7.—(1) The Secretary of State must carry out surveillance at such premises and of such birds as he considers necessary—
(a)to detect the prevalence in different species of poultry of infection with avian influenza virus subtypes H5 and H7; and
(b)to assess the risk of the spread of influenza of avian origin by wild birds.
(2) The Secretary of State must give notice to the occupier of premises selected by him for the purposes of such a survey.