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Skates of Alaska Research

photo of Alaska skates
(Top to bottom: Raja binoculata,  
Bathyraja parmifera
)

The fish family Rajidae, commonly known as skates and rays, includes about 280 species of primarily benthic fishes found throughout the world’s oceans from tropical to cold temperate latitudes. At least 14 species of skates are known to occur in the Gulf of Alaska, Aleutian Islands, and Bering Sea from the 8 m to depths of over 1500 m. Many of these species are widely distributed, with ranges extending south along the coast of North America as well as into the western North Pacific, Sea of Okhotsk, and Sea of Japan.

Alaska’s skate fauna includes representatives of two genera: Raja and Bathyraja. The genus Raja, commonly known as the “stiff-snout” skates because they have a robust rostral cartilage, includes approximately 30 species worldwide and a North Pacific assemblage of 6 species ranging from the Gulf of California to the Bering Sea and into the western North Pacific. This North Pacific Assemblage is thought to be a cluster of closely related species and will probably be recognized as a separate genus in the future.

The genus Bathyraja, also known as the “soft-snout” skates due to their flexible rostral cartilage, includes over 40 species distributed throughout the world’s oceans. Bathyraja is the most broadly distributed and most diverse of all the skate genera, and the greatest diversity of Bathyraja occurs in the North Pacific. Most of Alaska’s skate species are included in this genus, although some authors include one or two of the species in the genus Rhinoraja. In general, members of the genus Bathyraja tend to be smaller and inhabit deeper waters than species of Raja.

The current level of interest in skate biology has provided impetus for a number of projects at the AFSC (see current research links below) including the report of a new species of skate from the Aleutian Islands (B. mariposa) and a review of species related to the Alaska skate (B. parmifera), as well as a report of the deepwater species B. abyssicola and Amblyraja badia new to Alaska. The AFSC’s Age and Growth Program began ageing Raja and Bathyraja species in 2003, and since then has produced a skate ageing manual as well as new techniques using vertebra for ageing skates in the Southern Alaska Peninsula. Research efforts also include the study of the reproductive behavior of the Alaska skate and Aleutian skate with focus on the characterization of skate nursery areas and approaches for nursery conservation in the southeastern Bering Sea. A molecular assay is being developed to use to identify skates on the basis of tissue samples. The AFSC is also collaborating on reproductive and life history studies on skates with the Pacific Shark Research Center at Moss Landing Marine Laboratory. Other AFSC research efforts include estimating capture probability of a survey bottom trawl for Bering Sea skates.

As we continue to refine and improve our ability to identify skates in the field, our ability to conduct scientifically rigorous investigations on the skate populations of Alaska improves dramatically. Ultimately, these studies augment the agency’s ability to provide effective stewardship of Alaska’s marine resources.


For more skate images see the "Skates of Alaska" poster by D. E. Stevenson, and J. W. ORR  (.pdf, 2.1 MB).
 

Recent Skate Publications, Poster Presentations, & Research Activities

  • Molecular systematics of the skate subgenus Arctoraja (Bathyraja: Rajidae) and support for an undescribed species, the leopard skate, with comments on the phylogenetics of Bathyraja.
    SPIES, I. B., D. E. STEVENSON, J. W. ORR, and G. R. HOFF. 2011. Molecular systematics of the skate subgenus Arctoraja (Bathyraja: Rajidae) and support for an undescribed species, the leopard skate, with comments on the phylogenetics of Bathyraja. Ichthyol. Res. 58:77-83. 
     
  • Bathyraja panthera, a new species of skate (Rajidae: Arhynchobatinae) from the western Aleutian Islands, and resurrection of the subgenus Arctoraja Ishiyama.
    ORR, J. W., D. E. STEVENSON, G. R. HOFF, I. SPIES, and J. D. McEACHRAN. 2011. Bathyraja panthera, a new species of skate (Rajidae: Arhynchobatinae) from the western Aleutian Islands, and resurrection of the subgenus Arctoraja Ishiyama. NOAA Prof. Pap. NMFS 11, 50 p. (.pdf, 8.92 MB).  Online.
     
  • Identification of skate nursery habitat in the eastern Bering Sea.
    HOFF, G. R. 2010. Identification of skate nursery habitat in the eastern Bering Sea. Mar. Ecol. Prog. Ser. 403:243-254. (.pdf, 1.04 MB).  Online.
     
  • Observer-reported skate bycatch in the commercial groundfish fisheries of Alaska.
    STEVENSON, D. E., and K. A. LEWIS. 2010. Observer-reported skate bycatch in the commercial groundfish fisheries of Alaska. Fish. Bull., U.S. 108:208-217. (.pdf, 919 KB).  Online.
     
  • Skate Nursery HAPC Designation in the Eastern Bering Sea
    By:  GERALD HOFF, MATT EAGLETON
    Conference:  Alaska Marine Science Symposium, Anchorage, AK, Jan 2014
    (2014 poster, .pdf, 6.28 MB)   Online.

     
  • Skate Nursery Sites as Habitat Areas of Particular Concern (HAPC)
    By:  GERALD HOFF
    Conference:  Western Groundfish Conference (17th), Seattle, WA., Feb 2012
    (2012 poster, .pdf, 1.99 MB)   Online.

     
  • Preliminary Life History Variability of Longnose Skate (Raja rhina) Across Two Large Marine Ecosystems: Gulf of Alaska and California Current System
    By:  CHRISTOPHER GBURSKI, THOMAS HELSER, VLADLENA GERTSEVA, JACQUELYNNE KING, DAVID EBERT
    Conference:  Western Groundfish Conference (17th), Seattle, WA., Feb 2012
    (2012 poster, .pdf, 2.5 MB)   Online.

     
  • Estimating Area of Skate Nursery Habitat
    By:  GERALD HOFF, HANUMANT SINGH, JARED GUTHRIDGE, OLAV ORMSETH
    Conference:  Alaska Marine Science Symposium, Anchorage, AK, Jan 2010
    (2010 poster, .pdf, 3.79MB)   Online.

     
  • Preliminary Results on the Age Validation of Big Skate (Beringraja binoculata) and Longnose Skate (Raja rhina) using Bomb-Derived Radiocarbon

  • Preliminary Life History Variability of Longnose Skate (Raja rhina) Across Two Large Marine Ecosystems: Gulf of Alaska and California Current System

  • Additional publications, posters, and reports.
     

photo of Alaska skates  
(left to right: Bathyraja minispinosa, B. violacea, B. mariposa)


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