Sharks, Skates and Rays (Elasmobranchs) in Scotland 

The Scottish Government (2011) lists 36 species of elasmobranchs known to be found in Scottish waters, including 24 shark species, 7 ray species and 5 skate species (Scottish Government, 2011) – see list. The Scottish Seabird Centre (n.d.) suggests this number could be as high as 66. 

Elasmobranchs are part of the Chondrichthyes group, in addition to Chimaeras. Chondrichthyes are distinguished by their cartilaginous skeleton, as opposed to the more common boney skeleton (Shark Trust, 2020). Another distinguishing feature of the group is their reproductive cycle, generally taking a long time to produce small numbers of mature young. The 3 main reproductive styles are listed below (from Shark Trust, 2020):
- Viviparous: The young grow within the mother, provided with nutrients and oxygen through an umbilical cord – the most similar form to reproduction in mammals. 
- Ovoviviparous: The young grow in an egg membrane within the mother. They hatch insider her and are born live. 
- Oviparous: The female lays egg cases on the seabed or seaweed, which will develop and hatch on their own. These eggs are thick and leathery, which may wash up onto beaches – they are known as ‘mermaid cases’. 

Sharks commonly have torpedo shaped bodies, while skates and rays have flat bodies. The difference between skates and rays comes down to their reproductive system, wherein skates are born from egg cases while rays are born live. Additionally, skates tend to have broader, thicker tails than the thin tails of rays. (Shark Trust, 2020). It should also be noted that sometimes their names are not accurate to their species, such as the ‘spotted ray’ being, scientifically speaking, a skate (Shark Trust, 2020). 

Sharks play a highly important role in marine biodiversity, often occupying the role of apex predator, keeping other specie’s populations healthy and controlled (Shark Trust, 2020). However, centuries of overhunting have severely damaged the population numbers of all Elasmobranchs. A 2021 study found a 71% decline in shark and ray species abundance since 1970 (Pacoureau et al¸2021), while another found that 1/3 of all chondrichthyan species now fall into the ‘threatened’ classification (Dulvy et al, 2021).