Featured Elasmobranch-Butterfly Skate

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Featured Elasmobranch-Butterfly Skate

October 2011

Butterfly Skate

Bathyraja mariposa (Stevenson, Orr, Hoff & McEachran, 2004)

Family Rajidae (Skates)

Identification: A medium sized skate with a broad disc, long snout and moderately long tail. The dorsal disc surface is covered uniformly with dense fine denticles except near the disc margins. This is one of only four Alaskan skate species that lacks thorns on the disc surface. The dorsal surface color is a rather striking greenish brown with bright yellow blotches and a predominantly snowy white ventral surface.

Size: A maximum size of 76 cm total length for females and at least 70 cm for males.

Distribution: This skate may endemic as it has only been collected from bottom trawl surveys off the Aleutian Islands and in the Bering Sea from Seguam Pass, Tanaga Pass, Petrel Bank and Islands of Four Mountains at depths ranging from 90-448m.

Habitat: This is a poorly known skate species inhabiting depths of 90-448 m.

Biology: Females are mature at 76 cm TL and males at 70.2 cm TL.  Reproduction is oviparous as egg cases have been recorded and described for this species. Nothing is known on the diet of this skate.

General interest: The IUCN lists this species as Data Deficient due to a lack of life history information and data on population trends. This species was relatively recently described from only a few dozen specimens. It is probably taken as bycatch of the bottom trawl and bottom seine fisheries in the Bering Sea, however, no specific catch data are available. The species is named the butterfly skate due to the coloration pattern on the pectoral fins.

By: Emily Donham

Ichthyology Lab

Moss Landing Marine Laboratories

edonham@mlml.calstate.edu