The Role of Bone Density in Structuring Prehistoric Salmon Bone Assemblages

Archaeologists working in north-western North America often suggest that the low frequency of salmon cranial elements and abundance of vertebrae in prehistoric deposits reflects the cultural use of stored fish. While empirical documentation of salmon storage is certainly important, a variety of noncultural factors, particularly bone density, should be considered in interpreting body part frequencies. Bone densities of representative cranial and postcranial elements from 10 chinook salmon (Oncorhynchus tshawytscha) were measured using X-ray absorptiometry. Except for the otolith, most cranial elements have lower densities than postcranial bones. The role of bone density in structuring prehistoric salmon assemblages is explored through comparisons of density measures with element survivorships in three archaeological assemblages with low cranial element survivorship. The scarcity of cranial elements in two of the assemblages is best explained by density-mediated destruction, while cultural processing probably accounts for the dearth of head bones in the third assemblage.