Publication Date

Spring 2017

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Moss Landing Marine Laboratories

Advisor

Jonathan B. Geller

Keywords

Arhynchobatidae, Bathyraja, Redescription, Softnose Skate, Systematics

Subject Areas

Systematic biology; Zoology; Biology

Abstract

Softnose skates (Rajiformes: Arhynchobatidae: Bathyraja Ishiyama) are the most diverse genus of skates, with 54 described species, and are readily distinguishable from their congeners by their relatively uncalcified and flexible rostral cartilages. Six species of Bathyraja are considered valid in the eastern North Pacific, including: deepsea skate, B. abyssicola, Aleutian skate, B. aleutica, sandpaper skate, B. kincaidii, fine-spined skate, B. microtrachys, Pacific white skate, B. spinosissima, and roughtail skate, B. trachura. As with other skate genera, the eastern North Pacific Bathyraja lacks a well-supported phylogeny, which leads to issues with setting catch limits and creating management plans. This study identifies and formally describes the softnose skates species in the eastern North Pacific based on morphometric and meristic measurements and includes an Alaskan species, Bering skate, B. interrupta due to its close morphological relationship to B. kincaidii. Multivariate tests determined that significant differences existed between the study species. Parsimonious phylogenetic trees showed that B kincaidii represents the basal condition, with B. abyssicola and B. aleutica being the most derived species in the study. The synonymized species B. interrupta and B. kincaidii were shown to be separate, as were the synonymized species B. microtrachys and B. trachura. An improved Bathyraja phylogeny will hopefully assist fisheries managers in developing conservation policies and easing the impacts of deepsea fishing expansion.

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