Thornback Skate

Fascinating facts about the Thornback Skate

• Thornback rays hug the seafloor from shallow tide-pools to the edge of the continental shelf, preferring mud, sand or gravel. They are most common between 10 and 60 m deep, yet divers have recorded them as deep as 300 m and occasional individuals down to 1,020 m. This broad depth tolerance lets them exploit both nutrient-rich coastal zones and the cooler, less-fished offshore waters, buffering populations against localized habitat loss while still exposing them to trawl gear that operates across this range.
• A single female can lay up to 170 egg cases a year, though the average clutch is 48-74 eggs. Each oblong capsule measures 5.0-9.0 cm long and 3.4-6.8 cm wide, with stiff, pointed horns that anchor it to the seabed. After a 4-5 month incubation, the pups emerge at 11-13 cm, ready to join the benthic community.
• The IUCN lists the thornback ray as Near Threatened, a status driven by over-exploitation and its slow life history. Declines in landings are linked to intensive trawl fisheries, and some studies suggest the species may already be extinct in parts of the North Sea. Management actions like a 47 % cut in total allowable catch for skates (1999-2005) and minimum landing sizes aim to curb the decline, but localized measures alone are unlikely to reverse regional population losses.
• Adult thornback rays can stretch up to a metre long, but most stay under 85 cm; the heaviest recorded individual tipped the scales at 18 kg. Males top out around 105 cm, while females can reach 139 cm.
• Thornback rays don't reach sexual maturity until they are 7-8 years old and can live up to 15 years in the wild. Females typically mature a bit later than males, about 8.8 years versus 7.1 years.

Sources

Every fact above was checked against these pages, and kept only where one of them states it.

• Wikipedia
• Animal Diversity Web

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