# Commission Delegated Regulation (EU) 2020/689 of 17 December 2019 supplementing Regulation (EU) 2016/429 of the European Parliament and of the Council as regards rules for surveillance, eradication programmes, and disease-free status for certain listed and emerging diseases (Text with EEA relevance), Division 2: The restricted zone must have been defined on a case-by-case basis and:

Extent: E+W+S+N.I.

(a) it must take into account factors influencing the risks for the spread of infection with Bonamia ostreae including other establishments and wild molluscs, such as:
(i) the number, age, rate and distribution of the mortalities of molluscs on the establishment or group of establishments infected with Bonamia ostreae;
(ii) the distance to and density of neighbouring establishments or groups of establishments and wild molluscs;
(iii) the proximity to processing establishments, contact establishments or groups of establishments;
(iv) the species, especially susceptible species and vector species, present at the establishments or groups of establishments;
(v) the farming practices applied in the affected and neighbouring establishments and groups of establishments;
(vi) the hydrodynamic conditions; and
(vii) other factors of epidemiological significance identified;
(b) the geographical demarcation must comply with the following minimum requirements:
(i) the protection zone must consist of an area included in a circle with a radius of at least one tidal excursion or at least 5 km, whichever is larger, centred on the establishment infected with Bonamia ostreae, or an equivalent area determined according to appropriate hydrodynamic or epidemiological data; and
(ii) the surveillance zone must consist of an area surrounding the protection zone, of overlapping tidal excursion zones; or an area surrounding the protection zone and included in a circle of radius 10km from the centre of the protection zone; or an equivalent area determined according to appropriate hydrodynamic or epidemiological data;
or
(iii) where separate protection and surveillance zones are not established, the restricted zone must consist of an area comprising both the protection zone and the surveillance zone.
Table 5.A
Scheme for Member States, zones or compartments for the 3-year control period which precedes the achievement of status free from infection with Bonamia ostreae
Year of surveillance
Number of health visits per year to each establishment or group of establishments
Number of laboratory examinations per year
Number of molluscs in the sample
Year 1
1
1
150
Year 2
1
1
150
Year 3
1
1
150

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Source: https://www.legislation.gov.uk/eur/2020/689/annex/VI/chapter/5/section/3/division/2 (the official version)
Page: https://openlegislation.uk/eu-regulation-2020-689/annex-VI/chapter-5/section-3/division-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.