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

Fishery

Methods

Potential effects

Demersal fin fish

Gill netting

  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.

Salmon farming

Fish cage

  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 populations.

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