rough skate of the outer continental shelf

Size
Length: 100–150 cm, Weight: 5–15 kg
Lifespan
15–25 years
Diet
Feeds on small fish, crustaceans and worms. Uses electroreceptors to detect buried prey. Crushes shells with flat, pavement-like teeth designed for grinding. Emerges at night to hunt over sandy and muddy bottoms.
Habitat
Sandy and muddy bottoms in coastal waters. Depth ranges from 10 to 300 metres. Often buried in sediment during day with only eyes showing. Emerges at night to hunt. Prefers soft substrates for camouflage.
Range
Coastal waters of North and South Islands. Extends from Northland to Stewart Island. Most common on sandy bottoms of continental shelf. Also found in southern Australia. Prefers shallow to moderate depths.
Endemism
Endemic
Main Threats
Bycatch in bottom trawl and set net fisheries is primary threat. Habitat disturbance from dredging and bottom trawling affects survival. Slow reproduction makes populations vulnerable to overfishing pressure. Localised declines noted.
Population
Populations considered stable but localised declines occur in heavily trawled areas. Caught as bycatch in hoki, snapper and flatfish fisheries. Quota management limits total bycatch. Better species-specific data needed for accurate stock assessments.
Conservation Status
Not Threatened
Run a hand along the back of a rough skate. The difference is felt immediately. Small thorn-like denticles cover the upper surface. They give the fish its name and its texture. This is not a smooth, slippery fish. It feels like fine sandpaper. A rough customer of the seafloor. The Māori name Uku captures this quality. It compares the texture to certain types of stone and rock found along the coast. A fish that feels like rock. The rough skate glides over sandy and muddy bottoms. Wing-like pectoral fins make it look like a kite flying underwater. It buries itself in sediment during the day. Only its eyes show. It waits. At night it emerges to hunt. Electroreceptors detect buried prey. Small fish, crustaceans and worms. It crushes shells with flat pavement-like teeth. These are designed for grinding rather than tearing. A fish that waits, then crushes. Like all skates, the rough skate lays eggs. Leathery cases called mermaid's purses are deposited on the seafloor. Each contains a developing embryo. These egg cases often wash up on beaches after the young skate has hatched. They puzzle beachcombers who find strange black rectangular objects with horns at each corner. A mermaid's purse. A skate's cradle. Populations are considered stable. Localised declines have occurred in heavily trawled areas. The rough skate is caught as bycatch in fisheries targeting hoki, snapper and flatfish. Slow reproduction makes it vulnerable. The seafloor is sandy. The skate buries itself. Eyes just visible. Waiting. The trawl net drags. The skate is caught. It does not know it is bycatch. It does not know it is vulnerable. It just wanted to crush a shell.