An inhabitant of shallow coastal waters, it is found in the northwestern Pacific Ocean off Korea, Japan, and China.

It is characterized by a covering of prickles above and below its snout, but not elsewhere on its body, and a dark ring in the middle of each "wing" (though this may be indistinct in adults).

The mottled skate was scientifically described by ichthyologist Liu Fah-Hsuen in a 1932 issue of The Science Reports of National Tsing Hua University.

[6] Reaching a maximum known length of 1.12 m (3.7 ft),[1] the mottled skate has a diamond-shaped pectoral fin disc with a broad, elongated snout that tapers to a point.

Prickles cover the dorsal and ventral sides of the snout, but they do not extend onto the back or belly as in the similar big skate (R. binoculata).

Breeding occurring almost year-round, peaking from April to June and from November to December, and pausing only in midsummer.

The eggs are generally deposited on sandy or muddy flats; off Hokkaidō, they are commonly laid inside culturing cages used by scallop farms.

In South Korea, it is the predominant species of skate (known as hong-eo) consumed, and is one of the most expensive fish on the market at $10–30/kg; it is popularly served at wedding feasts.

Japanese fishermen have also reported declines in recent years, while off China, the numbers of all fish species are diminishing due to overexploitation and habitat degradation.

The overall decline in the mottled skate population has been estimated at over 30% since the 1980s, and may in fact be severe enough to warrant a status of endangered.