Division I.1 General requirements

Health inspections and, where appropriate, the sampling for laboratory examination shall be carried out in the period of the year when prevalence of the parasite in the F1constituent GB territory, zone or compartment is known to be maximal. When such data is not available, sampling shall be carried out just after the water temperature has exceeded 17 °C.

When molluscs are to be sampled in accordance with the requirements set out in Part 4, the following criteria shall apply:

1. (a)

   if Ostrea spp. and Mytilus spp. are present in the production units or production area, both genera shall be sampled equally in sample size. If only one of those genera is present, that genus shall be sampled. If neither Ostrea nor Mytilus genera are present, the sample must be representative of all other susceptible species present;

2. (b)

   if weak, gaping or freshly dead but not decomposed molluscs are present in the production units, such molluscs shall primarily be selected. If such molluscs are not present, the molluscs selected shall include the oldest healthy molluscs;

3. (c)

   when sampling in mollusc farms which utilise more than one water source for mollusc production, mollusc representing all water sources shall be included for sampling in such a way that all parts of the farm are proportionally represented in the sample;

4. (d)

   when sampling in mollusc farming areas, mollusc from a sufficient number of sampling points, shall be included in the sample in such a way that all parts of the mollusc farming area are proportionally represented in the sample. The main factors to be considered for the selection of these sampling points are previous sampling points where Marteilia refringens was detected, stocking density, water flows, presence of susceptible species, presence of vector species, bathymetry and management practices. Natural beds shall be included in the sampling.