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Journal of Archaeological Science

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Chinook salmon -- Identification, Conservation biology, Animal remains (Archaeology) -- Analysis, Vertebrae -- Morphology


Remains of anadromous Pacific salmon and trout (genus Oncorhynchus) are common in archaeological sites from California to Alaska; however, morphological similarity generally precludes species identification, limiting the range of questions that salmonid remains can address in relation to past human use and ongoing efforts in conservation biology. We developed a relatively simple, rapid, and non-destructive way to classify salmon and trout vertebrae from archaeological contexts to species using length, height and the ratio of length to height. Modern reference material was obtained from all seven anadromous Oncorhynchus species native to the west coast of North America. A minimum of ten adult Chinook (Oncorhynchus tshawytscha), chum (O. keta), coho (O. kisutch), pink (O.gorbuscha), and sockeye salmon (O. nerka) and cutthroat (O. clarki clarki) and steelhead trout (O. mykiss) were skeletonized and vertebra length and height were measured. Morphometric analyses compared species classification success based on Linear Discriminant Analysis (LDA), Classification and Regression Trees (CART), and randomForest, with CART performing the best. Classification analyses used all seven species individually, but because of considerable overlap among several species we also conducted analyses on four species groupings. We assigned Chinook salmon and cutthroat to their own groups based on their dissimilarities from each other and the other species. The remaining species were divided into two group complexes (a) chum, coho, and steelhead; and (b) pink and sockeye. When we grouped species according to similar morphology, CART overall success rates increased, ranging from 92 to 100%. Individual species with the highest successful classification rates using CART were Chinook salmon and cutthroat, from 92 to 100%, respectively. We applied our classification to an assemblage of ancient (1000 to 3000 year old) salmonid vertebrae from the Swiftwater Rockshelters excavations on the upper Wenatchee River in Washington State, U.S.A.


NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Archaeological Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Archaeological Science, 38(1), 136-146. DOI: 10.1016/j.jas.2010.08.020



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