Featured Elasmobranch – Pacific White Skate

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Featured Elasmobranch – Pacific White Skate

B_spinossisima-MBARI pic

July 2009

 

 

 

Pacific White Skate

 

Bathyraja spinosissima (Beebe & Tee-Van, 1941)

 

Family Arhynchobatidae (softnose skates)

Identification: A softnose skate with a disc that is slightly wider than long, broadly rounded pectoral fin apices, a disc surface evenly covered with numerous, small prickles above and below, giving it a shagreenlike texture to the touch. There are no enlarged thorns on the dorsal surface except for alar spines in adult males, but a single median row of tail thorns. The two dorsal fins are similar in size and lack an interdorsal thorn. The tail is slightly longer than the disc width. Coloration is a uniform pale salty gray above and below, with a dusky outer disc margin.

Size: A large species where females may reach up to 2 m in total length and males reach at least 1.5 m TL.

Distribution: This species ranges from Central America, and possibly the Galapagos Islands, to Waldport, Oregon, and possibly to the Sea of Okhotsk off northern Japan, although this may be a different species.

Habitat: Considered an extremely rare skate, known from only a few records, recent video analysis of 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 boulder and rocky reef substrate type. This is one of the deepest known skate species with a depth range of 800 to over 3,000 m.

Biology: The reproductive mode, as with all skates, is oviparous. The egg cases are large with longitudinal striations and an olive green color. Size at birth is large, about 25 cm TL. What little is known about their diet indicates that they consume benthic fishes.

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. NOTE: Given the rarity of this species if one should be captured it should be deposited into the fish collection at a major museum such as the California Academy of Sciences (Fish Collection Department) in San Francisco or you can contact us at the PSRC at the below address.

By David A. Ebert

Pacific Shark Research Center

Moss Landing Marine Laboratories

8272 Moss Landing Road

Moss Landing, CA 95039

debert@mlml.calstate.edu