Featured Species Friday: Deepsea Skate (Bathyraja abyssicola)

This week’s Featured Species is going to the flat sharks! The Deepsea Skate (Bathyraja abyssicola) is a wide ranging member of the Arhynchobatidae family. These skates have been found through the Northern Pacific Ocean from Japan to the Bering Sea, and south to Baja California, Mexico and recently observed for the first time in the Galapagos Marine Reserve (Cerutti-Pereyra, et al., 2018).  The deepsea skate is aptly named for the environment it inhabits. Their scientific name “abyssicola” comes from the Greek “abyssos” which means “bottomless” and “cola” which means “living at depths” (Ebert, 2003). These skates have been found between 1300 – 9528 feet (396 – 2904 m) along continental shelves and slopes (Cook & Zorzi, 2015).

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NOAA (Photographer). (2011 July 17). A deep-sea skate glide through the outskirts of a vent field [Digital Image]. Retrieved from https://commons.wikimedia.org/

There are currently 245 of known species of skates (Ebert & Compagno, 2007). They belong to the order Rajiformes and describe approximately 25% of Chondrichthyans (Cerutti-Pereyra, et al., 2018). Skates, like rays, are flatten cartilaginous fish closely related to sharks. Both skates and rays use their specialized pectoral fins to seamlessly glide through the water. (Klimley, 2013).  The video below, taken at a depth of 2400 m in 2016, shows how with a series of wave like motions the deepsea skate propels itself gracefully through the water.

Serpentproject (Videographer). (2016 February 26). Deep-sea Skate (Bathyraja sp.) [Video Clip]. Retrieved from https://www.youtube.com/

 

Stingrays, like many species of sharks, give live birth. Skates produce egg cases that are sometimes referred to as mermaid’s purses. These hard, rectangular egg cases often have several tendrils that extend out to help anchor them to rocks, corals, and kelp beds during incubation. The egg case of the deepsea skate is rough to the touch with large, robust horns anteriorly and smaller horns at the posterior (Ebert & Davis, 2007).

 

Egg-case-of-Bathyraja-abyssicola-Scale-bar-20-mm
Figure 2. Egg case of Bathyraja abyssicola. Scale bar 20 mm. (Ebert & Davis, 2007).

 

Because the deepsea skate lives at depths that are difficult to access and study, not much is known about their biology or behavior. They are not specifically targeted by commercial fisheries, however, they are sometimes taken as bycatch in deep water trawlers seeking flatfishes in the Bering Sea. In previous years, deep water fishes were considered safe from the fisheries industry. But recently, commercial trawlers have begun to look into deeper and deeper waters to meet demand as supplies, placing species like the deepsea skate at risk (Cook & Zorzi, 2015). Currently the deepwater skate is listed at Data Deficient by the IUCN as population sizes and trends are unknown.

Skate Stats

Authority: Gilbert, 1896

Family: Arhynchobatidae, 41-45 species

Length: 5 feet ( 1.5 m)

Weight: Maximum weight unknown

Habitat: Continental shelves and slopes

Depth:  1300 – 9528 feet (396 – 2904 m)

Reproduction: Oviparous

Gestation: Unknown

Litter Range: Number of egg cases produced per reproductive cycle unknown

Home Range: Pacific Ocean from Northern Japan to the Bering Sea, south to Baja California, Mexico and the Galapagos Marine Reserve

Diet: Unknown

IUCN Data Deficient; taken as bycatch in commercial fisheries targeting deep water flatfishes.

(Cook, & Zorzi, 2015; Cerutti-Pereyra, 2018)

 

Just this week, the deepsea skate was the focus of a new paper in the Journal of the Ocean Science Foundation. The paper documents the first observation of this skate in the Galapagos Marine Reserve.

Thank you for checking out this week’s featured species. Be sure to check out last week’s Featured Species, the Tope Shark. This species has a sickening story that can impact your daily habits. Check it out.

The new Ocean For Sharks Shop is open! There’s handmade ocean inspired plush animals, canvas paintings, and of course my children’s book, Winifred the Wondrous Whale Shark, available in print and PDF. Be sure to stop by. Remember proceeds benefit shark research and conservation with a donation to Project AWARE!

As always, remember you can make a difference for marine ecosystems by contacting your Congress man or woman and telling them that you care about the quality of our waters! Sharks, rays, and other marine organisms cannot speak or be represented in Congress. They need your voice. Get involved and stand up for sharks. Until next time finatics!

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Featured Image Source

NOAA/MBARI (Photographer). (2002 May 20). Deepsea Skate (Bathyraja abyssicola) on the Davidson Seamount at 2373 meters depth [Digital Image]. Retrieved from https://commons.wikimedia.org/

Literature Cited

Cerutti-Pereyra, F., Yánez, A. B., Ebert, D. A., Arnés-Urgellés, C., Salinas-De-León, P., Darwin, C., & Ayora, P. (2018). New record and range extension of the Deepsea Skate, Bathyraja abyssicola (Chondrichthyes: Arhynchobatidae), in the Galapagos Islands. Journal of the Ocean Science Foundation, 30, 85–89.

Cook, S.F. & Zorzi, G.D. 2015. Bathyraja abyssicola. The IUCN Red List of Threatened Species 2015: e.T2636A80673712. http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T2636A80673712.en

Ebert, D. A. (2003). Sharks, Rays, and Chimaeras of California. California Natural History Guides (Vol. 71). London: University of California Press.

Ebert, D. A., & Compagno, L. J. V. (2007). Biodiversity and systematics of skates (Chondrichthyes: Rajiformes: Rajoidei). Environmental Biology of Fishes.

Ebert, D. A., & Davis, C. D. (2007). Description of skate egg cases (Chondrichthyes: Rajiformes: Rajioidei) from the eastern North Pacific. ZOOTAXA, 1393, 1–18.

Frisk, M. G. (2010). Life history strategies of Batoids. Sharks and Their Relatives II: Biodiversity, Adaptive Physiology, and Conservation, (Nefsc 1999), 283–307.

Klimley, A. P. (2013). The biology of sharks and rays. University of Chicago Press.

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