Issued: 17th March
SNH rescue endangered species in Harris
An operation involving the relocation of one of Scotland's most endangered species to a more stable river area,
was carried out last week at a location in the Isle of Harris.
Scotland holds half the world's population of freshwater pearl mussels, although there are only an estimated 61
breeding sites left in the country. The location in Harris is one of the most important sites for the species in
Scotland.
Up to two hundred freshwater pearl mussels were moved to a more stable location by staff from Scottish Natural
Heritage (SNH), together with environmental consultancy Young Associates. Over the winter months there have
been some heavy spates redepositing large banks of gravel and eroded peat into the river. This had resulted in
the re-routing of a highly dynamic natural river system, cutting off water flow in a secondary channel, thereby
threatening the mussels resident there with death by dehydration. SNH were alerted to the seriousness of the
situation by the concerned landowner.
Pearl mussels have full protection under Schedule 5 of the Wildlife and Countryside Act 1981, which was
strengthened further in the Nature Conservation (Scotland) Act 2004. It is now an offence to intentionally or
recklessly kill, injure, take or disturb the mussels or their habitat. It is also illegal to sell or advertise pearl
mussels for sale without a licence from the Scottish Executive. However, they continue to be at risk from illegal
collection activities.
Freshwater pearl mussels are amongst Scotland's rarest and most complex species and their presence is an
indicator of the health of our rivers. The species now has a Biodiversity Action Plan, which aims to develop
greater understanding of its habitat requirements and safeguard existing populations for the future.
Mark Macdonald/Andy Robinson area officer, Stornoway said: "We are pleased to be carrying out this
translocation project along with the pearl mussel specialists. Moving the stranded mussels is regarded as the
most appropriate, cheapest and easiest option to ensure their survival. Ongoing monitoring will need to take
place in order to assess the success of this work in the longer term. A report on the work undertaken will be
compiled to record the number and size of mussels translocated and identify the sites used for re-location."
Roddy MacMinn, SNH area officer who was involved in the moving of the fresh water pearl mussels said: "The
project should have a high chance of success - a check a few days later found that the moved mussels had
opened up (started to filter feed), a sign that they were happy in their new locations."
Despite full legal protection for the pearl mussel since 1998, cases of theft still continue. In addition to human
greed pearl mussels are hampered by slow reproductivity and the very specialised environments which they need
to exist. They can live for up to 100 years, only thrive in clean water and require the presence of wild salmon to
reproduce.
Ends.
Scottish Natural Heritage is the Scottish Executive's statutory advisor in respect to the conservation,
enhancement, enjoyment, understanding and sustainable use of the natural heritage.
For further information please contact Mairi Gillies, SNH Press and PR Office, Inverness, 01463 723134
For free colour photo of fresh water pearl mussles please also contact Mairi - Mairi.Gillies@snh.gov.uk 01463
723134 or 07834707221
Notes.
Protected under Schedule 5 of the UK Wildlife and Countryside Act (1981) and the Wildlife (Northern Ireland)
Order 1985, the freshwater pearl mussel is also listed on annexes II and V of the EU Habitats Directive and
Appendix III of the Bern Convention. Classified as a priority species by the UK Biodiversity Steering Group, a
national Species Action Plan has been prepared to encourage measures for its survival.
Originally widely distributed throughout Scotland, a comprehensive survey from 1996 to 1999 revealed that the
freshwater pearl mussel is now extinct in most of the lowlands and scarce everywhere except for a handful of
Highland rivers. If the present rates of extinction continue, it has been estimated that surviving Scottish
populations may only persist for a further 25 years. Up to half the world's known remaining populations with
active recruitment now occur in Scotland.
1
d:\533569398.doc
The early causes of decline were undoubtedly pearl fishing and industrial pollution. The current lack of
recruitment may be due to a number of factors, including increasing siltation and eutrophication of rivers. The
recent declines in stocks of migratory salmonid fish upon which the larvae are dependent are also giving cause
for concern. River engineering for hydro-schemes, flood defence purposes and fishery improvements continues
to pose a serious localised threat. Forestry operations, acidification, effluent from fish farms and chemical sheep
dip are further threats to the declining populations.
2
d:\533569398.doc