Shellfish Harvest Area Closures Related to Significant Weather Events

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Information for shellfish stakeholders

The Canadian Shellfish Sanitation Program (CSSP) is a molluscan shellfish food safety program. It is administered by the Canadian Food Inspection Agency (CFIA), Environment Canada and Fisheries and Oceans Canada.

Food safety is a top priority of the Government of Canada. The objective of the CSSP is to minimize human health risks associated with consuming bivalve molluscan shellfish (mussels, clams, oysters, cockles, etc.).

The program allows for emergency closures in response to:

  • significant weather events (for example, heavy rainfall and flooding), and
  • other unexpected events (for example, oil or hazardous substance spills or sewage overflows).

All stakeholders are encouraged to refer to the Canadian Shellfish Sanitation Program Manual of Operations for specific information related to the control of shellfish in Canada (namely, Appendix VIII: Protocol for Emergency Closure of any Shellfish Growing Area.

Who is responsible for administering the Canadian Shellfish Sanitation Program (CSSP)?

Three federal government organizations administer the program.

Canadian Food Inspection Agency (CFIA)

The CFIA is the lead agency administering the CSSP. Additional CFIA responsibilities in regard to the program include:

  • conducting microbiological testing of shellfish;
  • verifying that processing, importing, exporting and labelling of shellfish complies with government regulations (Fish Inspection Act and Regulations and Food and Drugs Act and Regulations);
  • administering the Marine Biotoxins Control Program; and
  • liaising with foreign governments on matters relevant to shellfish sanitation.

Environment Canada

Environment Canada is responsible for evaluating the environmental conditions of shellfish harvesting areas. It does this by:

  • monitoring marine water quality in shellfish harvesting areas, and
  • assessing pollution sources so that growing waters meet established international sanitary standards.

Findings from these evaluations form the basis of:

  • recommendations to the CSSP partners for the appropriate classification of shellfish harvesting areas, and
  • recommendations to Fisheries and Oceans Canada to close or open contaminated areas as required.

Environment Canada's Meteorological Service of Canada is responsible for forecasting weather and issuing weather warnings.

Fisheries and Oceans Canada

Fisheries and Oceans Canada is responsible for:

  • opening and closing shellfish harvest areas, and
  • enforcing closures under the authority of the Fisheries Act and the Management of Contaminated Fishery Regulations.

In a public health emergency, Fisheries and Oceans Canada has the authority to restrict harvesting of shellfish from growing areas.

Fisheries and Oceans Canada communicates shellfish harvesting closures through:

When are rainfall warnings issued?

The Meteorological Service of Canada issues a rainfall warning when heavy or prolonged rainfall is sufficient to cause local or widespread flooding or flash floods. Significant rainfall can cause overflows of sewage treatment and collection systems, as well as other pollution resulting from surface runoff from land. Shellfish in adjacent waters can be contaminated from such discharges and pose a risk to human health if they are consumed.

How much rain, over how many hours, will result in a closure?

Environment Canada monitors rainfall warnings issued by the Meteorological Service of Canada. It will make recommendations to close an area based only on recorded rainfall amounts, not on predicted rainfall amount.

Stakeholders are encouraged to monitor rainfall warnings issued by the Meteorological Service of Canada. Note that not all significant rainfall amounts following a rainfall warning will result in a shellfish closure.

There are no set criteria for triggering a rainfall-based closure. Rainfall events will be assessed on a case-by-case basis. The impact of rainfall varies from region to region across the country and even within a region. Where warranted, the extent of closures will depend on the impact to the harvesting areas.

The risk of contamination depends on a number of factors, including:

  • the amount of precipitation;
  • the intensity of precipitation;
  • duration;
  • time of year;
  • weather conditions preceding storms;
  • ground saturation;
  • likelihood of flooding and sewage overflows;
  • trends in the freezing and thawing cycle; and
  • adjacent land use activities.

For example, 110 millimetres of rain falling over 72 hours may not have the same impact as 90 millimetres of rain falling over an 18-hour period. Likewise, moderate rainfall may have a greater impact when it follows a prolonged dry period than heavy rain during the predominantly wet season.

A heavy rainfall may pose different risks during different seasons. For example, an agricultural area where manure is spread in the spring poses a higher risk during floods than the same field in the winter.

To maintain the integrity of the Canadian Shellfish Sanitation Program, and in turn the reputation of the shellfish industry, emergency closures are, and will continue to be, essential for maintaining consumer safety.

Are shellstock or water samples taken before an emergency closure?

Samples are not taken before an emergency closure. Emergency closures are required immediately to prevent contaminated shellfish from reaching markets and consumers.

What data does Environment Canada use to recommend a closure to Fisheries and Oceans Canada?

Environment Canada has been conducting shellfish sanitary surveys across Canada for over 30 years. The assessment of more than 700,000 water quality samples collected during this time, coupled with information on pollution sources, has provided Environment Canada staff with considerable expertise in assessing impacts from rainfall-induced pollution.

There is ample evidence that fecal coliform concentrations increase markedly with rainfall in many shellfish waters.

Other countries use similar information to restrict harvesting of shellfish as a result of significant weather events. The Meteorological Service of Canada uses internationally-accepted forecast models to predict weather events. These models are used as the basis for public forecasts and rainfall warnings. Canadian Shellfish Sanitation Program staff at Environment Canada use the same publicly available forecasts and rainfall warnings, as well as other information such as flood warnings, as alerts that conditions in shellfish harvesting areas could deteriorate.

It is imperative that areas affected by contamination be closed immediately to all harvesting until the shellfish can self-cleanse and are again safe for human consumption.

What can shellfish harvesters do to prepare for a potential closure due to a significant weather event?

The Canadian Shellfish Sanitation Program partners recommend that harvesters and processors monitor public weather forecasts closely for significant weather events and rainfall warnings. A rainfall warning does not mean that shellfish areas will be closed to harvesting, nor does it mean that every rainfall-related closure will be associated with a previous rainfall warning; each rainfall event is assessed on a case-by-case and location-by-location basis. However, a rainfall warning should be considered as an alert that:

  • an approaching storm may overload wastewater treatment facilities and their collection systems, and
  • there could be excess surface runoff and flooding warranting a shellfish harvesting closure.

Shellfish growers should adjust their harvesting plans accordingly.

These rainfall warnings will allow harvesters to take appropriate measures before a storm, and to prepare for such closures if they are deemed necessary. There are a number of sources for such information.

What additional steps can the shellfish processing industry take to protect public health and their markets?

The effects of weather-related events have been identified as a potential food safety hazard for wild and aquaculture-harvested shellfish products.

Federally registered establishments who process bivalve molluscan shellfish are required to review their Hazard Analysis and Critical Control Point (HACCP) plans annually, as a minimum. A review of their HACCP plans will help determine if additional control measures for incoming products are required, or if current control measures need revision. This will ensure that contaminated product is not processed and then distributed to market.

What is the procedure for re-opening an area?

Emergency closures due to rainfall remain in effect for a minimum of seven days to allow proper cleansing of shellfish.

The cleansing process depends on a variety of factors, including:

  • the species;
  • water temperature;
  • weather; and
  • the amount of initial contamination.

Water quality and shellstock samples are collected and analyzed in key areas. Once samples are collected, approved laboratory methods require several days before results are available. If the results meet the appropriate Canadian Shellfish Sanitation Program standards, Environment Canada and the Canadian Food Inspection Agency will recommend to Fisheries And Oceans Canada that the area can be reopened.

How are openings and closures related to emergency events communicated to stakeholders?

Each region has a communication procedure for openings and closures related to emergency and non-emergency events. The official source for this information is the applicable Fisheries and Oceans Canada website for the region.

Once Canadian Shellfish Sanitation Program partners are satisfied that an opening or closure is required, Fisheries and Oceans Canada will take steps to prepare a prohibition order (or rescind a prohibition order if an area is being re-opened). Fisheries and Oceans Canada posts this information to their website.

Notification can take the form of various channels, including:

  • email;
  • a news release;
  • website updates;
  • telephone calls; and/or
  • fishery notices.

All affected stakeholders should ensure they are on the appropriate distribution lists to receive these notifications, by contacting their local Fisheries and Oceans Canada office.


If you have any questions regarding significant weather events or shellfish safety, please contact your local CFIA office.

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