Sanitation Management

Marine waters from which bivalve molluscan shellfish are harvested or grown must be monitored, evaluated for pollution, and classified in order for approved harvesting to take place. It is necessary that the water quality of shellfish growing areas be surveyed, and that actual and potential pollution be identified so as to minimize potential health risks associated with consuming shellfish.

Primary responsibility for these sanitary surveys rests with Environment Canada through the Canadian Shellfish Sanitation Program (CSSP). The designation of safe growing waters, the patrolling of shellfish harvesting areas, and the harvesting, processing, and distribution stages of the shellfish industry are all regulated by this program. Shellfish growing areas require frequent sanitary surveys to ensure that water quality meets approved federal standards for harvesting. The sanitary control of the shellfish industry ensures that shellfish are harvested and processed under sanitary conditions.

Sanitary water quality surveys are used to determine whether shellfish growing waters are appropriate for the harvesting of shellfish. The sanitary quality assessment of growing areas identifies and evaluates those factors influencing the sanitary quality of the water. Shellfish growing water surveys can be divided into two components: bacteriological surveys and shoreline surveys. The former refers to the measurement of faecal coliform pollution indicators in the growing areas while the latter describes the studies required to identify and quantify possible pollution sources including movement, dilution and dispersion of possible pollutants in shellfish growing areas. The primary objective of the surveys is to reduce bacterial contamination such that the consumers are protected from potential threats associated with eating contaminated shellfish.

Following such surveys, the actual and potential growing areas are classified as to their suitability for the harvesting of shellfish according to accepted water quality criteria and general sanitary conditions in the growing area. Depending on water quality and the results of the shoreline and sanitary surveys, several classifications are possible which permit or restrict varying degrees of harvesting. Shellfish growing areas in Canada may be classified as Approved, Conditionally Approved, Closed or Prohibited. Each classification is based on the bacteriological quality of the growing waters and the known potential sources of pollution.

For more detailed information on the growing area classifications, see also:

• CSSP Classification of Growing Areas

For the evaluation of the sanitary conditions of shellfish growing waters a class of indicator organisms are commonly used in the determination of sewage pollution. The faecal coliform bacteria, Escherichia coli, are chosen because of their relative ease of detection and their viability in the aquatic environment. Fecal coliforms have a high probability of being associated with faecal matter because they originate in the digestive tract of warm-blooded animals. 

Molluscan bivalve shellfish have the ability to concentrate chemical contaminants, including pathogenic micro-organisms, in their tissues. Contaminants from the water and sediments which accumulate can lead to levels that are toxic, and when consumed, have the potential to contribute to a public health hazard. Since these waters are the pathway by which contaminants are introduced to shellfish, the probable presence or absence of pathogenic micro-organisms in shellfish growing waters is important in deciding how shellfish obtained from an area should be used. 

The CSSP has established levels of contamination of faecal coliform in seawater. This helps managers to properly classify growing areas with respect to pollutant levels, which is of paramount importance in determining the potential safety of shellfish. Insuring that shellfish are harvested from pristine growing waters that are free of contamination is of primary concern to shellfish growers and regulators.

Safeguarding the safety and increasing quality assurance of shellfish products is critical to marketing farm shellfish. The rapidly developing shellfish aquaculture industry places an increasing demand on the monitoring and classification programs to provide and maintain this strict assurance of product safety. Increased monitoring and classification activities of new growing areas may involve additional verification, systematic random sampling or adverse condition monitoring and/or conditional management. The inclusion of shellfish farmers in these activities can make program delivery more effective.

Growing water sampling surveys involve standard sampling procedures using aseptic techniques to collect sanitary water samples. The samples are analyzed in laboratories for faecal coliform bacteria and the results are used in conjunction with sanitary survey data to classify the shellfish growing waters and to delineate closure boundaries. The minimum criteria for evaluating bacteriological sampling results includes the consideration of a series of samples collected over a period of time. The extent of shellfish growing water surveys for a given area depends on the level of knowledge of both water quality and pollution sources. There are two sample collection methodologies that have been designed for sanitary survey programs and they are: adverse condition sampling and systematic random sampling.

Adverse Condition Sampling

In shellfish growing areas affected by point sources of pollution, samples must be collected under adverse or “worst-case” conditions. Adverse conditions can be defined as those meteorological, hydrographic, seasonal events or point source discharges that have historically resulted in elevated faecal coliform levels in a particular growing area. In areas affected by point sources of pollution the classification decision is determined using only water sampling results that are collected during adverse conditions.  The factors are assessed to determine their effect on water quality. An analysis of bacteriological sampling results include a minimum of fifteen of the most recent water samples collected under adverse conditions from each station comprising the survey. This helps to effectively determine the adverse conditions that may affect the distribution of pollutants over the growing area. In shellfish growing areas that are not affected by point sources of pollution, a systematic random sampling strategy may be substituted for adverse condition sampling.

Systematic Random Sampling

Systematic random sampling involves the collection of water samples from established sites. A random sampling schedule is used to ensure that samples are collected with equal chance of seasonal weather conditions and tidal variations. A minimum of the thirty most recent randomly collected samples from each sample station is used for consideration. Following water sampling, the samples are transported back to laboratories where a data analysis can be conducted which will indicate faecal coliform levels. In order for random sampling to be a valid and reliable means of monitoring water quality, the sampling must be scheduled regardless of environmental condition. Thus, sample collection is scheduled sufficiently far in advance to support random collection with respect to environmental conditions.

If pollution events may be quantified, or are predictable, the sanitary quality of each area is reviewed as often as necessary and management plans may be established which limit harvest activities where there may be a risk of water quality degradation. Management plans are developed for shellfish growing areas that are either designated as conditionally approved or conditionally restricted. The plans include an evaluation of the potential sources of pollution that may affect the area and their correlation with the predictable environmental conditions or other factors affecting the distribution of pollutants in the area. The closures are implemented when Environment Canada classification surveys show that the waters exceed the applicable sanitary guidelines of the CSSP.

Direct industry involvement in these programs may require growers to become trained in sampling and surveying procedures, taking responsibility for sampling specific areas, and establishing rules of conduct with government regulators which provide assurance of quality control and compliance. As a component of the Shellfish Monitoring Project, a standard training curriculum, industry field data sheets, and monitoring agreements have been developed to involve Canadian shellfish producers in sanitary monitoring of shellfish growing waters at farms. The involvement of shellfish farmers in water quality monitoring can be an important part of farm based quality assurance programs. During the CAIA Shellfish Monitoring Project initiative, industry sampler involvement was tested in pilot projects. Industry involvement in these programs will potentially lead to the development of mechanisms to deal with seasonal problems and degrading water quality. Other jurisdictions such as Maine, California, and New Zealand already rely on participation of industry, public, or stakeholder representatives to provide monitoring services.