Seals

Status of harbour (common) seals and grey seals: Stable with some concerns 

(Baxter, et al. 2011)

Status of seals: Improving since 2012 

(United Kingdom Marine Monitoring & Assessment Strategy, n.d)

The Atlantic grey seal (Halichoerus grypus) and the harbour (common) seal (Phoca vitulina) are found around the UK, and both present in the Solway Firth.

Seal types are often difficult to distinguish, however the head is often a good way to tell them apart. Harbour seals are snub-nosed with V-shaped nostrils, whilst greys have elongated ‘horse-head’ muzzles, which are convex in males giving them a ‘Roman’ nose.

Size can be deceptive depending on if the seal is on its own and underwater. Harbour seals are the smaller of the two seal species found in the Solway, weighing between 75 and 85kg. Grey seals are much heavier with females weighing up to 180kg and males up to 300kg (NatureScot, n.d.).

Image; Grey seal pup. © N. Coombey/ Solway Firth Partnership

Seals

Seals in the Solway

According to NatureScot (NS) there are roughly 100,000 harbour seals in Europe, with ~30% of this population in UK waters, and 80% of the UK population located within Scottish waters (NatureScot, n.d.).

Scottish waters similarly support the vast majority of the UK’s grey seal population. 90% of the UK’s grey seal population can be found in Scotland, which is around 144,000 (based on a UK population of ~160,000). This is a significant portion of the World’s grey seal population, which is a rarer species than the harbour seal, with around 400,000 individuals worldwide (NatureScot, n.d.).

The Solway Firth and the eastern Irish Sea as a whole supports small numbers of both harbour and grey seals and does not make any significant contribution to either the UK harbour or grey seal populations.

Shetland and Orkney are particularly popular areas for both types of seal, and the abundance of both seals is greater further north on the West coast of Scotland than the Solway.

The Sea Mammal Research Unit (SMRU) aims to conduct aerial surveys of seal numbers in Scotland on a five year cycle, with surveys being conducted each August. This is when the most consistent harbour seal numbers can be assessed as it is during their annual moult, for which harbour seals are hauled ashore. Grey seal numbers seen ashore are also assessed at the same time. 

The data collected through these surveys ‘…provide the basis of the information the Natural Environment Research Council is obliged to submit to the Scottish Government and to the Department for Environment, Food and Rural Affairs (Defra) under the Marine (Scotland) Act 2010 and the Conservation of Seals Act 1970 respectively, on the size, distribution and status of UK seal populations…The surveys also provide information required by NatureScot to satisfy Scottish obligations under the [EC]’s Habitats Directive on reporting the conservation status of seals within Special Areas of Conservation (SACs) and in Scotland.’ (Duck & Morris, 2016)

Comparing surveys over time suggests that seal numbers within the Southwest Scotland Seal Management Area are overall stable, not declining as they are in other management areas, such as harbour seals in Shetland and Orkney within the same time period.

The Solway falls into the Southwest Scotland Seal Management Unit which includes the Clyde. Of the seven designated haul-out sites within this Seal Management Area two sites lie within the Scottish side of the Solway. These are designated under the Marine (Scotland) Act 2010 and The Protection of Seals (Designation of Haul-Out Sites) (Scotland) Order 2014. These sites are; Little Scares and Solway Firth outer sandbank. There are a total of 194 haul-out sites in Scotland.

Harbour Seals;

Table Source; Duck & Morris 2016

Grey Seals;

Table Source; Duck & Morris 2016

According to several sources, including the original 1996 Solway Review, and local knowledge, Mullock Bay is known to be one of the regular haul-out sites for grey seals, however, there is no designation for this site. Despite the lack of designation this beach is locally known as a popular site for sighting grey seals in particular. Images submitted as part of the Solway Photo Series shows seals in Mullock Bay. Similarly, locals suggest that North Cairn has a haul-out site where at least two dozen grey seals can be spotted, but also has no official designation. Seals Cave on the Mull of Galloway is known for people canoeing to see the seals.

Occasionally, harbour seals are recorded using rock or shingle haul-out sites on the Cumbrian coast and on sand banks in the Solway Firth. However, total numbers counted are less than 10 animals, and therefore the focus is on the Scottish side of the Solway. 

According to Scotland’s Marine Assessment, grey seal summer abundance has remained stable in the Southwest Scotland Seal Management Unit, however between 2008 and 2014 there appears to be a reduction in the grey seal abundance in the inner Solway, which was estimated ~50 grey seals (by 10km square) in 2008 and (appears to be) none in 2014 (Moffat et al, 2020). In the whole Southwest management unit there was no difference between the number of grey seals counted in 2008 and 2014, although it is important to remember that this includes the Clyde where seals are more abundant (Moffat et al, 2020).

Image; Seal haul-out. © N. Coombey/ Solway Firth Partnership

Seals

Pressures

There are many pressures which may impact the numbers of seals seen in the Solway and in the wider UK. The assessment of the threats to seal numbers has been limited to potential and real threats to the Solway Firth seal populations. Common predators of harbour and grey seals are not known to be present in the Solway Firth and therefore are not discussed here.

Threats include;

• Death by humans
  • Details on the rules surrounding the killing of seals will be explored in the following section on conservation status of seals.
  • Although this is a potential threat it is a limited threat in the Solway.
• ‘Corkscrew’ lesions
  • Deceased seals with ‘corkscrew’ lesions have previously been thought to be victims of shark attacks or vessel propellers. However, recently a paper has presented evidence that these injuries may have actually be a result of infanticide and cannibalism caused by other seals (Brownlow et al, 2016).

• Excessive pollution
  • Pups are highly at risk from physical contamination from oil spills
  • Nurdles are now common on beaches known to be haul-out sites. These nurdles can make their way into the food chain of seals. Pollution in the form of plastics can cause harm to seals by trapping or causing injury.
• Harmful Algal Toxins
  • Harmful algal blooms can release toxins and contribute to the deaths of marine mammals such as seals through eating contaminated prey.
  • This can happen in the UK through;
    • Domoic Acid – responsible for Amnesic Shellfish Poisoning (ASP)
    • Saxitoxins – responsible for Paralytic Shellfish Poisoning (PSP)
  • As these toxins are causes of shellfish poisoning in shellfish intended for human consumption monitoring is required under Regulation (EC) No 854/2004 of the European Parliament
  • Food Standards Scotland is required to monitor areas of shellfish harvesting in Scotland.
  • 4 weekly reports for the Scottish monitoring sites are available here, including two representative monitoring sites in Dumfries and Galloway.
  • The Centre for Environment, Fisheries and Aquaculture (Cefas) is responsible for testing for PSP & ASP toxins, among others, in England on behalf of the competent authority.
  • The sampling plan for Lees Scar, the only site currently monitored in the English Solway, is available here. 
• Toxic chemicals
  • When ingested, chemicals build up in the blubber and can be passed along to pups through mother’s milk. PCBs (Polychlorinated Biphenyls), banned in 1979, and DDT (Dichlorodiphenyltrichloroethane), banned in 1986, are still present within our ecosystem and could cause damage to seals.
• Fishing nets
  • Seals may become entangled in fishing gear, whether in use or disposed of, causing injury or death.
• Shipping and collision risk
  • Compared to other sections of Scotland’s marine area, the Solway Firth has relatively limited shipping and vessel traffic. The main areas of vessel traffic are in the vicinity of Cairnryan and Port of Workington, with other areas such as Kirkcudbright Harbour also having vessel traffic. As such shipping and collision risk is limited in the Solway, however is still a potential threat for seals.
• Marine renewable installations
  • Noise from construction of marine renewable sites can cause disturbance and damage to seals. A study of disturbance to harbour seals during construction in England did not find avoidance by seals during general construction, apart from during pile driving. Pile driving saw disturbance within a 25km radius and returned to pre-disturbance levels within 2 hours of this activity ceasing (Russel et al, 2016).
  • However, once constructed wind farms may help create hunting grounds for seals.
  • The construction and operation of wind turbines will create increased vessel density around the area for the construction phase and maintenance once operational. Increased vessel traffic does increase the risk of collision and shipping risk to seals.
  • Interactions with tidal and wave renewable instillations are not included here, as neither of these types of instillations are in place in the Solway at present. For information on these instillations and interactions with seals please see the 2017 SMRU scientific advice paper.
• Climate change
  • Changes in the climate will likely cause changes in distribution of seals prey and the availability of prey, however the degree of change which will be seen in prey is unknown and depends on the progression of climate change.
• Disease
  • Phocine distemper virus devastated harbour seal populations in 1988 in the North, Irish and Baltic seas. The virus killed around 18,000 harbour seals and potentially hundreds of grey seals. A similar outbreak occurred in 2002 (Duignan, et al, 2014). These outbreaks led to the death of 50% of eastern England’s harbour seal population in 1988, and 22% in 2002  (Duck, 2010). The virus could significantly harm the harbour seal population of the Solway should an outbreak happen in the region.

Seal Stranding Data in the Solway;

Table data; Information for this table was gathered from the National Marine Plan Interactive (2019), data layer ‘Marine standings data 2013 – 2018 (cetaceans, seals, sharks, turtles) (time-aware)‘ with data provided by Scottish Marine Animal Strandings Scheme (SMASS).

Additional stranding data;

Scottish Marine Animal Stranding Scheme (SMASS) has an interactive map which can provide information on stranding from 1991 until 2018 along the entire Scottish coast. If seeking additional strandings data on seals or other marine animals please click here to link to the SMASS interactive map.

Image; Grey seal pup. © N. Coombey/ Solway Firth Partnership

Seals

Conservation status

The EU Marine Strategy Framework Directive (MSFD) seeks to achieve ‘Good Environmental Status’ (GEnvS) across European member states marine areas by 2020. In terms of defining what GEnvS is and how to reach it, there are 11 qualitative ‘descriptors’ included in Annex I of the MSFD to help each member state interpret GEnvS and illustrate what a marine environment which has GEnvS looks like. The descriptors 1 and 4 cover ‘biological diversity’ and ‘Food webs’ respectively and in the UK multiple aspects of the marine environment are assessed as part of these two descriptors. Achieving GENvS in terms of ‘biological diversity’ is measured through assessing; cetaceans, seals, birds, fish, pelagic habitats, and benthic habitats. The GEnvS of ‘food webs’ uses assessments off; cetaceans, seals, birds, fish, and pelagic habitats. The UK’s updated Part 1 Assessment, published in 2019, sets out progress towards GEnvS and reviewed progress for Scottish and English waters. Indicators cover population size and condition in relation to both grey and harbour seals in addition to grey seal pup production. The UK has reached its targets for grey seals in seeking GEnvS in the Celtic Seas, with the status of harbour seals within the Celtic Sea being ‘uncertain‘ despite a significant increase in the abundance of harbour seals in West Scotland (United Kingdom Marine Monitoring & Assessment Strategy, n.d). In terms of GEnvS for descriptor 4, food webs, which seal assessments contribute too, the status of GEnvS was ‘uncertain’ in 2019. 

Both seal species are Priority Marine Features in Scotland, the harbour seal is also a UK Biodiversity Action Plan (UK BAP) priority marine species, and is a Feature of Conservation Interest, which are rare/threatened species or habitats used to help identify Marine Conservation Zones (MCZs) in England (for MCZs in the Solway see Protected Areas). The UK BAP has now been succeeded by the ‘UK Post-2010 Biodiversity Framework‘, published in July 2012. Despite this, the UK BAP lists of priority species and habitats are invaluable for Scotland and England when drawing up their own biodiversity lists. From the basis of the UK BAP the harbour seal appears on the Scottish Biodiversity list as requiring conservation action and the English list of Species of Principal Importance. These statutory lists of important species are required under s.41 of the Natural Environment and Rural Communities Act 2006 in England, and s.2(4) of the Nature Conservation (Scotland) Act 2004 in Scotland.

In accordance with the EC Habitats Directive harbour and grey seals are two of the approximately 900 animal or plant species in Annex II ‘whose conservation requires the designation of Special Areas of Conservation’ (SACs).

Seal Conservation Areas (SCAs) have also been introduced for harbour seals in Scotland through the Marine (Scotland) Act 2010. There are no seal SACs (seals are not a qualifying interest for which Luce Bay and Sands SAC, or the Solway Firth SAC were designated) or SCAs in the Solway Firth.

The Conservation of Seals Act 1970 and the Conservation of Habitats and Species Regulations 2017 limit the killing of seals in England to certain times of the year and in certain ways, and the Marine (Scotland) Act 2010 prohibits killing seals entirely at any time.

In England seals are only permitted to be killed in certain ways and during certain times of the year. Grey seals are not to be killed from 1st September to 31st December and 1st June to 31st August for harbour seals. These are known as the ‘closed season’. All seals are protected from unauthorised methods of killing.

Previously there was an exception allowing anyone to control individual seals during the closed season or in a conservation order area to prevent damage to their fishing nets, tackle or catch known as the ‘netsman’s defence’, under section 9 of the Conservation of Seals Act 1970. This is no longer a defence, and was removed from legislation as of March 2021. 

In Scotland, killing seals at any time is an offence. Shooting seals is permitted under licence as an exception to the offence of killing a seal according to the Marine (Scotland) Act 2010. Preventing damage to fish farms and the protection of the health and welfare of farmed fish are two of the circumstances under which Scottish Ministers are permitted to grant a ‘seal licence‘.

As of 31st January 2019 there were 4 seal licences granted in South-West Scotland seal management area (which the Scottish Solway forms part of) giving permission to shoot a total of 12 grey seals, and 13 harbour seals. The numbers of seals permitted to be shot with licences change on an annual basis as a result of seal population numbers and trends. Although throughout 2019, 1 common/harbour seal and 2 grey seals were shot throughout the South-west Scotland seal management area (Marine Scotland, 2019). In 2020, 4 licenses were granted again, this time for 11 grey seals, and 12 harbour seals. As of mid-2020, 5 grey seals and 7 harbour seals had been shot in the South-west Scotland region (Marine Scotland, 2020).

Information about seal licences and shot seals is updated frequently. The most up-to-date information and information from previous years (2011 onwards) is available here.

Haul-out sites are areas where seals emerge from the water onto land to rest, breed, and moult. An offence relating to haul-out sites was created under s.117 of the Marine (Scotland) Act 2010, making it an offence to intentionally or recklessly harass seals at these sites. These sites are designated through The Protection of Seals (Designation of Haul-out Sites) (Scotland) Order 2014, which provides the coordinates of 4 points for each designated site outlining the sites exact location and area. The Solway has two designated sites; Little Scares & Solway Firth Outer Sandbank.

Guidance on what is considered ‘harassment’, ‘intentional’, and ‘reckless’ can be found in the Guidance on the Offence of Harassment at Seal Haul-out Sites, published by Marine Scotland in 2014.

Both the grey seal and the harbour seal are on the International Union for Conservation of Nature (IUCN) red list of threatened species. Both the grey and harbour seal are considered to be of ‘least concern’ on the scale of how threatened species are. Populations were last globally assessed in 2016 by the IUCN with the population trend for the grey seal increasing. Despite the harbour seal being listed as an IUCN ‘least concern’ species it must be noted that this does not reflect the finer scale monitoring of harbour seals, where some populations have recently been in significant decline.

The map seen on the page opposite illustrates the limited numbers of both grey and harbour seals surveyed in the Solway, along with the two designated haul-out sites within the Solway limits.

Image; Scotland’s National Marine Plan Interactive, with layers (links will provide usage licence, data provider, etc); ‘Solway Region (mask)‘ © Crown Copyright, All rights reserved, Designated haul-out sites for Grey and Common/Harbour Seals (Protection of Seals Orders) – May 2017 (OSCP) © Crown Copyright, All rights reserved, Contains information from Scottish Government (Marine Scotland) & Sea Mammal Research Unit (SMRU) licensed under the Open Government Licence v3.0, Seals – SMRU coordinated summer counts of Grey seals (Halichoerus grypus) in period 2011 to 2015 (SNH WMS) © Crown Copyright, All rights reserved, and Seals – SMRU coordinated summer counts of Common/Harbour seals (Phoca vitulina) in period 2011 to 2015 (SNH WMS) © Crown Copyright, All rights reserved

Seals

References

Arso Civil, M., Smout, S.C., Duck, C., Morris, C., Cummings, C., Langley, I., Law, A., Morton, C., Brownlow, A., Davison, N., Doeschate, M., Lacaze, J-P., McConnell, B., and Hall, A.J. (2018). Harbour Seal Decline –vital rates and drivers. Report to Scottish Government HSD2. Sea Mammal Research Unit, University of St Andrews, pp. 63. Available here. (Accessed: 25.11.19)

Hall, A.J. & Thomas, G.O. (2007). Polychlorinated biphenyls, DDT, polybrominated diphenyl ethers and organic pesticides in United Kingdom harbor seals – mixed exposures and thyroid homeostasis. Environmental Toxicology Chemistry, 26(5), 851- 861.

Joint Nature Conservation Committee and Department of Environment, Food and Rural Affairs (on behalf of the Four Countries’ Biodiversity Group). (2012). UK Post-2010 Biodiversity Framework. Available here. (Accessed: 07.07.18)

Joint Nature Conservation Committee (2007). Report on the Species and Habitat Review (UK BAP) Available here. (Accessed: 07.03.18)

Joint Nature Conservation Committee (2007). UK Biodiversity Action Plan Priority Marine Species. Available here. (Accessed: 07.03.18)

Joint Nature Conservation Committee (1994). UK Biodiversity Action Plan. Available here. (Accessed: 27.11.19)

Lowry, L. (2016). Phoca vitulina. The IUCN Red List of Threatened Species 2016: e.T17013A45229114. Available here. (Accessed: 25.11.19)

Marine Life Information Network (n.d.). Species listed as Features of Conservation Interest (FOCI). Available here. (Accessed: 14.05.20)

Marine Life Information Network (n.d.). Species listed as ‘species of principal importance’. Available here. (Accessed: 14.05.20)

Marine Management Organisation. (n.d.). Marine Planning Evidence Base. Available here. (Accessed: 14.05.18)

Marine Scotland (n.d.). Scotland’s National Marine Plan Interactive. Available here. (Accessed: 06.08.19)

Marine Scotland (2014). Guidance on the Offence of Harassment at Seal Haul-out Sites. Available here. (Accessed: 12.11.19)

Mills, F., Sheridan, S. and Brown S., (2017). Clyde Marine Region Assessment. Clyde Marine Planning Partnership. pp 231, Available here. (Accessed: 14.05.18)

NatureScot (2020). Priority Marine Features in Scotland’s Seas. Available here. (Accessed: 04.05.21)

NatureScot (2020). Scottish Biodiversity List. Available here. (Accessed: 04.05.21)

Scottish Government (2014). Guidance on Haul-Outs. Available here. (Accessed: 09.01.20)

Scottish Marine Animal Stranding Scheme (n.d.). Interactive map database of Strandings. Available here. (Accessed: 17.12.19)

Sea Mammal Research Unit (2018). Special Committee on Seals, Scientific Advice on Matters Related to the Management of Seal Populations: 2018. Available here. (Accessed: 11.11.19)

Sea Mammal Research Unit Reports (n.d.). Available here. (Accessed: 13.06.18)

Solway Firth Partnership (1996). The Solway Firth Review, Solway Firth Partnership, Dumfries. Available here. (Accessed: 23.07.19)

South West Scotland Environment Information Centre (n.d.). Marine Mammals. Available here. (Accessed: 11.11.19)

UK National Ecosystem Assessment (2011). The UK National Ecosystem Assessment Technical Report. UNEP-WCMC, Cambridge. Available here. (Accessed: 28.05.18)

In-Text References;

Baxter, J.M., Boyd, I.L., Cox, M., Donald, A.E., Malcolm, S.J., Miles, H., Miller, B., Moffat, C.F., (Editors), (2011). Scotland’s Marine Atlas: Information for the national marine plan. Marine Scotland, Edinburgh. pp 191. Available here. (Accessed: 22.07.19)

Brownlow, A., Onoufriou, J., Bishop, A., Davison, N., & Thompson, D. (2016). Corkscrew seals: grey seal (Halichoerus grypus) infanticide and cannibalism may indicate the cause of spiral lacerations in seals. PloS one, 11(6), e0156464. Available here. (Accessed: 26.11.19)

Department for Environment Food & Rural Affairs (2019). Marine Strategy Part One: UK updated assessment and Good Environmental Status. Available here. (Accessed: 10.01.21)

Duck, C.D. (2010). Charting Progress 2 Healthy and Biological Diverse Seas Feeder Report: Section 3.5: Seals. Published by Department for Environment Food and Rural Affairs on behalf of UKMMAS. p506-539. In: UKMMAS (2010) Charting Progress 2 Healthy and Biological Diverse Seas Feeder Report (Eds. Frost, M & Hawkridge, J). Available here. (Accessed: 27.11.19)

Duck, C.D. & Morris, C.D. (2016). Surveys of harbour and grey seals on the south-east (border to Aberlady Bay) and south-west (Sound of Jura to Solway Firth) coasts of Scotland, in Shetland, in the Moray Firth and in the Firth of Tay in August 2015. NatureScot Commissioned Report No. 929. Available here. (Accessed: 11.11.19)

Duignan, P. J., Van Bressem, M. F., Baker, J. D., Barbieri, M., Colegrove, K. M., De Guise, S., De Swart, R. L., Di Guardo, G., Dobson, A., Duprex, W. P., Early, G., Fauquier, D., Goldstein, T., Goodman, S. J., Grenfell, B., Groch, K. R., Gulland, F., Hall, A., Jensen, B. A., Lamy, K., Matassa, K., Mazzariol, S., Morris, S. M., Nielsen, O., Rotstein, D., Rowles, T. K., Saliki, J. T., Siebert, U., Waltzek, T., & Wellehan, J. F. X. (2014). Phocine distemper virus: Current knowledge and future directions. Viruses, 6(12), 5093-5134. Available here. (Accessed: 12.11.19)

Marine Scotland (2020). ‘Seal Licensing’ Marine Scotland Website. Available here. (Accessed: 12.11.20)

Marine Scotland (2019). ‘Seal Licensing’ Marine Scotland Website. Available here. (Accessed: 25.11.19)

Moffat, C., Baxter, J., Berx, B., Bosley, K., Boulcott, P., Cox, M., Cruickshank, L., Gillham, K., Haynes, V., Roberts, A., Vaughan, D., & Webster, L. (Eds.). (2020). Scotland’s Marine Assessment 2020. Scottish Government. Available here. (Accessed: 10.04.21)

National Marine Plan Interactive (2019) Data layer Number 852; ‘Marine standings data 2013 – 2018 (cetaceans, seals, sharks, turtles) (time-aware)’ with data provided by Scottish Marine Animal Strandings Scheme (SMASS). Available here. (Accessed: 16.12.19)

NatureScot (n.d.) Seals. Available here. (Accessed: 11.11.19)

Russell, D.J.F., Hastie, G.D., Thompson, D., Janik, V.M., Hammond, P.S., Scott-Hayward, L.A.S., Matthiopoulos, J., Jones, E. L. & McConnell, B. J. (2016). Avoidance of wind farms by harbour seals is limited to pile driving activities. Journal of Applied Ecology, 53, 1642-1652. Available here. (Accessed: 11.11.19)

United Kingdom Marine Monitoring & Assessment Strategy (n.d). Summary of Progress towards Good Environmental Status. Available here. (Accessed: 15.12.20)

Image; Grey seal pup. © N. Coombey/ Solway Firth Partnership