Featured Elasmobranch – Golden Skate

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Featured Elasmobranch – Golden Skate

Photo Copyright: Museum of Comparative Zoology, Harvard University

 

Golden Skate

Bathyraja smirnovi (Soldatov & Pavlenko, 1915)

Family Arhynchobatidae

Identification: Distinguished from other members of the subgenus Arctoraja by absence of complete row of middorsal thorns; disc more than 1.1 times as wdie as long; anterior pelvic fin lobes moderately long, and tail length less thant distance from snout tip to cloaca posterior margin.  It can be further distinguished from similar regional species B. parmifera by the underdeveloped ridges of its claspers in adult males. This species has a larger mouth than other regional Bathyraja spp. Dorsal surface is golden-brown in color, lighter ventrally.

Size: Maximum total length (TL) is at least 102cm, but reach 116cm. Maturity is at about 100 cm TL for males and 92cm TL for females.  Size at birth is roughly 22cm TL.

Distribution: Found in the Northwest Pacific from the northern part of the Sea of Japan to the Sea of Okhotsk (North of Japan) and to the western Bearing Sea. Until recently this species was thought to possibly either be a synonymy of B. parmifera or to possibly occur in the eastern Bering Sea.

Habitat: Occurs at depths from 100-1,125m and is found on sandy or muddy substrate.  There is little other information available on its habitat preference.

Biology: Oviparous with egg cases that are oblong with stiff pointed horns and range from 12.4-15.0cm long and 8.7-9.0cm wide. The egg capsules are deposited on muddy or sandy flats.  Mating behaviors include pairing with an embrace. More recently, dense patches of eggs have been found that “appeared to have been revisited by adults of the species through time”. This discovery occurred near the Shiribeshi Seamount in the northern Sea of Japan by the Department of Biology, East Stroudsburg University and the Marine Biodiversity Research Program at the Japan Agency for Marine–Earth Science and Technology.They have been reported to feed on amphipods, decapods, fishes, euphausids, and squid.

General Interest: B. smirnovi is known to be a common bycatch species in the Sea of Japan but is often kept and sold. However, it has been reported that the majority of its population occurs outside the range of most fisheries giving it a “Least Concern” assessment on IUCN Red List of Threatened Species. This and other similar species of the genus Arctoraja were frequently misidentified and it was unclear whether this species was even valid. However, recent molecular and morphological studies have reveal that this species is valid and that it can be distinguished from other similar species, e.g. B. panthera, B. parmifera, and B. simoterus.

 

Matt Lawson

CSU Monterey Bay