The identification, analysis and control of hazards that present a risk of contamination of live shellfish
Although the Safe Food for Canadians Regulations (SFCR) came into force on January 15, 2019, certain requirements are being phased in over the following 12 to 30 months. For more information, refer to the SFCR timelines.
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The purpose of this document is to provide information on the hazards that can be present in live shellfish and some example control measures that could help prevent or reduce the risk of contamination of the shellfish. This is not intended as an exhaustive list of measures. Always ensure that the control(s) chosen are tailored to the uniqueness of your business and shown to be effective for your situation.
Pathogens can be found in the waters of the shellfish harvest, wet storage or relay areas and can present a risk of contamination of the shellfish. The shellfish can accumulate and become contaminated with the pathogens when filtering the surrounding water to feed. The presence of these pathogens in shellfish consumed in a raw or partially cooked state can present a risk of injury to human health.
The pathogens can be naturally occurring or the result of contamination by human or animal fecal matter. Naturally occurring pathogens include bacteria such as:
- Vibrio vulnificus
- Vibrio parahaemolyticus
- Vibrio cholerae
Pathogens from human and animal fecal sources include bacteria and viruses such as:
- Salmonella spp.
- Shigella spp.
- Campylobacter jejuni
- Yersinia enterocolitica
- Vibrio cholerae
- Hepatitis A
Example sources of pathogens include:
- discharge from waste water treatment plants
- sewage contamination
- processing establishments
- direct discharge of sewage from boats, harvest vessels and maintenance vessels in shellfish areas
- private homes and malfunctioning septic systems
- agricultural animals
- wildlife, marine mammals or birds
- natural events such as herring spawning which can attract birds or mammals
- birds roosting on aquaculture equipment such as floating bags or buoys
Natural toxins can be found in the waters of the shellfish harvest areas and can present a risk of contamination of the shellfish. Most of these toxins are produced by naturally occurring marine algae (phytoplankton). The toxins can accumulate in shellfish when they filter the water to feed on the algae. Natural toxins cannot be reliably eliminated by heat treatment (cooking) so their presence in shellfish consumed in a raw or cooked state can present a risk of injury to human health.
The natural toxins that can be found are:
- Amnesic shellfish poison (Domoic Acid)
- Diarrhetic shellfish poison (Okadaic Acid)
- Paralytic shellfish poison (Saxitoxins)
Environmental Chemical Contaminants and Pesticides
Environmental chemical contaminants and pesticides can be found in waters of the shellfish harvest areas and can present a risk of contamination of the shellfish. Chemical contaminants cannot be eliminated by heat treatment (cooking) so their presence in shellfish consumed in a raw or cooked state can present a risk of injury to human health.
Chemical contaminants include:
- Heavy metals such as Mercury
- Pesticides such as Dichlorodiphenyltrichloroethane (DDT), Hexachlorobenzene (HCB) (BHC), heptachlor, chlordane, dieldrin, endrin, aldrin, mirex
- Hydrocarbons such as petroleum
Example sources of chemical contaminants include:
- Pulp mills
- Urban or agricultural runoffs
The hazards that can present a risk of contamination of the shellfish need to be controlled with measures that are shown by evidence to be effective.
Controls at the harvest site
Control measures to prevent the harvesting of shellfish contaminated by pathogens, natural toxins and environmental contaminants are administered by Government authorities. In Canada, the control measures are jointly administered by the Canadian Food Inspection Agency (CFIA), Environment and Climate Change Canada (ECCC) and Fisheries and Oceans Canada (DFO) under the Canadian Shellfish Sanitation Program (CSSP).
Under the CSSP, the water quality in shellfish growing and harvest areas is surveyed to identify actual and potential sources of pollution. The areas are classified as to their suitability for the harvesting of shellfish according to accepted water quality standards and general sanitary conditions in the shellfish area. The levels of natural toxins are monitored to control the harvesting of toxic shellfish. The CSSP provides information about the shellfish areas that are open or closed to shellfish harvesting.
Shellfish can only be harvested in contaminated areas when a license, under the Management of Contaminated Fisheries Regulations, has been issued to harvest the shellfish and the shellfish are decontaminated using an approved depuration or relay operation. Refer to to the document Depuration of bivalve shellfish and section 9.4.2 of the CSSP manual
For areas subject to a conditional management plan, based on the operation of a waste water treatment plant, shellfish can only be harvested inside the response line identified on the classification map.
Control measures to reduce the risk of Vibrio parahaemolyticus in live oysters are discussed in the document Measures to control the risk of Vibrio parahaemolyticus in live oysters.
Control measures applied by an operator
Control measures to prevent harvesting or sourcing of contaminated shellfish should ensure that the shellfish are sourced from:
- harvest areas classified as approved or conditionally approved and in the open status
- check that the harvest area status for sanitary closures, biotoxin closures, emergency closures posted by DFO on websites or by other means of communication with DFO
- maintain a list of commercial shellfish harvesters that hold a licence issued by Fisheries and Oceans Canada
- establish harvest plans that identify, in advance, the harvesters and location of harvest
- when receiving the shellfish, verify that they were appropriately tagged with complete and accurate harvest information and question harvesters on the harvest location and its status at the time the shellfish were harvested
- verify the marine biotoxin levels on a regular basis when shellfish are harvested from offshore harvest areas
- harvest areas that have not been impacted by sewage contamination
- a depuration facility or relay operation only when the shellfish were decontaminated using an approved method.
- harvest vessels that have adequate control measures to prevent contamination of shellfish by human waste and that have sanitary practices on the use of human waste receptacles or washroom facilities
- have a Supplier Food Safety Assurance Program to help ensure controls are in place to prevent contamination of the shellfish from human waste
- harvesters and suppliers that have time and temperature controls to prevent the growth of pathogens at harvest, and after harvest during the holding and transportation of the shellfish
- have a SFSA to ensure controls are in place to prevent the growth of pathogens
- observe harvesting practices
- an integrated multi-trophic aquaculture site only when an Integrated Multi-trophic Aquaculture Management Plan (IMTAMP) approved by the Regional Interdepartmental Shellfish Committee (RISC) is in place as described in the CSSP manual
- have a SFSA to ensure that controls are in place to prevent contamination of the shellfish
- a near shore wet storage area only when the area is in the open status at the time the shellfish are removed
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