Ancient DNA from Salmon Bone: a Preliminary Study

INTRODUCTION In the Pacific Northwest of North America, archaeological saImonid remains have great potential to inform on issues of prehistoric cultural use, salmonid paleobiology and past environments. One hindrance to using prehistoric salmonid remains has been the gross level of taxonomic identification generally achieved. Species diagnostic elements are rarely found in archaeological contexts. Recent breakthroughs in ancient DNA research using the polymerase chain reaction (PCR) suggest a new way to obtain specieslevel and possibly finer taxonomic information from prehistoric samples. Salmonid-specific primers were developed to target sholt, taxonomically informative regions of mitochondrial DNA. PCR amplifications of DNA extracted from modem salmonid muscle and bone samples were successful, demonstrating the utility of the primers and the presence of DNA in saImonid bone. PCRs on extracts from archaeological and noncultural surface bone deposits, ranging in age from 9000 to 20 years old, also were successful, although retrievable DNA was more fragmented and degraded than in modem bone and muscle tissue. Direct sequencing of amplified products from one ancient sample confirmed that the product was from Oncorhynchus and tentatively suggested that the sample was from o. nerka. Salmonid remains are found in hundreds of archaeological sites from California to Alaska, on the coast and along rivers in the interior, dating to the last 10,000 years. Such remains have great potential to inform on issues of prehistoric cultural use, salmonid paleobiology, and past environments (Schalk, 1977; Butler, 1993; Chatters et al., 1995; Matson and Coupland, 1995). However, a major hindrance to using archaeological salmonid remains to address such issues has been the gross level of taxonomic identifications generally achieved. In western North America, the dominant taxon in the family (in number of species and individuals) is Oncorhynchus, which is represented by seven species of salmon and trout. Unfortunately, based on skeletal morphology, only a few cranial elements are species diagnostic (Casteel, 1974; Gorschkov d aI., 1979) and these are recovered rarely from archaeological sites (probably because of preservation factors: Butler and Chatters, 1994). Archaeological