Age and growth of the roughtail skate Bathyraja trachura (Gilbert 1892) from the eastern North Pacific

  • Chanté D. DavisEmail author
  • Gregor M. Cailliet
  • David A. Ebert
Special Issue Skates


This study provides the first published age estimates for the roughtail skate, Bathyraja trachura. Age and growth characteristics of B. trachura, a poorly-known deepwater species, were determined from samples collected along the continental slope of the contiguous western United States. A new maximum size was established at 91.0 cm TL. Age was determined using a traditional structure (vertebral thin sections) with widespread application on multiple skate species and a non-lethal structure (caudal thorns) recently used for age analysis on skate species. Caudal thorns were determined not to be a useful ageing structure for this species based on poor precision and significantly lower age estimates when compared to age estimates from vertebral thin sections. The best model for describing growth of B. trachura was the two parameter VBGF, assuming annual vertebral band deposition and using length-at-age data. Although females grew slower and reached a larger maximum size than males, their growth was not statistically different (ARSS; P = 0.90); therefore, data were pooled (L = 99.38, k = 0.09). Annual band deposition was found to be a reasonable assumption for this species, but has yet to be validated. The maximum age estimated for B. trachura was 20 years for males and 17 years for females using vertebral thin sections.


Vertebral thin sections Caudal thorns Age estimation Elasmobranch Skate 



We thank Guy Fleisher, Keith Bosley, Erica Fruh, Aimee Keller, Victor Simon, and Dan Kamikawa NMFS/Northwest Fisheries Science Center for collecting samples during their yearly groundfish cruises in the eastern North Pacific. We also thank John Cusick and observers at the West coast Groundfish Observer Program for collecting samples throughout the year. We are grateful for the students and staff at Pacific Shark Research Center (PSRC) at Moss Landing Marine Laboratories who helped process and prepare samples for analysis, especially Joe Bizzarro, Colleena Perez, and Wade Smith. Funding for this research was provided by NOAA/NMFS to the National Shark Research Consortium and Pacific Shark Research Center, the National Sea Grant College Program of the U.S. Department of Commerce’s National Oceanic and Atmospheric Administration under NOAA Grant no. NA04OAR4170038, project number R/F−199, through the California Sea Grant College Program and in part by the California State Resources Agency. Samples were collected under IAUCUC protocol #801.


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Copyright information

© Springer Science+Business Media, Inc. 2007

Authors and Affiliations

  • Chanté D. Davis
    • 1
    Email author
  • Gregor M. Cailliet
    • 1
  • David A. Ebert
    • 1
  1. 1.Moss Landing Marine LaboratoriesPacific Shark Research CenterMoss LandingUSA

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