Sailfin sandfish

Arctoscopus japonicus

FAMILY

Trichodontidae

TAXONOMY

Arctoscopus japonicus Steindachner, 1881, Strietok, Sea of Japan, and, questionably, Sitka, Alaska. Originally described as Trichodon japonicus by Steindachner, but placed in its own genus by Jordan and Evermann (1896) to emphasize the differences from the only other species in the family, T. trichodon.

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

Compressed, wedge-shaped fishes, with an upturned mouth, fringed lips, spines on the preopercle, and a scaleless body. Two widely spaced dorsal fins, the first having eight to 14 spines and the second having 12–15 segmented rays. Spineless anal fin, with 29–32 segmented rays, and large pectoral fins. Brown mottling dorsally, pale or silvery ventrally, dark bands on both dorsal fins. Grows to 7 in (17 cm).

DISTRIBUTION

Korea to the Sea of Japan, Sea of Okhotsk, and the Bering Sea to Alaska.

HABITAT

Sandy-mud bottom at 650–1,300 ft (200–400 m), sitting on or in the substrate.

BEHAVIOR

Nothing is known.

FEEDING ECOLOGY AND DIET

Not known; perhaps a sit-and-wait predator or, similarly to trachinids, hides in substrate during the day and is active at night. Feeds primarily on mysids, crangonids, and small fishes.

REPRODUCTIVE BIOLOGY

During November and December there is a conspicuous spawning migration from deeper water to areas of seaweed at 6–33 ft (2–10 m). Eggs, which are about 0.14 in (3.5 mm), are stuck onto Sargassum species in spherical masses of about 600–2,300; they hatch asynchronously in about two months. Juveniles school and spend about three months in shallow water before moving into deeper water.

CONSERVATION STATUS

Fisheries in parts of northern Japan collapsed in the early 1980s. Record catches in the late 1960s reached 20,000 tons and held at about 15,000 tons until the late 1970s. By 1984 the catch had plummeted to just 74 tons. A moratorium on fishing was enforced from September 1992 to September 1995, and fishing began again during the spawning season of 1995, but catches remained below 1000 tons up to 1999.

SIGNIFICANCE TO HUMANS

An important food fish in northern Japan, caught by trawl net, set net, and dragnet as the fish come inshore to breed. They are eaten fresh or stored pickled in a mixture of salt and yeast for later consumption. The eggs, called buriko, also are eaten, particularly at the New Year. When catches were plentiful, excess fish were dried and used as fertilizer.