Traceability case study – Shellfish (oysters)

Traceability case study – Shellfish (oysters)

Fresh oysters on plate with lemon

This case study illustrates traceability in a fresh oyster supply chain from the restaurants serving the oysters back to the oyster bed form which the oysters were harvested. The case study is based on an incident involving illness following eating fresh oysters and an investigation to determine the cause or source of contamination..


In November a Northern local authority (LA) contacted the FSA incidents team to advice of two incidents involving cases of illness associated with consumption of raw oysters. Five diners eating oysters in one restaurant reported illness and 2 in another restaurant. Traceability records held at the restaurants identified that the suppler (shellfish merchant) of the oysters to both restaurants was located in another part of the country.

The FSA contacted the relevant LA in that area to obtain additional information. This included details of the supplier, whether any other complaints regarding the implicated batch of oysters had been received by the supplier, details of other businesses supplied with the same batch, and where the supplier had obtained the oysters from.

The investigation

The oysters from the batch supplied to the restaurants had been obtained from a shellfish purification establishment. Additional information obtained from this business included the source of the oysters (oyster bed), confirmation that no pollution event had occurred to the oyster bed, the date and time the batch was purified and the end product test results.

In the subsequent January a further 12 incidents involving over 200 reports of illness ‘associated’ with the consumption of raw oysters were reported from different restaurants and hotels in various locations across England and Wales. The resulting investigation identified that a number of different suppliers, purification establishments and oyster beds were involved.

One step back and one step forward

The case study comprises an example of traceability analysis for each business in the oyster supply chain, from the harvest bed to the restaurant serving the oysters to the diners. It is given to illustrate the application of the one step back and one step forward requirement for traceability by each business. The application of traceability in practice will depend on the nature and size of a business.