Thorny Skate

Amblyraja radiata

SARA Status
No Status
NS
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

SARA Status

  • No Status NS
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX
COSEWIC Status
Not at Risk
NR
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

COSEWIC Status

  • Not at Risk NR
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX

Description

Thorny Skate (Amblyraja radiata) belongs to the Class Chondrichthyes, which includes all shark and skate species. Thorny Skate is a relatively large skate; it can reach up to 90 cm total length (7.5 kg) on the Labrador Shelf, 110 cm (12.5 kg) on the Grand Banks, and 100 cm (10 kg) in the Gulf of St. Lawrence, Scotian Shelf, and Gulf of Maine. It varies among regions in overall size, body proportions, number of thorns (except on its midline), growth, and age at maturity. It is distinguished from other skates in the Northwest Atlantic Ocean primarily by a row of 11–19 large thorns on the midline of its back and tail. The upper body colour can be highly variable among individual Thorny Skate, ranging from yellow-edged dark spots on light brown to an almost uniform dark brown. The underside of its body is uniformly white, rarely with a few small, non-symmetrical, darkly pigmented markings. Its average age at maturity is 11 years, and it lives at least 20–30 years.

Habitat

Thorny Skate live on the ocean bottom over a wide range of depths (18–1200 m) and usually in water temperatures of 0–10 °C. They can be found on a variety of bottom types, such as sand, gravel, mud, and broken shells.

Thorny Skate is the most widely distributed and abundant skate species in the North Atlantic Ocean. In Canadian waters, it is among the most widespread and abundant bottom-dwelling fish species and is continuously distributed from Baffin Bay, Davis Strait, Labrador Shelf, Grand Banks, Gulf of St. Lawrence, Scotian Shelf, and Bay of Fundy to Georges Bank. The highest concentrations of this fish in these waters are found along the southern Grand Banks off Newfoundland and on the eastern portion of the Scotian Shelf.

Thorny Skate distribution

Approximate boundary of Thorny Skate distribution in Canada, as adapted from COSEWIC 2012.

Map depicting the Canadian distribution of Thorny Skate. In Canadian waters, it is continuously distributed from Baffin Bay, Davis Strait, Labrador Shelf, Grand Banks, Gulf of St. Lawrence, Scotian Shelf, and Bay of Fundy to Georges Bank. This map was adapted from the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) 2012 assessment and status report on the Thorny Skate (Amblyraja radiata) in Canada.

Threats

COSEWIC states that threats include both directed fishing and bycatch, as well as predation in the south (e.g., southern Gulf of St. Lawrence). Although fishing effort and catches have generally decreased, Thorny Skate continue to be caught in a directed fishery (around Newfoundland and Labrador and outside Canada's Exclusive Economic Zone (EEZ) in the Northwest Atlantic Fisheries Organization (NAFO) Regulatory Area) and as bycatch in other groundfish fisheries (both inside and outside Canadian waters).

Further Information

For more information, visit the Species at Risk registry

Thorny Skate

Thorny Skate

Illustration of a Thorny Skate viewed from the side. It is a flattened fish with a disc-shaped body covered in thorns and a slender tail. This species is distinguished from other skates in Canadian waters primarily by a row of 11–19 large thorns on the midline of its back and tail. The upper body colour can be highly variable among individual Thorny Skate (ranging from yellow-edged dark spots on light brown to an almost uniform dark brown). The underside of its body is uniformly white, rarely with a few small, non-symmetrical, darkly pigmented markings.

Scientific name: Amblyraja radiata
SARA Status: No Status
COSEWIC Status: Special Concern
Region: Nunavut, Quebec, New Brunswick, Prince Edward Island, Nova Scotia, and Newfoundland and Labrador

Did You Know?

Thorny Skate reproduce by laying an embryo in a hard-shelled egg case (“Mermaid's purse”) on the bottom of the ocean, and each female produces between 6 and 40 egg cases per year. Hatching success rate is estimated at 38%, meaning approximately 15 hatchlings survive per female each year. Little is known about predators of Thorny Skate, but the embryo developing inside of an egg case has sometimes been found eaten by a shell-drilling gastropod, while juveniles and adults may be eaten by marine mammals, other skates, and larger fish. Thorny Skate have a highly varied diet of bottom-dwelling fish and invertebrates, which changes with prey availability and skate body size; small skates eat more squid, marine worms, and amphipods (“sea lice”), while larger skates eat Sand Lance, Capelin, smaller Haddock, and Snow Crab.

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