Surveillance of fish farms was conducted in accordance
with European Council directive 91/67/EEC (until superseded
by directive 2006/88/EC), which required the routine
testing of farm sites once every two years. In order to
maximise the likelihood of detecting the pathogen, this
1 Dealers that collect and move fish from a fishery to another fishery,
possibly via a holding site.
2 Supply retail premises with fish that will be sold to hobbyists. Fish
held by wholesalers are either imported or supplied by farms.
3 Supply fish to the public for stocking in tanks or ponds.
directive required surveillance to be conducted during the
high risk period for SVC disease, when water temperatures
were between 10 and 17 ◦C (Ahne et al., 2002). Active
surveillance was not conducted on fisheries, which were
only tested if mortality was reported, or they were known
to have received fish from (or be connected to) sites suspected
of having, or testing positive for SVC.