Archaeologists and resource managers are starting to recognize the value of studying ancient cultures for examples of how resources have, and have not, been sustainably utilized in the past as a way of understanding current trends in environmental degradation. These studies do not provide sweeping generalizations about aboriginal resource use but, rather, identify the range of conditions under which sustainable harvests may be possible. The hypothesis of sustainable harvests must be tested using variables that can be measured equally well in ancient (e.g., archaeological) and modern contexts.

These factors are carefully considered in this analysis of pinniped (seal and sea lion) remains from two archaeological sites on the eastern North Pacific (ENP) coast, where pinnipeds have been hunted for millennia. Reconstruction of the age composition, or harvest profile, of Callorhinus ursinus at the Ozette Village Site, Washington, shows that males and females of all ages were harvested, and supports the hypothesis that it was done so sustainably for over 500 years. After this period of apparent stability, C. ursinus abandoned local breeding colonies in the early historic period. In contrast, harvests of this species at the Moss Landing Hill Site, California, primarily targeted young of the year, and sub-adult and adult females. While this harvest is also inferred to have targeted a local breeding colony, C. ursinus appear to have been extirpated nearly 2000 years earlier at Moss Landing than at Ozette.

The causes of these extirpations are not known, but the timing does not correspond well with known climatic changes, suggesting that subsistence, and perhaps commercial, hunting may have played a role. These examples underscore the need to recognize that patterns of resource use are highly variable – different cultures have had varying levels of effects on economically important species, and these effects have varied temporally, spatially, and taxonomically.