Bathyraja microtrachys 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Chondrichthyes Rajiformes Arhynchobatidae

Scientific Name: Bathyraja microtrachys (Osburn & Nichols, 1916)
Common Name(s):
English Fine-spined Skate
Taxonomic Notes: This skate been misidentified as the Roughtail Skate, Bathyraja trachura, but B. microtrachys is clearly a distinct species. Although adult males have not been observed for this species, egg cases have been collected and are distinct from those of other eastern North Pacific skates (D.A. Ebert unpubl. data).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2015
Date Assessed: 2015-01-16
Assessor(s): Carlisle, A.B., Launer, A.L. & Ebert, D.A.
Reviewer(s): Barry, S.N. & Lawson, J.
Facilitator/Compiler(s): Walls, R.H.L. & Dulvy, N.K.
The Fine-spined Skate (Bathyraja microtrachys) is a deepwater skate with a patchy distribution along the west coast of the United States, from Washington State to southwest of San Diego, California. This species occurs at depths of 1,995–2,900 m and is common below 2,000 m, beyond the range of most deepwater fisheries. The only known specimens have been collected by scientific research cruises, there is no reason to suspect that the population has declined, and there are no known threats to this species, resulting in an assessment of Least Concern.
Previously published Red List assessments:

Geographic Range [top]

Range Description:The Fine-spined Skate has a sporadic distribution along the west coast of the United States from Washington State to about 300 miles southwest of San Diego, California (Ebert 2003).
Countries occurrence:
United States (California, Oregon, Washington)
FAO Marine Fishing Areas:
Pacific – eastern central; Pacific – northeast
Additional data:
Lower depth limit (metres):2900
Upper depth limit (metres):1995
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species appears to be fairly common below 2,000 m depth (Ebert 2003). The only known specimens have come from scientific research cruises.
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:

Very little is known about this deepwater skate, which is found in waters between 1,995 and 2,900 m deep (Ebert 2003). It is one of the deepest occurring skate species, having been documented deeper than 3,100 m (Ebert and Davis 2007), and there is evidence of physiological factors restricting their distribution to deep waters (Laxson et al. 2011). Historically, this species was confused other deepwater skates, the Roughtail Skate (Bathyraja trachura) and the Deepsea Skate (B. abyssicola; Ebert 2003). Females mature at 60–70 cm total length (TL) and the largest recorded male was an immature specimen measuring 35 cm TL (Ebert 2003). The size at birth is about 17 cm TL (Ebert 2003). Fine-spined Skates are oviparous, laying egg cases which are small in size, around 81 cm TL (Ebert and Davis 2007).


Use and Trade [top]

Use and Trade: This species is not known to be utilized.

Threats [top]

Major Threat(s):

This species is generally distributed in very deep waters, beyond the range of most fisheries, however they may be taken as bycatch in some deepwater fisheries (Ebert 2003). 

Conservation Actions [top]

Conservation Actions: There are no conservation measures in place for this species.

Classifications [top]

In-Place Research, Monitoring and Planning
In-Place Land/Water Protection and Management
In-Place Species Management
In-Place Education

Bibliography [top]

Ebert, D.A. 2003. Sharks, Rays and Chimaeras of California. University of California Press, Berkley.

Ebert, D.A. and Davis, C.D. 2007. Description of skate egg cases (Chondrichthyes: Rajiformes: Rajoidei) from the eastern North Pacific. Zootaxa 1393: 1-18.

IUCN. 2015. The IUCN Red List of Threatened Species. Version 2015-4. Available at: (Accessed: 19 November 2015).

Laxon, C.J., Condon, N.E. and Yancey, P.H. 2011. Decreasing Urea∶Trimethylamine N-Oxide Ratios with Depth in Chondrichthyes: A Physiological Depth Limit? Physiological and Biochemical Zoology 84(5): 494-505.

Citation: Carlisle, A.B., Launer, A.L. & Ebert, D.A. 2015. Bathyraja microtrachys. The IUCN Red List of Threatened Species 2015: e.T161683A80675182. . Downloaded on 21 August 2018.
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