Within the Upper Klamath Basin, Oregon, the native status of anadromous salmonids (Oncorhynchus spp.) has been a long standing question. Ongoing efforts to establish if these fish were native to the region prior to the construction of the Copco I Dam on the Klamath River (c.1917) have relied on sparse, contradictory and sometimes unreliable historic documentation and informant testimony. Current restoration projects with very high financial and social costs necessitate accurate and reliable data on salmonid species which once called the region home. Often, archaeolofaunal remains present a novel way to determine species present in an area prior to major habitat losses. This project analyzed fish remains from five previously excavated archaeological sites within the Upper Klamath Basin to determine which salmonid species were present prior to dam construction. A total of 5,859 fish remains were identified to at least taxonomic order using morphological distinctions. Site collections were dominated by those of catostomids (suckers) and cyprinids (minnows). Archaeological deposits at these sites dated as far back as approximately 7,500 BP but were primarily from the last 2,000 years. Only eighty-one salmonid remains were observed within the sites included in this project. The low frequency of salmonid remains in these sites may be the result of cultural and/or natural processes such as density mediated attrition and archaeological sampling. Of these 81 specimens, 38 were subjected to mtDNA analysis for species identification. Seven specimens did not yield DNA sufficient for species identification, six specimens were identified as O. tshawytscha (Chinook) and the remaining 25 specimens were identified as O. mykiss (steelhead or redband trout). Geochemical analysis was used to determine the life history of the fish represented by the remains within these collections. Strontium Calcium (Sr:Ca) ratios were measured on twenty-eight specimens. Three specimens were determined to be from freshwater resident fish and 25 were determined to be from anadromous fish. The specimens which were genetically identified as O. tshawytscha were all determined to be anadromous. Of the 18 specimens which were identified as O. mykiss and were subjected to geochemical analysis two were from freshwater resident fish and sixteen were from anadromous fish. Four samples were not characterized genetically but were subjected to geochemical analysis; three of these were determined to be from anadromous fish and one from a freshwater resident fish. Thus, the remains of anadromous O. mykiss and O. tshawytscha were identified in archaeological deposits predating construction of the Copco I dam in the Upper Klamath Basin While the genetic and geochemical analyses confirm the presence of skeletal remains from anadromous salmonids in the Upper Klamath Basin archaeological sites prior to dam construction these remains may, represent fish caught elsewhere and traded in. Two hypotheses address the introduction of these fish remains into pre-dam archaeological deposits, either they were traded/transported in from elsewhere (Trade/Transport Hypothesis) or they were caught locally (Local Catch Hypothesis). Expectations linked to each of these hypotheses were generated using ethnographic information from across the Pacific Northwest, including modern testimony from the Klamath Basin. Fish heads were often removed soon after capture in order to reduce spoilage of the rest of the fish. Thus, assemblages with many head parts are probably the result of local catch while those without head parts are probably the result of trade and/or transport. Two approaches were used to estimate the extent to which fish heads were deposited in sites. Basic proportions of cranial to post cranial remains from two sites provided a varied picture and did not readily support either the Local Catch or Trade/Transport hypotheses. Evaluation using scaled proportions based on frequency of skeletal elements within the body (Minimum Animal Units) show that four of the five assemblages were dominated by cranial remains and therefore suggest these fish were locally caught. Small samples sizes make it difficult to rigorously evaluate the hypotheses, though the dominance of cranial remains suggests salmonids were taken locally. Together these data indicate that anadromous O. tshawytscha and O. mykiss were taken from waters within the Upper Klamath Basin prior to the construction of Copco I. This study has provided accurate and reliable data, using a novel approach, on which restoration efforts in the region can rely for proper species reintroduction and habitat restoration efforts.