Fishing for Dog Food: Ethnographic and Ethnohistoric Insights on the Freshwater Reservoir in Northeastern North America

Abstract

A review of current research reveals multiple lines of evidence suggesting that no single freshwater reservoir offset (FRO) correction can be applied to accelerator mass spectrometer (AMS) ages obtained on carbonized food residue from cooking vessels. Systematically evaluating the regional presence, magnitude, and effects of a freshwater reservoir effect (FRE) is a demonstrably difficult analytic problem given the variation of ancient carbon reservoirs in both space and time within water bodies, and which should be performed in advance of AMS assays. In coastal and estuarine contexts, a priori partitioning FRE from known marine reservoir effects (MRE) is also necessary to eliminate potential mixed effects. Likewise, any FRE varies based on the proportional mix of resources producing the residues and the ancient carbon uptake of those products. Processing techniques are a significant component of assessing potential FRE, and each pot/cooking vessel is therefore an independent context requiring analytic evaluation. In northeastern North America, there is little ethnohistoric/ethnographic evidence for fish boiling/stewing in ceramic cooking vessels; rather, fish were more often dried, smoked, or cooked for immediate consumption on open fires. Assays of fatty acids extracted from prehistoric vessel fabrics even on known fishing sites reveals no evidence for fish in the food mix. These observations suggest that the likelihoods of FRE in carbonized food residue in northeastern North America is therefore low, and that assays potentially suffering from FRO are minimal. In turn, this suggests that AMS ages from carbonized food residues are reliable unless analytically demonstrated otherwise for specific cases, and should take primacy over ages on other associated materials that have historically been employed for critical threshold chronological events.

Freshwater reservoir offsets and food crusts: Isotope, AMS, and lipid analyses of experimental cooking residues

“…However, concern remains as to the accuracy of radiocarbon dates obtained on cooking residues, especially when those dates do not match accepted regional chronologies [ 10 – 12 ]. Of primary importance for investigating FROs is understanding how different resources contribute carbon to residue formation, and the variability of ancient carbon sequestered in freshwater bodies and as a result, aquatic organisms both spatially and temporally [ 13 – 15 ].…”

Woodland Pottery Function, Cooking, and Diet in the Upper Great Lakes of North America

“…Ethnographic sources document that boiling fresh fish was usually reserved for rendering fish oil; more commonly, fresh fish were spit roasted or dried, and dried/smoked fish, which may have a lower fat content, was sometimes added to stews (Hilger 1951; Rogers 1962;Densmore 1979;Tooker 1991). Lovis and Hart (2015) point out that 224 SUSAN M. KOOIMAN among indigenous groups across northeastern North America spit roasting fish was far more common than cooking fish in pots. Occupants of Naomikong Point and Sand Point may not have focused their energy on rendering fish oil but rather on processing for storage the large numbers of fish brought in during the fishing seasons and spit roasting fresh fish for immediate consumption.…”

Surplus Production and Marine Resource Use in the North Norwegian Iron Age

“…A study from North America's north-eastern interior of the freshwater reservoir effect in carbonized food residue has also indicated that the reservoir effect is minimal. In this study, the AMS ages were deemed reliable unless analytical reasons demonstrated the opposite in a specific case (Lovis and Hart, 2015, also compare to conclusions in Mangerud et al, 2006 based on marine samples).…”