Shellfish Classification

Harvesting Classification and Sanitary Surveys

It is currently a requirement under EU legislation (EC Regulation 854/2004 Annex II) for all beds from which bivalve shellfish are harvested to have a Classification according to a microbiological standard based on the presence of the bacteria Escherichia coli.  

E. coli is used as an indicator organism for the presence of faecal contamination and shellfish are tested to obtain the number of colony forming units (CFUs) in 100g of flesh and intra-valvular liquid. E. coli occur naturally in the digestive tract of animals and humans and are generally considered harmless although there are strains, such as 0157:H7, which can cause illness in humans.

Classification Process

An application to have a shellfish bed classified can be made by contacting the Food Standards Agency (FSA).

Food Standards Agency

Once an application for Classification has been made, sampling of representative shellfish is normally undertaken on behalf of the FSA by the Local Authority Environmental Health Officers (EHO).  The EHOs send the shellfish samples to an accredited testing laboratory in order to assess the levels of E. coli CFUs in 100g of flesh and intra-valvular fluid.  A provisional Classification can normally be issued after sampling fortnightly for 3 to 4 months with full Classification being achieved after a full year’s results have been obtained, normally based on monthly sampling intervals.

There is also scope under a Memorandum of Understanding between the Food Business Operator (FBO) and the FSA for the FBO to submit additional samples for inclusion in the microbiological data set for a production area. This is known as the Harvesters Own Sample Protocol. The advantage of doing this is considered to be that a larger data set helps to identify contamination trends and may add to the stability of the Classification based on the 90% compliance.

The intention is that FBO sample results are considered alongside the FSA’s official control microbiological results dataset for the classification, closure or opening of the relevant production area.  An increase in microbiological data from a shellfish production area would increase the knowledge of the microbial contamination trends within the area and may benefit the stability of the area’s classification.

Classifications issued for shellfish harvesting beds are based on the following criteria in terms of how many CFUs are present:

Class A: A harvesting area where test results are shown to be consistently less than 230 CFUs of E. coli per 100g of flesh and intra-valvular liquid.

Class B: A harvesting area where 90% of samples have less than 4,600 CFUs of E. coli per 100g of flesh and intra-valvular liquid. The remaining 10% of samples must not exceed 46,000 E. coli per 100g.

Class C: A harvesting area where test results are shown to be less than a maximum limit of 46,000 CFUs of E. coli per 100g of flesh and intra-valvular liquid.

Prohibited Area: A harvesting area where test results are shown to be higher than 46,000 CFUs of E. coli per 100g of flesh and intra-valvular liquid.

Current Classifications for England and Wales can be found on the FSA website:

Current Classifications

Regulatory Monitoring Point results can be found on the Cefas website:

Regulatory Monitoring Point Results

Sanitary Surveys

Under EC legislation EU/854/2004, Section 6, of Annex II, if the competent authority (FSA) decides in principle to classify a new production area or re-laying area then a Sanitary Survey must be carried out. These surveys provide an inventory of the sources of pollution of human or animal origin likely to be a source of contamination for the shellfish harvesting or production area.

Information included in the surveys is as follows:

  • An examination of the quantities of organic pollutants which are released during the different periods of the year, according to the seasonal variations of both human and animal populations in the catchment area, rainfall readings, waste-water treatment etc.; 
  • Determination of the characteristics of the circulation of pollutants by virtue of current patterns, bathymetry and the tidal cycle in the production area;
  • Establishment of a sampling programme of bivalve molluscs in the production area which is based on the examination of established data, and with a number of samples, a geographical distribution of the sampling points and a sampling frequency which must ensure that the results of the analysis are as representative as possible for the area considered.

Where harvesting or production beds are already classified for other shellfish species then these Sanitary Surveys are a good reference source for establishing likely points of microbial contamination. Sanitary surveys are now in the public domain and can be accessed via:

Sanitary Surveys
Last updated: 4 May 2020