Shellfish harvest area closures related to significant weather events
Information for shellfish stakeholders
The Canadian Shellfish Sanitation Program (CSSP) is a bivalve molluscan shellfish food safety program. It is administered by the Canadian Food Inspection Agency, Environment and Climate Change 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 shellfish such as mussels, clams, oysters and cockles.
The program allows for emergency closures in response to:
- significant weather events such as heavy rainfall and flooding
- other unexpected events such as oil or hazardous substance spills or sewage overflows
All stakeholders are encouraged to refer to the section 6.2 of Canadian Shellfish Sanitation Program manual for specific information on emergency events.
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 and Climate Change Canada monitors both rainfall warnings and actual reported rainfall measurements. It will make recommendations to close an area based only on actual reported rainfall amounts, not on predicted rainfall amounts.
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
- time of year
- weather conditions preceding storms
- ground saturation
- likelihood of flooding and sewage overflows
- trends in the freezing and thawing cycle
- 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.
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 and Climate Change Canada use to recommend a closure to Fisheries and Oceans Canada?
Environment and Climate Change 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 areas.
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 and Climate Change 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 shellfish 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 monitor public weather forecasts closely for significant weather events and rainfall warnings. A rainfall warning does not necessarily 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
- there could be excess surface runoff and flooding warranting a shellfish harvesting closure
Shellfish harvesters 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.
- Environment and Climate Change Canada's public weather alerts on their Weather website
- New Meteorological Service of Canada weather app
- Email weather warning alert service
- Weather broadcasts on most local media outlets
- Weather radio Canada
- Recorded weather forecasts and warnings by telephone (listings can be found in the government offices pages of telephone directories)
What additional steps can the shellfish processors 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.
Federal licence holders who process bivalve molluscan shellfish are required to review their preventive control plan (PCP) on a regular basis. A review of their PCP 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
- the amount of initial contamination
Water quality and shellfish samples may be collected and analyzed in key areas. If 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 and Climate Change Canada and the Canadian Food Inspection Agency will recommend to Fisheries and Oceans Canada that the shellfish area can be reopened.
If samples are not collected, areas may remain closed for up to 21 days to mitigate the risk of shellfish contamination by viruses in untreated discharges from overburdened sanitary wastewater systems.
How are openings and closures related to emergency events communicated to stakeholders?
Fisheries and Oceans Canada is responsible for communicating openings and closures of shellfish harvesting areas. Once CSSP 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 on their website.
The CSSP shellfish map displays shellfish closures in real-time. The map also offers a subscription service that allows the public to receive email notifications of openings and closures in their area as soon as a prohibition order is posted or rescinded. This subscription service can be accessed via the map link, under the "I want to…" menu button.
Each region also has a communication procedure for openings and closures related to emergency and non-emergency events.
Notification can take the form of various channels, including:
- website updates
- area closure signs
- direct communication with bivalve shellfish harvesters, processors and local media
All affected stakeholders should ensure they are on the appropriate distribution lists to receive notifications, by contacting their local Fisheries and Oceans Canada office.
- Date modified: