Context
Sites of Special Scientific Interest (SSSIs) can be notified if
they include qualifying features under the fish criteria
outlined in section 2 and 3 of Chapter 16 'Freshwater and
Estuarine Fish' of the Guidelines for Selection of
Biological SSSIs. In Northern Ireland, ASSIs are
selected on a very similar basis – the Guidelines
for the Selection of Biological ASSIs in Northern Ireland is an
addendum to the SSSI guidelines rather than an
alternative.
There are very few water bodies in
Britain with natural fish communities, as many communities have
been distorted by introductions of non-native species and/or native
species from a previously restricted geographical range.
Therefore diversity does not provide a valid criterion for
selecting SSSIs. Only in exceptional circumstances e.g.
extreme isolation or high research potential will SSSIs be notified
on community grounds.
The criteria for site selection are
based on the need to conserve isolated populations and rare
species. Isolated populations include examples of ecotypic or
genetically distinctive fish populations worthy of conservation,
such as possible post-glacial relict races of brown trout Salmo
trutta in Scotland and Northern Ireland.
The breeding sites of certain
nationally rare species, including vendace Coregonus
albula, whitefish Coregonus lavaretus, allis shad
Alosa alosa, twaite shad Alosa fallax and burbot
Lota lota are also qualifying features, though the last is
now probably extinct. Certain breeding and spawning sites of
smelt Osmerus eperlanus, a nationally uncommon species,
also qualify for SSSI site notification.
Fish listed on Annex II of the
EC Habitats Directive, and thereby qualifying as features for the
selection of Special Areas of Conservation (SACs), are: Atlantic
salmon Salmo salar, sea lamprey Petromyzon
marinus, river lamprey Lampetra fluviatilis, brook
lamprey Lampetra planeri, spined loach Cobitis
taenia, bullhead Cottus gobio, allis shad Alosa
alosa and twaite shad Alosa fallax.
Interpretation
The range of fish species encountered around the UK reflects
the distribution of particular habitat types. In Scotland,
for example, the list of designated features is dominated by
salmonids (Arctic charr
Salvelinus alpinus, Atlantic
salmon
Salmo salar and whitefish (powan)
Coregonus
lavaretus), lamprey species (brook, river and sea) and smelt
(sparling
Osmerus eperlanus). English and Welsh
lists contain these salmonid and lamprey species, but also include
a variety of other fish species which are absent, or virtually
absent, from Scotland. These are allis shad
Alosa
alosa, twaite shad
Alosa fallax, spined loach
Cobitis taenia and bullhead
Cottus gobio.
Atlantic salmon and the unique brown trout assemblage of Lough
Melvin are the only fish species listed as designated features in
Northern Ireland.
Overall, 27% of assessments reported
are in favourable condition. This is the lowest level of
favourable condition reported for species features and is well
below the average for species features. It is also well below
the average for all features combined. 92% of the A/SSSI and
16% of the SAC features reported are favourable. A further
12% of the SAC features reported are unfavourable-recovering.
Shad
Three, from a total of 13, allis and twaite shad populations
designated, have been reported. One population is considered
to be favourable and two in unfavourable condition. A wide
range of management issues were highlighted, but chief amongst
these were agricultural operations and water quality. Given
their ecological similarities, the similarity in adverse
activities between these species is not surprising.
Lampreys
Four of the six populations of brook lamprey Lampetra
planeri designated have been reported: two in favourable
condition and two unfavourable. Issues requiring
consideration include agricultural operations, a lack of remedial
management and poor water quality. Three river lamprey
Lampetra fluviatilis populations, out of a total number of
seven, have been reported; only one population is considered to be
in favourable condition. No adverse activities were put
forward to help ascertain reasons for the apparent poor performance
of these populations. Of the 24 sea lamprey Petromyzon
marinus sites designated, 15 have been reported. Five of
these are considered to be in favourable condition and 10
unfavourable. The range of adverse activities which were
considered to be of relevance were relatively consistent.
Chief amongst these were water management and water quality,
although a wide range of other issues, such as agricultural
operations, invasive species and over-grazing were also
mentioned.
Loach
Spined loach appear to be in poor condition within the UK.
All four features reported are considered to be in unfavourable
condition. Water management and water quality are a major
issue for this species, although 'lack of remedial management' is
also listed as an adverse activity.
Bullhead
Bullhead populations, like spined
loach, appear to be under considerable threat. 13 populations
are considered to be in unfavourable condition, and one
(the River Camel) is partially destroyed. A wide
range of adverse activities have been identified for this species,
which reflects the number and distribution of these sites
throughout England and Wales. Water management and water
quality were mentioned as being a pressure in almost every site,
although riparian management, agricultural operations and forestry
are also important. Other adverse activities include the
presence of unspecified invasive species, lack of remedial
management, and recreational disturbance.
Whitefish
Only one whitefish population has been reported; in favourable
condition. The proximity of a ruffe Gymnocephalus
cernuus population to this site means that the whitefish is
under potential threat. There is also a potential threat in
the form of recreational disturbance by powerboat users.
Smelt
Smelt, also known as sparling, have been reported from two
Scottish sites. Both sites are considered to be in favourable
condition. However, these results should not be treated with
complacency, as smelt are predictable in their spawning behaviour,
are marketable as a commercial commodity and are incredibly simple
to catch. These factors mean that it is highly vulnerable to
overfishing and this activity could eliminate the population in any
given year. Furthermore, they are relatively weak
swimmers, so river engineering or agricultural operations which
reduce water quality could have a significant negative
impact.
Arctic charr
Five Arctic charr sites have been reported. All of the
sites are located in Scotland and four out of the five were
considered to be in favourable condition. The unfavourable
site is acidified and there seems to be little prospect of recovery
in the short to medium term. Pressures on these sites include
water management, water quality, poor fisheries management,
invasive species (such as the introduction of perch Perca
fluviatilis), and recreational disturbance. Gravel
extraction was considered to be an issue for one population where
the Arctic charr population spawns within inflowing streams.
Atlantic salmon
Twelve Atlantic salmon assessments
have been reported. Of these, 11 are unfavourable, and one
(the River Camel) partially destroyed. A wide range of
pressures have been identified for Atlantic salmon, ranging from
water management and water quality to fisheries management.
Riparian and in-stream management is also an issue and agricultural
operations (including over-grazing and under-grazing), forestry and
development works carried out under planning permission also
feature regularly. Aquaculture is known to be a pressure at
at least one Scottish site.
Assemblages
Only one fish assemblage has been
reported. This is a whitefish (powan)/Arctic charr
population. Both of these features have been reported as
being in favourable condition. It follows that the 'fish
assemblage' feature is also in favourable condition.