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Yes, Virginia, Walleye Pollock is Gadus chalcogrammus

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juevnile walleye pollock
A juvenile walleye pollock, Gadus chalcogrammus. Photo by Ingrid Spies.

The recent change of the scientific name of Walleye Pollock from Theragra chalcogramma to Gadus chalcogrammus has created some consternation among those of us working with this species on nearly a daily basis. The decision to change the generic assignment came about through extensive genetic studies that examined the number of species and evolutionary relationships among the cods (e.g., Coulson et al., 2006; Teletchea et al., 2006; Carr and Marshall, 2008). In all of these studies, Walleye Pollock was definitively placed in an evolutionary lineage that included the Pacific, Atlantic, and Greenland Cods (Gadus macrocephalus, G. morhua, and G. ogac). The data also indicated that Theragra is more closely related to G. morhua than the other cod species, rather than outside Gadus in a separate lineage. Morphological studies have been ambiguous, the position of Theragra left unresolved among other gadid genera (Dunn, 1989; Teletchea et al., 2006). Nomenclature should be congruent with our best hypothesis of evolutionary relationships, and to recognize this relationship a nomenclatural decision needed to be made. Authors (Coulson et al., 2006; Carr and Marshall, 2008) chose to include the Gadus and Theragra cod lineages together in the single genus Gadus, rather than remove Gadus morhua from Gadus in order to retain Theragra for Walleye Pollock.

A genus name and species name must agree in gender, according to International Code of Zoological Nomenclature (ICZN, 1999). Thus, when a species is moved to a new genus, an emendation of the species name is often required. Because Gadus is masculine, chalcogramma, the feminine form agreeing with Theragra, must be changed to chalcogrammus. Thus, Gadus chalcogrammus is the new name for Walleye Pollock. When citing the author of the name as required in some publication outlets, the correct citation is Gadus chalcogrammus Pallas, 1814 (not Pallas, 1811, as proposed by Carr and Marshall [2008] and Roa-Varón and Orti [2009]). This change has been recognized in the newest edition of the American Fisheries Society Common and Scientific Names of Fishes (2013), the standard followed by the NMFS Scientific Publications Office.

By James W. Orr and Duane E. Stevenson

Literature cited

ICZN (International Commission on Zoological Nomenclature). 1999. International Code of Zoological Nomenclature, 4th edition. The International Trust for Zoological Nomenclature, The Natural History Museum, London.

Carr, S. M., and H. Dawn Marshall.  2008.  Phylogeographic analysis of complete mtDNA genomes from Walleye Pollock (Gadus chalcogrammus Pallas, 1811) shows an ancient origin of genetic biodiversity. Mitochondrial DNA 19:490-496.

Coulson, M. W., H. D. Marshall, P. Pepin, and S. M. Carr.  2006.  Mitochondrial genomics of gadine fishes: implications for taxonomy and biogeographic origins from whole-genome data sets. Genome 49:1115-1130.

Dunn, J. R. 1989. A provisional phylogeny of gadid fishes based on adult and early life-history characters, pp. 209-235. In D. M. Cohen (ed.), Papers on the Systematics of Gadiform Fishes. Natural History Museum of Los Angeles County Science Series 32.

Lawrence M. Page, Héctor Espinosa-Pérez, Lloyd T. Findley, Carter R. Gilbert, Robert N. Lea, Nicholas E. Mandrak, Richard L. Mayden, and Joseph S. Nelson. 2013. Common and Scientific Names of Fishes from the United States, Canada, and Mexico, 7th edition. American Fisheries Society Special Publication 34. 243 p.

Pallas, P. S. 1814. Zoographia Rosso-Asiatica, sistens omnium animalium in extenso Imperio Rossico et adjacentibus maribus observatorum recensionem, domicilia, mores et descriptiones anatomen atque icones plurimorum. 3 vols. [1811–1814]. Petropoli. v. 3: i–vii + 1–428 + index (I–CXXV), Pls. 1, 13, 14, 15, 20 and 21.

Roa-Varón, A., and G. Orti. 2009. Phylogenetic relationships among families of Gadiformes (Teleostei, Paracanthopterygii) based on nuclear and mitochondrial data. Molecular Phylogenetics and Evolution 52:688-704.

Teletchea, F., V. Laudet, and C. Hänni.  2006.  Phylogeny of the Gadidae (sensu Svetovidov, 1948) based on their morphology and two mitochondrial genes. Molecular Phylogenetics and Evolution 38:189-199.


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