Feld L, Jakobsen HH, Göke C, Ellegaard-Jensen L, Hendriksen NB, Rømer JK & Jensen AN, 2022. Sanitary survey rapport 18. Lillebælt og det Sydfynske Øhav. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 96 s. - Teknisk rapport nr. 250. http://dce2.au.dk/pub/TR250.pdf
Regulation (EU, 2019) of the European Parliament and the Council of 15 March 2019 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 and the associated sampling plan must be based on so-called ”sanitary surveys”. A sanitary survey assesses the interactions between potential sources of microbial pollution, climate conditions and oceanography in the area. The EU Commission's guidance for conducting a sanitary survey forms the basis for this report. However, in some instances, the Danish practice for microbiological sampling frequency and the previous classification are used. The Danish procedure is described in the Executive Order on mussels etc., called “Muslingebekendtgørelsen” (BEK no. 1793 of 02/12/2020), which is summarised in Appendix 7.
The report covers the Danish area Lillebælt and the inner waters south of Funen, consisting of twelve production areas P74-P80 and P84-P88 located in Lillebælt and the coastal waters south of Funen. The production areas P74-P80 are located in Lillebælt and stretch from Fredericia north to Als and Augustenborg Fjord south. P84-P88 are the coastal waters south of Funen, including waters west of Als to Langeland east. The report figures marked the production areas with a bold blue line.
The report is a revision of the previous report for Lillebælt and the inner waters south of Funen (Larsen et al., 2017), extended to also include P88. Experience has shown a difference in the significance of the topics covered in the individual appendices for potential microbiological contamination of the production areas. In addition, for some topics, no significant changes in sources of microbial contamination were expected to have occurred within the previous five- to six-year period. Therefore, it was decided that no new data should be collected for the appendices covering these topics. Instead, this report refers to the corresponding appendix in the previous report (Larsen et al., 2017).
The mussel fishery in Lillebælt and the waters south of Funen have primarily targeted blue mussels. Larger catches of blue mussels have historically been obtained until 2014-2016 in some parts of the report area, including P74 Lillebælt north, P76 Lillebælt south and P78 Barsø. Since 2017, the fishery has moved to P79 Åbenrå Fjord and P80 Als Fjord. The density of blue mussels in the area varies between years, and it is impossible to predict the potential stock precisely for the years to come. However, large parts of the report area are regulated by permits or restrictions on the mussel fishery. No permissions for mussel farming are registered within Lillebælt and the coastal waters south of Funen.
The report is supported by publicly available data from monitoring microbiological contamination in Lillebælt and the inner waters south of Funen. The concentrations of E. coli and Salmonella were determined in mussel samples taken at different sampling points within the active production areas. The report identifies the most precautionary fixed sampling points for future monitoring. Part of the data used in this report was collected from dynamic web pages belonging to, for instance, municipalities and Statistics Denmark (Danmarks Statistik). Therefore, it cannot be guaranteed that the accessed data will be persistently available.
From the Danish mussel surveillance, a limited set of historical data is available on E. coli in mussels, collected from the production areas within Lillebælt and the inner waters south of Funen over the last ten years (2012-2021). Four hundred and five samples were analysed for E. coli from seven (P74, P76-P80 and P86) out of the 12 production areas during this period. From each of the seven active areas, between 13 and 101 samples were analysed, with most samples analysed from P77. From the latest tree-year period (2019-2021), samples were only collected from the areas P77, P79, P80 and P86. However, in all these cases, an inadequate number of samples (< 24) were collected to qualify for classification.
The samples analysed were collected exclusively from the sea floor and consisted of blue mussels (Mytilus edulis). Additionally, 71 samples were analysed for Salmonella (during 2012-2017), and all were negative.
The overall data from the area Lillebælt and the inner waters south of Funen revealed good microbiological hygiene in the samples investigated for E. coli, with 97 % from the latest ten-year period having low levels ≤ 230 MPN E. coli/100 g (and meeting A-class status). However, the ratio of samples in the A-class varied between the different seven active areas, from 92-95 % in P76-78 to 98-100 % in the remaining four production areas, although the number of samples analysed from each area was too low to determine whether this difference was statistically significant.
In summary, the sanitary survey of Lillebælt and the inner waters south of Funen indicated good microbiological hygiene in most production areas. Yet, only limited microbiological data sets exist from the latest three-year period; for all production areas, this was insufficient to obtain a classification. A statistical analysis of the microbiological hygiene in the area during the last ten years could also not be made because of the limited number of samples.
Based on assessing point sources and transport routes for microbiological contamination (sanitary survey) and considering the historical microbiological data for Lillebælt and the coastal waters south of Funen, a microbiological monitoring programme was recommended for each of the production areas (P74-P80 and P84-P88). In each of the recommended monitoring programmes, proposals for a sampling location, classification status (preliminary or permanent) and a sampling plan were outlined.
Based on the results from the sanitary survey of the production areas, supported by the historical data sets on the number, frequency and concentration of E. coli, it was assessed that none of the production areas was considered suitable for permanent classification. This was due to an insufficient number of analysed samples (less than 24) within the past three years (2019-2021). Furthermore, there was an absence of samples collected during the last year (2021), except for a few samples collected in P80. Considering that unclassified areas are to be upgraded to permanent classification, the EU guideline requires that the collected data include at least 12 samples for the last six months or 24 samples over the last three years. This implies a future sampling frequency of at least eight samples per year over three years.
The report is divided into main chapters that summarise identified microbiological contaminants. Appendices 1-4 serve as a starting point for the main chapters. In addition, relevant data representing characteristics of the areas, as described in the previous sanitary survey for Lillebælt and the inner waters south of Funen, have been included. Appendix 5 is a detailed review of all historical microbiological data from mussel monitoring consisting of the fishery’s own monitoring and the Danish Veterinary and Food Administration’s[1] 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 were 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 within the auspices of the Water Framework Directive.
