An independent working party has been created by
The Royal Society of Edinburgh (RSE) to assess the science behind legislation
governing the control of Infectious Salmon Anaemia (ISA). A viral disease
of salmon, but one which poses no threat to human health, the first
outbreak of ISA was detected in 1998 in a salmon farm in Loch Nevis.
To date it is known to have spread to 11 farms and has been suspected
on a further 25 farms on the Scottish West Coast; in Skye, Orkney, Shetland
and the Western Isles. Infection by the virus does not always lead to
severe clinical signs of the disease and the death of the fish, yet
current European legislation requires that once a fish farm has been
designated as infected, all fish will eventually have to be withdrawn,
the site disinfected and left fallow for 6 months. There is presently
no compensation for any income lost by farmers as a result of this process.
Concerns have been raised about the methods used to
identify and verify the presence of the virus in a farm. Fish which
have the virus do not necessarily show clinical signs at low levels
of infection. Doubts have also been expressed about the accuracy of
the viral test methods and the risk of false positive results.
Sir Roderick MacSween, Chairman of the Working
party said:
We wish to examine the evidence for ISA being
an exotic and not an endemic infection in salmon in Scotland. In addition
the scientific basis for establishing viral infection and confirming
the presence of virus-related disease must be shown to be robust:
implementation of the withdrawal proposal when viral infection is
suspected has serious consequences for farmers and, even more significantly,
for those breeding salmon stock.
Sir William Stewart, President of The Royal
Society of Edinburgh said:
Scotland’s Salmon farming industry is
hugely important to our economy. As a nation, we must protect and
conserve our environment and our natural resources. This is a complex
issue for the environmentalist, for business and for local communities.
The RSE has been asked to address this issue and Council has agreed
to do so. Our in-depth inquiry must be focused on the science underpinning
this issue and advice must be wholly independent and scientifically
robust. I am most grateful to Sir Roderick MacSween for agreeing to
chair this group. He is a distinguished and experienced chairman and
I am confident that he and his team will provide a thorough and detailed
analysis of the issue.
The remit of the RSE’s working party
is to investigate:
- the scientific issues surrounding the scheme submitted
by the United Kingdom for the withdrawal of all fish in Scottish farms
infected with infectious salmon anaemia (ISA), required under EU Directive
2000/27/EC(2)
- the reliability of detection methods
- the effectiveness of culling as a means of control,
making use of comparisons with regimes for control in other countries
- the prevalence/incidence and nature of ISA virus
in wild and farmed salmon.
The working party is being set up following representations
made to the RSE by members of the industry, expressing the view that
the current EC legislation is not based on science. The independent
group aims to report on its findings to the Council of the RSE by February
2002 and to publish its conclusions widely.
The membership of the Working Party is:
Chair - Sir Roderick MacSween
FRSE: Emeritus Professor of Pathology, University of Glasgow
Members - Professor Ian Aitken:
Scientific Director, Edinburgh Centre for Rural Research
Professor Peter Maitland FRSE: Independent
Research Consultant, Fish Conservation Centre
Professor Imants Priede FRSE: Professor
of Zoology, University of Aberdeen
Professor Stuart Reid FRSE: Professor
of Comparative Epidemiology and Informatics, University of Glasgow Veterinary
School
Professor John Sargent FRSE: Professor
of Marine Biochemistry, Institute of Acquaculture, University of Stirling
Sir William Stewart: FRS FRSE: President
of the RSE
Secretary - Dr
Marc Rands: Research Officer, Royal Society of Edinburgh
Background Information on ISA
| 1. |
Infectious Salmon Anaemia (ISA) is a viral disease that affects
Atlantic salmon (Salmo salar) but poses no threat to human health. |
| ISA in Scotland |
| 2. |
ISA had been identified in Norway (1984) and Canada (1997) but
was thought to be exotic to the European Union before 1998, when
it was discovered in a salmon farm in Loch Nevis. To date it has
spread to a total of 11 farms and has been suspected on a further
25 farms on the Scottish west coast, Skye, Orkney, Shetland and
the Western Isles. All 11 confirmed sites and almost all the 25
sites which were suspect are now back in production after fallowing. |
| European Legislation concerning ISA and the
outbreak in Scotland |
| 3. |
In 1991 ISA was classified as a List 1 disease (Council Directive
91/67/EEC (as amended)), which is required to be eradicated under
European legislation through control measures initially prescribed
in Council Directive 93/53/EEC (see Appendix 1). These control measures
required the immediate withdrawal of fish from an infected farm,
where official confirmation of infection by laboratory examination
or clinical and post-mortem examination had taken place. |
| 4. |
Following the outbreak in Scotland in 1998, the European Commission
developed proposals for a more pragmatic way to control ISA to allow
efficient control of the disease whilst safeguarding as much as
possible the interests of the infected sites. These amendments to
Council Directive 93/53/EEC, in addition to introducing the possibility
for vaccination against the disease, spread the obligation to empty
affected fish farms over a period of time (rather than immediately),
subject to a withdrawal scheme which required approval by the European
Commission. This was to take into account the particular circumstances
on the affected site, including fish welfare considerations. For
example, a remote farm with low mortalities or few clinical signs
in the fish might be allowed a cage by cage clearance programme
based on mortality triggers. On the other hand, an infected farm
close to other uninfected farms and suffering high mortalities would
be required to clear as soon as possible. |
| 5. |
In May 2000 the European Commission carried out a Mission to Scotland
to assess the situation following the ISA outbreaks. Their report
in August 2000, recommended to the Scottish authorities that they
should reconsider the decision-making processes for the confirmation
of infection by ISA virus, with virus isolation in cell culture
leading to confirmation of the infection, regardless of the state
of disease on a farm. At that time the procedure adopted for diagnosis
of ISA in Scotland, supported by the Final Report of the Joint Government/Industry
Working Group on Infectious Salmon Anaemia in Scotland (2000), was
that in adopting Council Directive 93/53/EEC, all of the following
criteria needed to be satisfied to confirm the presence of ISA:
clinical disease, typical macroscopic findings including evidence
of anaemia, typical histological findings and evidence of infection. |
| 6. |
In May 2001 the European Commission accepted a withdrawal scheme
submitted by the UK (Scotland), in response to the European Commission
amendment to Council Directive 93/53/EEC, requiring the development
and approval of a withdrawal scheme for fish in Scottish farms infected
with ISA (Commission Decision 2001/186/EC). |
| 7. |
In this UK (Scotland) scheme, the diagnosis of ISA would now reflect
the Mission to Scotland opinion that the presence of ISA would be
confirmed by either the isolation and identification of the ISA
virus from any fish on the farm, or the presence of clinical signs
and supportive laboratory tests (as described in the original Council
Directive 93/53/EEC). However, where no recent mortalities or fish
showing clinical signs of ISA were observed, no samples would be
required. If weak or abnormally behaving fish were observed, but
the clinical signs of ISA were not observed, however, samples could
be taken at the inspector’s or veterinarian’s discretion.
When ISA was detected (either by the isolation and identification
of the ISA virus from any fish on the farm or the presence of clinical
signs and supportive laboratory tests) the following factors would
be taken into account in determining the appropriate process of
withdrawal (note: in all cases restocking would not be allowed until
the farm had been fallowed for 6 months): |
| |
- the number of mortalities
- their distribution across the farm
- the rate at which mortality occurs
- cause of mortalities
- risks to neighbouring farms in the same water catchment area
or coastal zone
|
| 8. |
In the case of widespread mortalities, the farm would be required
to immediately begin the process of withdrawal and disposal of all
fish. However, in farms where there were no widespread mortalities,
fish would only be required to be withdrawn from parts of the farm
(i.e. cage, tank or pool) in which mortality had reached 0.05% of
the fish contained per day. Nevertheless, withdrawal in accordance
with this scheme would be intended to proceed in stages until the
farm had been cleared of fish. |
| 9. |
On the 21 June 2001, Council Decision 2001/186/EC (regarding the
Scottish withdrawal scheme) was amended to include England, Scotland
and Wales. |
| Scottish Executive Legislation concerning
ISA |
| 10. |
In Scotland, Council Directive 91/67/EEC is implemented in the
UK through The Diseases of Fish (Control) Regulation 1994. |
| 11. |
A new Code of Practice on Infectious Salmon Anaemia was produced
in August 2000 to avoid and minimise the impact of Infectious Salmon
Anaemia, arising from the Joint Government/Industry Working Group
on ISA, including the possibility of a range of biological vectors
of ISA. |
| 12. |
A report into the cause of the outbreak of ISA in 1998 was published
by the Fisheries Research Services in April 2001. The report was
unable to identify the origin of the outbreak; however it was narrowed
down to either the virus being introduced accidentally on a well
boat from infected areas in Norway, or from a wild reservoir. |
| Industry Concerns |
| 13. |
Concerns have been raised about the impact on the Scottish salmon
industry of the scheme categorising a farm as having the disease,
when evidence for infection has been based on the isolation and
identification of the ISA virus from any fish on the farm, without
any clinical signs of the disease. In particular concerns have been
raised about the accuracy of the viral test methods (and risk of
false positive results), and the prevalence of the virus in the
wild with the possibility of routine viral infection of farmed fish
from wild populations at levels which don’t cause the harmful
clinical disease. Once a farm has been designated as infected, all
fish will eventually have to be withdrawn and the site disinfected
and left fallow for 6 months. There is, however, no compensation
for any lost income by farmers as a result of this process. |
| 14. |
Following an outbreak of ISA in May 1998, the Scottish Office,
in September 1999 introduced a fund of up to £9 million over
three years to provide assistance to individual farmers who face
losses caused by ISA. This was approved by the European Commission
on 30 May 2000 and was to be administered by Highlands and Islands
Enterprise. |
| 15. |
On 23 June 2000 the European Parliament noted that they were of
the opinion that the Scottish salmon industry faced an ongoing crisis
which would become more severe if no remedial action was taken.
It called for the addition of ISA in the list of diseases provided
for by Council Decision 90/924/EEC and for funding to be provided
for research into a vaccine against ISA. |
| 16. |
On 16 November 2000 the Scottish Parliament European Committee
asked the Scottish Executive and European Commission to re-examine
financial support for salmon farmers and to reclassify the types
of fish disease which qualify for funding assistance under Decision
90/424, and to explain why Norway does not follow the regime imposed
on Scotland and the rest of the EU. |
| 17. |
On 21 September 2001 the advocate general of the European Court
of Justice gave the opinion that salmon farmers had no right to
compensation for fish slaughtered during the outbreak of infectious
salmon anaemia in the late 1990s. The case was brought against the
Scottish Executive by the fish farming companies Hydro Seafood and
Marine Harvest. It is now up to the full court to decide whether
to accept this view. |
| |
|
Notes for Editors
1. Sir Roderick MacSween, Chairman of the Working
Party is Emeritus Professor of Pathology at The University of Glasgow.
He is a past President of The Royal College of Pathologists and was
Chairman of The Academy of Medical Royal Colleges. Sir Roderick is married,
with two children and one grandson. |
