Larsen, M.M., Jakobsen, H.H., Göke, C., Hendriksen, N.B., Rømer, J.K., Mohn, C., Jensen A.N. & Schultz, A.C. 2018. Sanitary survey rapport 6: Visby, Vildsund og Thisted. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 110 s. - Teknisk rapport fra DCE - Nationalt Center for Miljø og Energi nr. 119.
http://dce2.au.dk/pub/TR119.pdf
Regulation (EC) No 854/2004 of the European Parliament and the Council of 29 April 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 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 13.
The report covers production areas P23, P24, P25, P26, P27, P28, P30 and P32 situated in the northern and western part of the island of Mors located in Limfjorden at Visby, Vilsund and Thisted. The covered production areas within Limfjorden are marked ‘Rapportområde’ on the maps in this report.
The 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, however.
The report is supported by publicly available data from monitoring of microbiological contamination in Limfjorden north and west of Mors where the concentrations of E. coli and Salmonella are determined in samples of mussels etc. taken at different sampling points within each area. The report points to the most precautionary fixed sampling points for future monitoring.
In summary, the sanitary survey of Visby, Vilsund and Thisted identified a generally, with a few exceptions, microbially homogeneous and relatively clean area with only rare occurrences of critical microbial contamination.
The data set represents the 10-year period 2007-2016 and revealed that 98% of a total of 695 samples contains E. coli within the A-level (<230 E. coli/100 g); none of 184 samples were tested positive for Salmonella. However, the data covers only six of the eight mentioned production areas, no data being available from the P24 and P25. Further, No data is available from 2017 in the areas P27, P28 and P32 precluding classification.
Based on an assessments of sources and transport routes for microbiological contamination (sanitary survey) verified against historical microbiological data on Visby – Vilsund - Thisted), a microbiological monitoring programme is recommended for each of the production areas in Visby – Vilsund - Thisted.
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 set on the number, frequency and E. coli concentration in samples, production areas P25 and P26 are considered suitable for permanent classification with a future sampling frequency of at least eight samples per year over a three-year period. There is a lack of data on P25 during the summer (week 27 to 35). For area P30, lack of sampling in 2017 hinders permanent classification for the last three years, but until 2016 the area was classified as A. In contrast, the number of samples for areas P27 and P28 was too limited to allow classification since 2012 where an A-level was achieved, the level of classification in previous years being B. The remaining areas – P23, P24 and P32 – have either no data at all (P23 and P24) due to a ban on fishing or only data from 2009 and 2010 (P32). If areas without permanent classification 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 2-10 serve as starting point of the main chapters. Appendix 11 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.
