Grey seal (Halichoerus grupus) and common
seal (Phoca vitulina)
Candidate SACs for grey seal:
North Rona, Monach Islands, Pembrokeshire Islands,
Berwickshire & North Northumberland Coast, Faray
& Holm of Faray
Candidate SACs for common seal:
Mousa, Wash & North Norfolk Coast, Sanday.
The two species of seal found in UK waters (grey
seal and common seal) are both listed in Annex II
of the Habitats Directive. Grey seals tend to live
in rocky wave exposed sites and form large breeding
aggregations on land during autumn. The pups remain
on shore for 3-5 weeks. Although generally having
a coastal distribution, grey seals are known to
travel considerable distances. Common seals favour
more sheltered inshore areas, using islands and
sand banks as haul out sites. They tend to be more
localised than grey seals, staying in the same general
area to breed, feed and rest, and do not form as
large breeding colonies. The pups usually leave
the shore on the first high tide after birth.
Seals have been caught in mobile fishing gear but
in most cases they are associated with static gears.
Incidental catch of grey seals and common seals
in gill nets has been widely reported19,43.
Mortality of grey seals consistent with being entangled
in gill nets has been recorded and it has been suggested
that young seals are more likely to become caught
in this way10,19.
Mortality may also result from capture in anti-predator
nets set around salmon farms19,41,59.
Fish farm operators and fishermen are permitted
to shoot seals, under the Conservation of Seals
Act 1970, to prevent damage to their nets or any
fish within them. The impact of this is difficult
to assess but is probably localised and limited
in extent. Although it could have a significant
effect on local populations89, seal mortality
around fish farms and other fishery related mortality
has not had a deleterious effect on the seal population
in UK waters19,41.
Some of the studies looking at the effects of fisheries
on seals have information from areas in and around
European marine sites (Cardigan Bay10,
Farne Islands19, Orkney43)
but the more general studies, for example covering
the North Sea9,43, are also relevant
as this type of mortality can occur far from the
breeding and haul out sites which have been selected
as European marine sites. This is particularly the
case for grey seals where non-breeding adults have
been tracked more than many hundreds of kilometres
from capture sites. Common seals are more likely
to stay in the vicinity of breeding sites although
they can switch to other sites.
Summary of the potential effects of fisheries
on grey and common seal
Demersal fin fish
Accidental capture whilst foraging in
or around nets.
Legal shooting by fishermen to prevent
damage to nets or the fish within the
nets. This is likely to be localised and
limited in extent and has not had a deleterious
effect on UK seal populations.
Entanglement in anti-predator nets.
Legal shooting by fish farm operators
to prevent damage to nets or the fish
within the nets. This is likely to be
localised and limited in extent and has
not had a deleterious effect on UK seal