Featured Elasmobranch – Deepsea Skate

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Featured Elasmobranch – Deepsea Skate

B. abyssicola

August 2009

 

Bathyraja abyssicola (Gilbert, 1896)

 

Family Arhynchobatidae (softnose skates)

Identification: A softnose skate with a moderately triangular anterior disc margin, a broadly rounded posterior disc margin, and a disc width slightly greater than its length. Disc dorsal surface with 1-5 nuchal thorns separate from a row of 21 to 31 continuous median tail thorns and an interdorsal thorn. The two dorsal fins are similar in size and close set. Coloration is a uniform purplish gray above, occasionally with small dark blotches, ventral surface similar in color except for whitish areas around the mouth and anterior pelvic fins.

Size: A large species where females may reach up to 1.6 m in total length and males reach at least 1.35 m TL.

Distribution: This species ranges from northern Baja California, from off Coronado Island and Cortes Bank, north to the Bering Sea and as far west as Japan.

Habitat: Considered an uncommon skate video analysis from remote operated vehicles by researchers from the PSRC and the Monterey Bay Aquarium Research Institute have found this skate to actually be quite abundant at depth. Its preferred habitat appears to be on deepsea cobble and rocky reef substrate types. This is one of the deepest known skate species with a depth range of 350 to over 3,000 m.

Biology: The reproductive mode, as with all skates, is oviparous. Females mature at about 1.4 m TL and males between 1.1-1.2 m TL. The egg cases are large with longitudinal striations and an olive green color. Size at birth is large, about 20 cm TL. The deepsea skate is a voracious predator on benthic invertebrates including annelids, cephalopods, and crustaceans, and on benthic teleosts. Larger individual tend to feed on bony fishes in a higher proportion than smaller individuals that prefer invertebrates.

General interest: Occasionally taken as by-catch the preferred depth range and rugged habitat of this species precludes it from being taken in any substantive numbers as by-catch.

By David A. Ebert

Pacific Shark Research Center

Moss Landing Marine Laboratories

8272 Moss Landing Road

Moss Landing, CA 95039

debert@mlml.calstate.edu