Code of good practice not followed in Shetland salmon disease outbreak Published: 20 April, 2009
The outbreak of Infectious Salmon Anaemia in Shetland this year may have been aggravated by a code of good practice for Scottish Finfish Aquaculture not being fully complied with, it has been claimed.
Charles Allan, group leader of the Fish Health Inspectorate based at the Marine Laboratory in Aberdeen, also revealed today that companies experienced difficulties in maintaining continuity of businesses when movement restrictions were served to control a serious notifiable disease in the whole management area.
And he said that although disposal routes were identified and available to handle routine production wastes, there was no immediately available method of disposal for large volumes of controlled fish waste.
On January 2, Infectious Salmon Anaemia (ISA) was confirmed on a salmon ongrowing site in Shetland, the first confirmation of ISA in Scotland since an earlier outbreak in 1998. The site in question had been visited for other purposes during December 2008 by staff from the Fisheries Research Services (now part of Marine Scotland) Fish Health Inspectorate. During that visit, moribund fish were observed and a routine diagnostic sample was taken. At that time it was not suspected that ISA was present nor were signs suggesting infection with ISA observed at post mortem. Laboratory results from tissue culture and polymerase chain reaction tests proved positive for ISA virus, leading to the confirmation, and suspicion of the presence of disease at two other sites which had been stocked with fish from the confirmed site.
These sites are located in southwest Shetland mainland, one of the most intensively farmed management areas in Scottish aquaculture, accounting for approximately 10 per cent of the farmed salmon produced in Scotland.
A total of 40 farms were in the area and movement restrictions were served on them all, controlling the movement of live and dead fish. In addition, the confirmed and suspect sites were placed under further restriction, with controls being placed on the movement of boats, equipment and personnel. A map, illustrating the extent of the control and surveillance zones is shown below.
According to Mr Allan, fish health inspectors were immediately sent to the area, to ensure that biosecurity requirements were being met, to collect information regarding fish populations held on sites within the area and to carry out surveillance of fish stocks to ascertain whether or not there was any evidence of the spread of the virus. Results from these initial investigations, and samples taken subsequently, resulted in two further sites being confirmed as suffering from the disease on January 30 and March 20.
All of the fish held on the confirmed and suspect sites have been withdrawn under official supervision in a biosecure manner, being harvested for human consumption and processed in approved facilities. Many had already been harvested prior to the confirmation of the presence of the disease in early January.
A full report regarding this outbreak will be produced in due course, said Mr Allan.