zone

(a) for terrestrial animals, an area of a Member State, third country or territory with a precise geographical delimitation, containing an animal subpopulation with a distinct health status with respect to a specific disease or specific diseases subject to appropriate surveillance, disease control and biosecurity measures; (b) for aquatic animals, a contiguous hydrological system with a distinct health status with respect to a specific disease or specific diseases that forms an area that is referred to in one of the following: (i) an entire water catchment from the source of a waterway to the estuary or lake; (ii) more than one water catchment; (iii) part of a water catchment from the source of a waterway to a barrier that prevents the introduction of a specific disease or diseases; (iv) part of a coastal area with a precise geographical delimitation; (v) an estuary with a precise geographical delimitation;