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No. 152: Sanitary survey report 10: Jutland's west coast (southern part)

Feld L, Larsen MM, Jakobsen HH, Göke C, Hendriksen NB, Rømer JK, Mohn C, Jensen AN & Schultz AC. 2019. Sanitary survey rapport 10: Jyllands vestkyst (sydlig del). Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 118 s. - Teknisk rapport nr. 152.  http://dce2.au.dk/pub/TR152.pdf


Regulation (EC) No 854/2004 of the European Parliament and the Council of April 29th, 2004 lays down specific rules for the organisation of official controls on products of animal origin intended for human consumption. Classification of production areas for live bivalve molluscs etc.[1] and the associated sampling plan are required to be based on so-called ‘sanitary surveys’. A sanitary survey is an assessment of the interactions between potential sources of microbial pollution, climate conditions and oceanography in the area. The EU Commission guidance for making a sanitary survey has formed the basis for this report. However, in certain cases, the Danish practice for microbiological sampling frequency and the previous classification on the basis of this is used. The Danish practice is described in ‘muslingebekendtgørelsen’, which is summarized in Appendix 11.

The report covers thirteen production areas P135-P147 situated in the North Sea from the coast of west Jutland north of Blåvands Huk to Fanø and the inner part of the Wadden Sea east of Rømø in the south. In the area covering the west coast of Jutland (southern part), no permissions for mussels farming are registered. Likewise no catches of mussels are recorded, because fishing for mussels in the Wadden Sea has been forbidden since 2008, e.g. due to the preservation of mussel eating wading birds. Oyster safaris on the mudflats for tourists or locals have been common around both Fanø (P131, P132, P133 and P138) and Rømø (P134, P135 and P136), but have been stopped around Fanø due to several reports of Norovirus symptoms from collected Pacific oysters in recent years. No reports have been found from areas around Rømø.

The report is supported by publicly available data from monitoring of microbiological contamination in the area at the west coast of Jutland (southern part) where the concentrations of E. coli and Salmonella are determined in samples of mussels etc. taken at different sampling points within each production area. The report points to the most precautionary fixed sampling points for future monitoring. For the use of this report, data and information have been collected through web pages from e.g. municipalities and Statistics Denmark (Danmarks Statistik). Since these web pages are continuously updated, it cannot be guarantied that the accessed data will be persistently available.

From the Danish mussel surveillance, a limited set of historical data is available for analyses of E. coli in mussels etc. collected from the west coast of Jutland (southern part). During the last 10 years (2009-2018), samples have been analysed from seven production areas (P135, P137, P140, P142, P143, P144, P147), while the remaining six production areas are not represented in the sampling data. From the seven active production areas, 286 samples have been analyzed for E. coli and 59 samples have been analyzed for Salmonella during the 10-year period. All samples were collected from the bottom and contained different species of mussels etc. Hence, 179 (63 %) of the samples consisted of surf clams (Spisula solida), 94 (33 %) common cockles (Cerastoderma edule), 7 (2 %) blue mussels (Mytilus edulis) and 6 (2 %) oysters (unidentified species).

The data revealed a generally good microbiological hygiene in the investigated samples with an average of 97 % of the samples within the levels ≤ 230 MPN E. coli/100 g, and no positive for Salmonella. Nine samples showed increased levels > 230 MPN E. coli/100 g and of these, one sample was collected during the last 3-year period in production area P144 in 2017. However, the data set showed a large variation in number and frequency of samples analyzed within the different production areas. As such, a much higher rate of samples was processed within the past years from P144 and P147 compared to the other production areas, and from the latest year (2018) sampling was only performed from P144 and P147.

In summary, the sanitary survey of the west coast of Jutland (southern part) identified a generally microbiologically clean area with only a few rare exceptions of relevant critical microbial contamination. However, for most of the individual production areas only a limited set of microbiological data exists, which prevents a statistical assessment of pollution from E. coli within the production areas, years or seasons. During the latest 3-year period (2016-2018), an adequate number of samples has been analysed from P144 and P147, but from the other production areas only a few sporadic or no samples have been analysed. Due to the limited amount of data, a comprehensive assessment of the hygiene status within the production areas is not possible. This implies that the impact of potential sources of pollution into the production areas cannot be satisfactorily evaluated.

This report recommends a microbiological sampling plan consisting of several designated sampling points and sampling frequencies for the individual production areas. It is further discussed whether merging of production areas into fewer areas could be an option in the future to reduce the number of sampling points, without compromising food safety.

Summary of recommended sampling programme

Based on an assessment of sources and transport routes for microbiological contamination (sanitary survey) verified as far as possible against historical microbiological data on the west coast of Jutland (southern part), a microbiological monitoring programme is recommended for each of the respective production areas P135-P147. In each of the recommended monitoring programmes, proposals for a sampling location, classification status (preliminary or permanent) and a sampling plan are outlined.

Based on the results from the sanitary survey of the production areas, supported by the historical data sets on the number, frequency and E. coli concentration in samples, it is assessed that only the individual production areas P144 and P147 are considered suitable for permanent classification with a future sampling frequency of at least eight samples per year over a three-year period. Assignment of a permanent classification is not possible for all the other production areas due to the lack of sampling in the past year (2018) and/or insufficient numbers of analyzed samples (less than 24) within the past three years. If unclassified areas are to be upgraded to permanent classification, the EU guideline requires that the collection of data should include at least 12 samples for the latest six months or data from 24 samples over the last three years.

The report is divided into main chapters that provide a summary of identified microbiological contaminants. Appendices 2-8 serve as starting point of the main chapters. Appendix 9 is a detailed review of all historical microbiological data from mussel monitoring consisting of the fishery’s own-check and the Danish Veterinary and Food Administration’s[2] verification projects of the industry’s microbial monitoring. It was decided that a so-called ‘shoreline survey’ is unnecessary because all possible sources of sanitary contamination are described in the sewage plans for the cities in the area, the beach water quality monitoring and in the analyses of the Ministry of Environment and Food under the auspices of the Water Framework Directive.

[1] Include live bivalve molluscs, echinoderms, tunicates and gastropods.


[2] Fødevarestyrelsen.