate sphere unknown (MSX) is a disease in oysters caused by the parasite Haplosporidium nelsoni. It is a serious disease that can cause significant mortality of both cultured and wild oysters.
• In Canada, the disease was first detected in Bras d’Or Lake, Nova Scotia in 2001, and more recently found in the waters of Prince Edward Is
• land (P.E.I.) in June 2024, and New Brunswick in November 2024.
• Both the CFIA and DFO, through their respective processes, implemented oyster movement controls to prevent the introduction and spread of this disease to other areas. Currently, these include the declaration of P.E.I. as an infected area in February 2025 and a Primary Control Zone (PCZ) in New Brunswick where the disease has been detected or is suspected to exist. Testing of other sites in the Atlantic provinces is ongoing. As of April 8, 2025 DFO’s laboratories have tested more than 9,000 samples for MSX.
• Reported mortalities of oysters thus far are from the original detection site in Bedeque Bay, P.E.I. Significant mortalities have not yet been reported in farmed or wild populations at other suspected or confirmed infected sites; however, samples taken from oysters transported from infected sites to other sites have tested positive for MSX. Further, the parasite can be dormant or suppressed for long periods of time.

Dermo
• Dermo is a disease in oysters caused by the parasite Perkinsus marinus. It is a serious disease that can cause significant mortality of both cultured and wild oysters.
• Based on tests conducted at DFO’s aquatic animal health laboratory in Moncton, CFIA confirmed a detection of Dermo disease in New Brunswick on November 19, 2024 and in Nova Scotia on November 27, 2024. No abnormal mortalities were observed at these sites.
• These were the first detections in Canada. Consequently CFIA notified the World Organisation for Animal Health.
• Both CFIA and DFO, through their respective processes, implemented oyster movement controls to prevent the introduction and spread of Dermo to other areas. Currently these include PCZ in New Brunswick and Nova Scotia. Testing of other sites in the Atlantic provinces is ongoing. As of April 8, 2025, DFO’s laboratories have tested more than 5,200 samples for Dermo.

If pressed on measures being taken to limit the spread of MSX
• We remain committed to continued collaboration with all parties to mitigate the evolving impacts of MSX.
• Working with the Canadian Food Inspection Agency, my Department is conducting testing of oysters to determine the presence and extent of MSX infection in impacted areas. As of April 8 2025, Fisheries and Oceans’ laboratories have conducted more than 9,000 tests for MSX throughout the Atlantic provinces.
• Given that MSX poses no risk to human health or food safety, this testing is not conducted for food safety purposes.
• My Department continues to collaborate with provinces through the Prince Edward Island and New Brunswick Introduction and Transfer Committees on the need to authorize the intentional release and transfer of live oysters, while the Canadian Food Inspection Agency provides technical expertise on MSX in an advisory role to this Committee.

If pressed on what the Department is doing to support MSX research
• My Department is providing up to $1 million in funding for external experts over the next two years, to support scientific research toward addressing knowledge gaps in our understanding of MSX.
• On November 13-14, 2024, my Department co-hosted a Science Summit on MSX with the Province of Prince Edward Island, which gathered experts and partners to discuss what we know about MSX as well as priority areas for additional research.

If pressed about Dermo disease in oysters
• The Canadian Food Inspection Agency confirmed the detection of Dermo disease in farmed American oysters in New Brunswick and Nova Scotia in November 2024 (based on regulatory diagnostic testing conducted at my Department’s National Aquatic Animal Health Laboratory System).
• While Dermo disease poses no risks to human health or food safety, it is a serious disease for American oysters.
• This is the first detection of Dermo disease in Canada. As of April 8, 2025, Fisheries and Oceans Canada’s laboratories have conducted more than 5,200 tests for the detection of Dermo throughout the Atlantic provinces.
• My Department, the Canadian Food Inspection Agency, provinces, the industry, processors, fish harvesters, and academic institutions are working closely together to coordinate a response and the management of both diseases.