Thornback ray

How it lives

Found on mud, sand and gravel from the shallows to about 1,020 m (3,350 ft), and most commonly at 10 to 60 m (33 to 197 ft) (FishBase). It buries itself in sediment by day and hunts at dusk (Wildlife Trusts). It lays eggs, usually about 60 to 140 egg cases a year and up to 170, with each capsule 5 to 9 cm long. Mating runs from February to September and peaks in June. Eggs hatch after about 4 to 5 months, and the pups are about 11 to 13 cm long. Maturity comes at about 6 to 8 years, and ages of at least 15 to 17 years have been recorded (FishBase, OSPAR).

Where it goes

It does not travel far. Of the thornbacks recaptured off Ireland, 79 percent were within 10 km of where they were tagged. In the Azores, 92 percent were recaptured within 40 km. Young rays stay inshore, and adults move seasonally to breed in spring and summer (Fisheries Ireland).

We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.

Populations

Worldwide: Near Threatened on the IUCN Red List (assessed in 2023, FishBase). OSPAR has listed it as threatened or declining since 2008, but its latest assessment finds biomass increasing in OSPAR regions II and III. It is stable to increasing in region IV and stable at a low level in region V. Recovery from depletion is slow. In Irish waters the population appears to be growing, and a study in the Azores called the stock relatively healthy (catch fell from 171 t in 2015 to 70 t in 2017). In the Solway Firth it has been heavily fished (Wikipedia).