A giant of the seabed, the flapper skate (Dipturus intermedius) is a huge, table-sized fish of increasing scarcity. Once common across the north and eastern Atlantic, overfishing has driven the species to the brink, and it is now on the International Union for Conservation of Nature (IUCN) Red List, meaning it faces ‘an extremely high risk of extinction in the wild’.
Part of the issue is the flapper’s slow growth rate. A male skate reaches sexual maturity between seven and 14 years, while the female takes anywhere between nine and 26 years. She will produce a maximum of 40 eggs over a two-year cycle; such slow reproductivity means the species’ recovery will take considerable time. Natural predation of younger fish by sharks, seals or adult skate will present a greater impact on overall survival, with too few fish reaching maturity.
What does a flapper skate look like?
The adult fish are impressively vast. The pectoral fins are huge, forming triangular ‘wings’ that give the fish its rhombic form. The eyes are small in relation to the body size and positioned on top of the head either side of the shallow, spinal ridge that runs from the point of the snout, along the back and down the tail. The tail itself is slim and tapered, with two dorsal fins positioned towards the end and a row of small, inter-dorsal thorns on either side.
The flapper skate is oviparous, meaning the eggs are fertilised while inside the female’s body before being deposited on sand or among rubble on the seabed. The female is able to store sperm, so eggs may be subsequently fertilised from the same mating event. The egg-cases are typical of cartilaginous fish such as rays and sharks, resembling leather pouches with horns on each corner, known collectively as mermaid’s purses.
How big is a flapper skate?
They measure up to 23cm long and 14cm wide, and incubation varies according to water temperature but may take as long as 18 months. When hatched, the young skate measure around 25cm long and are immediately independent, feeding on invertebrates, crustaceans and small fish. They are slow growing, but their longevity (flapper skate may live as long as 100 years) enables them to attain great size. The larger females may measure close to three metres in overall length.
The flapper skate and blue skate (Dipturus batis) were formerly recognised as a singular species – the common skate. They look similar, although the blue (which is actually brown) tends to be found further south. The flapper is olive-green, with pale splotches forming patterns across the body. Beneath the body, the fish is pale-grey, while the mouth is underslung and central with powerful jaws and multiple rows of small, pointed teeth.
Ongoing research
Teams from the Royal Zoological Society of Scotland and NatureScot are running a flapper skate health screening programme in Scottish waters to help ensure the future of the species.
