Big skate

What it is

The big skate is a large ray with a flattened, diamond-shaped body. Its pectoral fin disk is slightly wider than it is long, featuring a pointed snout that is semi-transparent near the tip. The skin of juveniles is smooth, but adults develop small prickles on their back and underside. Two prominent dark eyespots with pale borders sit on each wing, giving the species its name. The dorsal surface is mottled brown, olive, or grey with white spot rosettes, while the ventral side is white. It lacks an anal fin and has two small dorsal fins on its tail.

Where it lives

This species lives in the north-eastern Pacific Ocean. Its range extends from the eastern Bering Sea and Aleutian Islands south to Cedros Island in central Baja California. It is rare south of Point Conception in California. Big skates inhabit coastal bays, estuaries, and the continental shelf. They prefer sandy or muddy bottoms but may rest on kelp strands. While recorded at depths of 800 metres, they are typically found no deeper than 120 metres. In northern areas, they frequent shallower waters, particularly off British Columbia where temperatures range from 7.6 to 9.4 degrees Celsius.

How it lives

Big skates often bury themselves in sediment, leaving only their eyes exposed. They feed on benthic invertebrates such as polychaete worms, molluscs, and crustaceans, as well as small bottom-dwelling fishes. Younger individuals consume more worms and molluscs. The broadnose sevengill shark is a known predator. The eyespots on the wings likely act as decoys to confuse attackers. Juvenile northern elephant seals sometimes eat their egg cases. Parasites include the copepod Lepeophtheirus cuneifer. Growth rates vary by region, with those in the Gulf of Alaska differing from populations off British Columbia.

Breeding and life cycle

Females lay eggs year-round, with no distinct breeding season. They deposit oblong egg cases, known as mermaid's purses, in pairs on sandy or muddy flats. These cases are the largest of any skate, measuring up to 31 cm long. Each capsule can hold one to seven embryos, though three or four is common. This multi-embryo trait is unusual among skates. Young emerge after nine months, measuring 18 to 23 cm. Males mature at seven to eight years old, while females mature later, at twelve to thirteen years. Distinct spawning beds have been identified where egg cases accumulate.

Fish and people

This skate is one of the most commercially important species off California. It is often caught as bycatch in bottom trawls. The pectoral fins are sold as skate wings, which are baked or fried and sometimes labelled as imitation scallops. Market value increased significantly in the 1990s, leading to a ten-fold rise in catches. A targeted fishery began in the Gulf of Alaska in 2003. Recreational anglers frequently catch and release them. They adapt well to captivity and are common in public aquaria. Fisheries are managed separately in Alaska, British Columbia, and the US west coast.

Status and threats

The World Conservation Union assesses the big skate as least concern. Stock assessments in Alaska, British Columbia, and the contiguous United States have not found evidence of overfishing. However, estimates of sustainable catch and total stock size remain uncertain. The species faces pressure from commercial trawling, but current management appears to maintain stable populations across its range.

Relatives and look-alikes

It is the third largest skate globally, after the flapper skate and the blue skate. In older literature, it was classified under the genus Dipturus or Raja. In 2012, it was moved to the genus Beringraja along with the mottled skate. It is sometimes confused with other large skates in the Pacific, such as the longnose skate, which is also targeted by fisheries in the Gulf of Alaska.

Questions people ask about Big skate

Good reading and sources

• Big skate on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data