Sharks, skates and rays

Status of sharks, skates and rays: Deterioration with many concerns

(Baxter et al, 2011)

Elasmobranchs is the collective name for sharks, skates and rays, which are known for having cartilaginous skeletons instead of bone. They are a subclass of Chondrichthyes, with the other subclass being Holocephali. Many of these species are known for their slow reproductive and growth rates. This means recruitment rates are low and can make them vulnerable to overfishing as stocks are slow to recover. Data and information on the elasmobranchs populations of the Solway Firth is limited, with information provided being on a broader scale covering a much larger area than the Solway. The Solway provides important nursery grounds for skates and rays through sub-tidal sand and gravel.

Image; Thornback Ray egg case otherwise known as ‘Mermaid’s purse’. © N. Coombey.

Sharks, skates and rays

Key species of the Solway Firth & Presence

According to the data within Scotland’s Marine Atlas (Baxter et al, 2011) several species of elasmobranchs are known to be present in the Solway Firth. This is not an exhaustive list of all species in the Solway and is based on those which are included in Scotland’s list of Priority Marine Features (PMF), with the addition of Tope sharks as they are often caught recreationally in the Solway. It is worth noting that Blue Sharks are a PMF according to Scotland’s Marine Atlas (Baxter et al, 2011) and the Clyde Marine Region Assessment (2017) but do not appear on the 2014 list of PMFs. They have been included in the more detailed section of this review.

Elasmobrachs in the Solway include the following;

The basking shark (Cetrohinus maximus) is the second largest fish in the world with an average length in British waters of about 7.5m. They can be seen all around the British Isles, particularly when it is calm and sunny and they are ‘basking’ on the surface. This shark feeds on plankton sieved out of the water through its gill rakers. During the winter basking sharks shed their gill rakers, move to deep water and do not feed. The gill rakers re-grow the next spring. Little is known of their breeding habits, other than their slow reproductive rate. Populations have declined 50-80% in recent years (Baxter et al, 2011). For more general information on basking sharks please visit the Marine Life Information Network page.

The blue shark (Prionace glauca) is a highly migratory species undertaking trans-atlantic migrations. They visit the UK, including the Solway Firth, during summer months. Females are generally larger than males and can grow up to 3.8m in length. They can be seen from the water surface into the depths to maximum depths between 350m and 600m. They can be found in single-sex shoals. Blue sharks are relatively fast growing, maturing within 4-6 years, and have a varied diet including scavenged meat, fish, sharks, and crustaceans. For more general information on blue sharks please visit the Marine Life Information Network page.

Porbeagle sharks (Lamna nasus) is a member of the Lamnidae shark family, as is the great white shark. This species is usually around 2.5m long in UK waters, although they can be longer elsewhere. These sharks are spotted in inshore waters, but generally prefer deeper waters. Porbeagles feed primarily on fish and are endothermic, meaning they can maintain their body temperature higher than the water surrounding them and prefer water between 2 and 18°C. They are of high commercial value and are also a valued game fish, although are mostly released once caught. For more general information on porbeagle sharks please visit the Marine Life Information Network page.

The spiny dogfish/spurdog (Squalas acanthius) is a small dogfish. This species is very common and was traditionally exploited throughout the Celtic Seas. Globally spiny dogfish are one of the most abundant elasmobranchs species. Despite this ‘abundance’ they are still classified as ‘vulnerable’ with a ‘decreasing population’ on the IUCN red list of endangered species. Spiny dogfish are highly migratory and are venomous, with their dorsal fins having venomous spines at the base. Spiny dogfish are distributed throughout Scottish waters with females growing larger than males to a maximum of around 1.6m. They are typically at depths between 10m and 200m. For more general information on spiny dogfish please visit the Marine Life Information Network page.

The common skate (Dipturus batis) is found on the sea floor. Shallower water is favoured by juvenile skates, although they have a vast range between 10-600m. The common skate can grow up to 3m long and can live for between 50-100 years. Their dorsal surface is olive grey/brown with lighter patches and they have a long, pointed snout. Juveniles have large orbital thorns. They are now far from ‘common’ as a result of overfishing. Common skates are considered rare but have been recorded around Scotland and England. For more general information on common skates please visit the Marine Life Information Network page.

Sandy rays (Leucoraja circularis) are typically found around depths of 100m, these rays can reach a maximum length of 120cm. Other than the fact that females lay eggs on the sandy seabed from August to November little is known of the reproductive strategy of sandy rays. For more general information on sandy rays please visit the Marine Life Information Network page.

The tope shark/school shark (Galeorhinus galeus) is a species which can grow to almost 2 metres long. Tope sharks must be returned by anglers and cannot be targeted by fisheries in Scotland and England. They are still targeted elsewhere and illegally, often targeted and exploited for liver oil, in addition to meat and fins. This species is one of the largest inshore species of shark found within the inshore waters of the UK, and is a popular species to recreationally fish for during the Solway during the summer. For more general information on tope sharks please visit the Marine Life Information Network page.

The following list features elasmobranchs species known to be present in the Solway, according to the Ocean Biodiversity Information System, which do not appear on Scotland’s list of Priority Marine Features (PMF). Any species featured on England’s Features of Conservation Interest (FOCI) list are indicated with the acronym FOCI;

Common smooth-hound sharks (Mustelus mustelus). It is advised to release smooth-hound sharks if caught in the Solway recreationally. Highlighted in Solway Firth Partnership’s Recreational Sea Angling webpage.
Small Spotted Catshark (Sayliorhinus canicula)
Nurse-hound shark (Scyliorhinus stellaris)
Angel Shark (Squatina squatina) (FOCI)
Thornback Ray (Raja clavata) (FOCI) are common throughout UK waters, despite being considered as ‘near threatened’ globally, according to the North Western IFCA Thornback rays are commercially fished within the north western district from shore and trawlers. Thornback rays are also common in the Solway. It is advised they are released if caught in the Solway recreationally. Highlighted by Solway Firth Partnership’s Recreational Sea Angling webpage.
Small Eyed Ray (Raja microcellata)
Spotted Ray (Raja montagui)
Undulate Ray (Raja undulata) (FOCI)
Marbled Electric Ray (Torpedo marmorata)

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, ‘Spiny Dogfish (Squalas acanthias) (Catch Per Unit Effort) (Priority Marine Feature)‘ © Crown Copyright, All rights reserved, and ‘Basking shark (Cetorhinus maximus) sightings and distribution (Priority Marine Feature) (SNH WMS)‘ © Crown Copyright, All rights reserved.

Sharks, skates and rays

Conservation Status

As mentioned previously, elasmobranchs often have slow growth rates and low fecundity, meaning that their populations need protected to avoid declines in abundance. Some conservation methods are discussed below, but note that this is not an exhaustive list and conservation comes in many forms. For example another method of conserving elasmobranchs not discussed below is through the Convention on International Trade in Endangered Species of Wild Fauna and Flora. This is a convention which focuses on ensuring the trade of animals does not threaten the survival of that species. Basking sharks are included within this Convention as are other elasmobranchs.

The UK Biodiversity Action Plan has been succeeded by the UK-Post 2010 Biodiversity Framework and is the document for the joined UK-wide work towards achieving the EU Biodiversity strategy and Aichi Targets. Governments of the UK also each have their own biodiversity strategies focussed on more specific country level biodiversity. UK BAP priority species and habitats are those which are considered to be the most in need of conservation and the most threatened on a UK-wide level. The lists are used to help each UK jurisdiction draw up their own specific lists, discussed below. All of the Solway elasmobranchs listed above are featured on England’s List of Species of Principal Importance (SPI), with the exception of the sandy ray. This list is required under s.41 Natural Environment and Rural Communities Act (2006). All of the species are also listed on the statutory Scottish Biodiversity list (SBL) required under Section 2(4) of the Nature Conservation (Scotland) Act 2004. The species on these statutory lists have been identified as threatened and requiring conservation efforts to help maintain biodiversity, through efforts outlined in the respective countries Biodiversity Strategies.

Scotland also has devised a list of ‘Priority Marine Features‘ (PMF) to help guide and deliver conservation efforts in ‘A Strategy for Marine Nature Conservation in Scotland’s Seas‘ and help with consistent conservation advice within Scottish waters. Alternatively, England has a list of Features of Conservation Interest (FOCI), which are rare/threatened species or habitats used to help identify areas for designations as Marine Conservation Zones in England.

The International Union for Conservation of Nature and Natural Resources, Red List of Threatened Species provides a ‘status’ (IUCN Status) indicating how close species are to becoming extinct. Assessments are conducted which provide the information to assess how close species are to extinction, and then a concern level is assigned to the species (from least concern to extinct). The assessments can be on varying scopes, with some global and some smaller in scale.

The OSPAR list of Threatened and Declining Species and Habitats is the resulting list of the assessment of species and habitats which need protection outlined in OSPARs Biological Diversity and Ecosystems Strategy. This list guides the OSPAR Commission in future work and protection through either OSPARs own measures, or through cooperation of other authorities. It is recommended by OSPAR that this list is also considered during the Environmental Impact Assessment (EIA) stages of developing new activities. As the Solway is within the OSPAR marine area this is relevant to the EIAs undertaken.

Scottish Priority Marine Features (PMF) List available here. UK Biodiversity Action Plan (UK BAP) Species descriptions are available here. Species and Habitats of Principal importance (SPI) England. List available here. Features of Conservation Interest (FOCI) (Marine Conservation Zone Features) England. List available here. Scottish Biodiversity List (SBL) Scotland. List available here.
Solway Species	IUCN assessment scope, status, and most recent assessment year*	Conservation Status (Scottish/English waters)	Population trend (IUCN Population Trend)	Presence
Basking shark, Cetorhinus maximus	European; Endangered (2014) Globally; Endangered (2018)	PMF/UK BAP/ FOCI/ SPI/ SBL OSPAR list of Threatened and Declining Species	Declining	Scotland/England
Blue shark, Prionace glauca	European; Near threatened (2014) Globally; Near threatened (2018)	UK BAP/ FOCI/ SPI/ SBL	Declining
Common skate, Dipturus batis	European; Critically endangered (2015) Globally; Critically endangered (2006)	PMF/ UK BAP/ FOCI/ SPI/ SBL OSPAR list of Threatened and Declining Species	Declining
Porbeagle shark, Lamna nasus	European; Critically Endangered (2015) Globally; Vulnerable (2018)	PMF /UK BAP/ FOCI/ SPI/ SBL OSPAR list of Threatened and Declining Species	Declining
Sandy ray, Leucoraja circularis	European and Globally; Endangered (2014)	PMF/ UK BAP/ FOCI/ SBL	Declining
Spiny dogfish (Spurdog), Squalus acanthias	European; Endangered (2014) Globally; Vulnerable (2016)	PMF/ UK BAP/ FOCI/ SPI/ SBL OSPAR list of Threatened and Declining Species	Declining
Tope Shark, Galeorhinus galeus	European; Vulnerable (2014) Globally; Critically Endangered (2020)	UK BAP/ FOCI/ SPI/ SBL	Declining

*Please see the references section for each IUCN assessment individually referenced.

Protection from Over Exploitation;

Many species of sharks, skate and rays are under fishing restrictions to help protect, maintain or grow their population. Globally there are issues with targeting species of elasmobranchs for a variety of reasons. Given the value placed on shark fins in certain markets illegal fishing of sharks, removing their fins and disposing off the carcass at sea are ongoing issues. An Oceana report in 2009 discussed the mislabelling of sharks caught by Spanish vessels, labelling (likely) tope sharks as hake (Merluccius senegalensis). The fins of these sharks were removed and the labelling was in an attempt to cover these sharks being caught without authorisation.

Basking sharks are protected against being intentionally killed, injured or taken as well as protection against disturbance, in accordance with the Wildlife and Countryside Act 1981 (as amended). In Scotland this also includes recklessly killing, injuring or taking basking sharks and harassment of this species. There is also a prohibition on EU vessels landing, targeting, retaining and transporting basking sharks and porbeagle sharks in all waters, and prohibiting third country vessels from these activities in EU waters, as per; Council Regulation (EU) 2019/124.
Common skates and Spiny Dogfish/ Spurdog (referred to as Picked Dogfish) are also prohibited from being caught within the International Council for the Exploration of the Sea (ICES) subarea 7 as are tope shark when caught with longlines (the Solway falls within subarea 7, division 7a).

Blue sharks are placed under a Total Allowable Catch (TAC) restriction under Annex ID of Council Regulation (EU) 2019/124, however are often exploited due to their fin value, or targeted for recreational fishing. As blue sharks are highly migratory controls on TAC will only have limited success as the sharks will migrate outside of the area under controls. Under Annex IA of the regulation sandy rays are placed under a TAC in place for the catching of a variety of skates and rays. There are also minimum catch sizes for ray species in the English Solway as laid out by the North West IFCA, these apply to commercial and recreational fishing, and means that rays smaller than 45cm including wings caught in the English Solway must be returned.

Tope sharks cannot be targeted, caught, retained or transported when they have been caught by longline within certain ICES areas, including subarea 7 (including the Solway) according to Council Regulation (EU) 2019/124.

Tope sharks are considered a restricted species for English vessels according to the Tope (Prohibition of Fishing) Order 2008, they cannot be landed if caught by rod and line or beheaded, and also vessels are restricted to 45kg live-weight catch of tope. In Scottish waters, catching tope is prohibited by Scottish or British fishing vessels, as per The Sharks, Skates and Rays (Prohibition of Fishing, Trans-shipment and Landing) (Scotland) Order 2012, unless caught by rod and line, or hand-line. This Order also places prohibitions on the transportation or tope and landing of tope in Scotland regardless of where it is caught. Each of these prohibitions has details of application within the Order, please see the Order for details. Article 7 of The Sharks, Skates and Rays (Prohibition of Fishing, Trans-shipment and Landing) (Scotland) Order 2012 also prohibits the landing of certain species of shark, skate and ray in Scotland, specifically; ‘The landing of any specified species caught by rod and line or hand-line (wherever caught), from a boat or vessel to which this article applies, is prohibited in Scotland.’ Several of the species which fall under this prohibition are known to occur in the Solway, such as; Common Skate, Porbeagle Shark, and Spiny Dogfish (referred to as Spurdog).

Sharks, skates and rays

Pressures

In the Solway specifically these species are not the focus of fisheries such as scallops and whelks on both the Scottish and English sides, although thornback rays are recorded as the fourth most landed species on the English side of the Solway in 2018, with 63 tonnes being landed. Furthermore, elasmobranchs are under a variety of protections, as discussed above, and restrictions on fishing in the UK, helping to alleviate this pressure in the UK. The International Council for the Exploration of the Sea has a Working Group on Elasmobranch Fishes. This working group conducts stock assessments on a biennial basis for a variety of elasmobranchs species. Various reports from the working group are available here.

Bycatch remains a pressure for elasmobranchs. They can be caught up in nets or fishing gear intended for other species. Species returned to the sea from bycatch may be damaged or hurt causing them to die despite being returned. It is estimated that the majority of the approximately 20 million blue sharks caught globally each year are via bycatch (Marine Conservation Society, n.d). For slow growing elasmobranchs bycatch can negatively impact the abundance of the species.

In addition to their removal by fisheries activities, either on purpose or accidentally, these species also struggle with disturbance, although basking sharks are protected against being intentionally killed, injured or taken, disturbance or harassment be it intentional or reckless in accordance with Schedule 5 of the Wildlife and Countryside Act 1981 (as amended). In Scotland this also includes recklessly (only intentionally in England) killing, injuring or taking basking sharks. Disturbance through development in the marine environment can also impact elasmobranchs. Changes in habitat, increased vessel traffic, and construction, all impact these species negatively during the construction phase of developments and beyond.

Ship strikes can affect basking sharks and other species frequently found close to the sea surface. Collisions with elasmobranchs can cause damage or even death by striking, and some species are at more risk of collision than others due to depth preference. Basking sharks in particular are vulnerable to strikes given their seeming lack of awareness of vessels. They are also most vulnerable during the summer when surface feeding, especially in warm, sunny weather.

Tope sharks can be sensitive to siltation, which can negatively impact reproduction.

Plastics and marine litter are increasingly becoming a widely known pressure on all marine species and in marine food webs. Elasmobranchs are affected by marine plastics and litter through becoming trapped, entangled, or strangled in plastics. They can also consume prey which has already fed on plastics or mistake plastics, such as plastic bags, for consumable prey. Basking sharks, which are filter feeders, may be directly consuming micro plastics passing through their gill rakers. Once consumed, directly or indirectly, plastics can build up in the shark, skate, or ray, filling the stomach, restricting nutrient intake, and potentially releasing toxins.

There are other potentially damaging activities such as the use of electromagnetic frequencies, which have the potential to impact the elasmobranchs within UK waters around offshore developments. The impacts of these are lesser known.

Image; Thornback Ray. © Solway Firth Partnership. Photographer; Colin Tennant

Sharks, skates and rays

References

Dulvy, N., Notarbartolo di Sciara, G., Serena, F., Tinti, F., Ungaro, N., Mancusi, C. & Ellis, J. (2015). Common Skate – Dipturus batis (European Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 14.07.20)

Dulvy, N.K., Notarbartolo di Sciara, G., Serena, F., Tinti, F. & Ungaro, N., Mancusi, C. & Ellis, J. (2006). Common Skate – Dipturus batis (Global Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 08.04.20)

Ellis, J. (2016). Thornback Skate – Raja clavata (Global Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 08.04.20)

Ellis, J., Soldo, A., Dureuil, M. & Fordham, S. (2015). Spiny Dogfish – Squalus acanthias (European Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 14.07.20)

Ellis, J., Farrell, E., Jung, A., McCully, S., Sims, D. & Soldo, A. (2015). Porbeagle Shark – Lamna nasus (European Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 14.07.20)

Fordham, S., Fowler, S.L., Coelho, R.P., Goldman, K. & Francis, M.P. (2016). Spiny Dogfish – Squalus acanthias (Global Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 08.04.20)

International Union for Conservation of Nature and Natural Resources (2019). Red List of Threatened Species. Available here. (Accessed: 13.03.18)

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

Joint Nature Conservation Committee (2007b). 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)

Marine Conservation Society Website (n.d). Spiny Dogfish- Squalus acanthus. Available here. (Accessed: 08.04.20)

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)

McCully, S., Dureuil, M. & Farrell, E. (2015). Tope – Galeorhinus galeus (European Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 14.07.20)

McCully, S., Ellis, J., Walls, R. & Fordham, S. (2015). Sandy Skate (Ray) – Leucoraja circularis (Global and European Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 08.04.20)

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

Natural England (2010). Habitats and Species of Principal Importance List. Available here. (Accessed: 03.12.19)

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)

Oceana (2009). Keeping the Balance, How Environmental Conventions can be used to protect sharks and their habitats. Available here. (Accessed: 08.04.20)

Oceana Website (n.d.). Spiny Dogfish. Available here. (Accessed: 08.04.20)

Ocean Biodiversity Information System (n.d.). Available here. (Accessed: 22.06.20)

OSPAR Commission (n.d.). List of Threatened and/or Declining Species and Habitats. Available here. (Accessed: 12.03.18)

Rigby, C.L., Barreto, R., Carlson, J., Fernando, D., Fordham, S., Francis, M.P., Herman, K., Jabado, R.W., Liu, K.M., Marshall, A., Pacoureau, N., Romanov, E., Sherley, R.B. & Winker, H. (2019). Porbeagle – Lamna nasus (Global Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 08.04.20)

Rigby, C.L., Barreto, R., Carlson, J., Fernando, D., Fordham, S., Francis, M.P., Herman, K., Jabado, R.W., Liu, K.M., Marshall, A., Romanov, E. & Kyne, P.M. (2019). Basking Shark – Cetorhinus maximus (Global Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 08.04.20)

Rigby, C.L., Barreto, R., Carlson, J., Fernando, D., Fordham, S., Francis, M.P., Herman, K., Jabado, R.W., Liu, K.M., Marshall, A., Pacoureau, N., Romanov, E., Sherley, R.B. & Winker, H. (2019). Blue Shark – Prionace glauca (Global Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 14.07.20)

Scottish Government (2013). Scottish Biodiversity List. Available here. (Accessed: 09.01.20)

Serena, F., Mancusi, C., Clò, S., Ellis, J. & Valenti, S.V. (2009). Common Smoothhound – Mustelus mustelus (Global Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 08.04.20)

Sims, D., Fowler, S.L., Clò, S., Jung, A., Soldo, A. & Bariche, M. (2015). Basking Shark – Cetorhinus maximus (European Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 15.07.20)

Sims, D., Fowler, S.L., Ferretti, F. & Stevens, J.D. (2015). Blue Shark – Prionace glauca (European Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 08.04.20)

Solway Firth Partnership (n.d.) Recreational sea angling. Available here. (Accessed: 08.04.20)

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

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

Walker, T.I., Rigby, C.L., Pacoureau, N., Ellis, J., Kulka, D.W., Chiaramonte, G.E. & Herman, K. (2020). Tope – Galeorhinus galeus (Global Assessment). The IUCN Red List of Threatened Species. Available here. (Accessed: 08.06.20)

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)

Marine Conservations Society (n.d.). Blue Shark – Prionace glauca. Available here. (Accessed: 24.06.20)