Pottery produced by mobile hunter-gatherer-fisher groups in the northeast European forest zone is among the earliest in Europe. Absolute chronologies, however, are still subject to debate due to a general lack of reliable contextual information. Direct radiocarbon dating of carbonized surface residues (“foodcrusts”) on pots can help to address this problem, as it dates the use of the pottery. If a pot was used to cook fish or other aquatic species, however, carbon in the crust may have been depleted in 14C compared to carbon in terrestrial foods and thus appear older than it really is (i.e. showing a “freshwater reservoir effect,” or FRE). A connected problem, therefore, is the importance of aquatic resources in the subsistence economy, and whether pots were used to process aquatic food. To build better chronologies from foodcrust dates, we need to determine which 14C results are more or less likely to be subject to FRE, i.e. to distinguish crusts derived mainly from aquatic ingredients from those composed mainly of terrestrial foods. Integrating laboratory analyses with relative chronologies based on typology and stratigraphy can help to assess the extent of FRE in foodcrust dates. This article reports new 14C and stable isotope measurements on foodcrusts from six Stone Age sites in central and northern European Russia, and one in southeastern Estonia. Most of these 14C results are not obviously influenced by FRE, but the isotopic data suggest an increasing use of aquatic products over the course of the 6th and 5th millennia cal BC.