4. Discussion

4.1 Presence of seals in the Baltic Sea

The presence of ringed, grey and harp seals in the Baltic Sea is related to the post-glacial development of the Baltic Sea basin and linked to climatic fluctuations during the middle Holocene (Lepiksaar 1986; Lõugas 1997; Ukkonen 2002; Sommer and Benecke 2003; Storå and Lõugas 2005; Schmölcke 2008). The ringed seal was the first species that entered and reproduced in the Baltic Sea basin in a very early stage of its formation, the Yoldia Sea stage, when marine water entered the Baltic basin for the first time and a brackish environment was established (Lõugas 1997; Ukkonen 2002; Schmölcke 2008). During the next stage, the Ancylus Lake, the connection to the Atlantic Ocean was closed after the glacio-isostatic land uplift of Scandinavia. Subsequently, the ringed seal remained the only seal species present in the Baltic Sea, i.e. in the Gulf of Bothnia and Finland until the late Atlantic climatic period (Ukkonen 2002; Sommer and Benecke 2003; Aaris-Sørensen 2009). Appropriate environmental conditions for seals in the Baltic were established within the next millennia, known as the Littorina stage, when fluctuations of the Baltic Sea with saline water from the Atlantic Ocean, created gradually more marine conditions and a permanent connection between the Baltic Sea and the Atlantic Ocean was established. The frequencies of subfossil finds from harp and grey seals increased throughout the Baltic Sea after the Littorina Transgression, and showed that these animals started to reproduce in the Baltic Sea during the last stage of its formation.

Harp seal bones start to appear frequently during the Early Subboreal climatic period in several Swedish archaeological coastal areas (Fredén 1975; Ukkonen 2002; Aaris-Sørensen 2009). Their occurrence in the Baltic Sea during this period is linked to the presence of a permanent harp seal population (Storå 2001a; Storå and Ericson 2004; Storå and Lõugas 2005). According to direct radiocarbon dates, the Baltic Sea harp seal population did not become established until the Subboreal climatic period (Bennike et al. 2008). In fact, both direct dating and relative chronology revealed by the archaeological contexts show a regular presence of harp seals in the Baltic Sea between 4000–1800 cal BC (Storå and Lõugas 2005). The harp seal remains found in Neustadt are dated according to the archaeological context between 4400-3800 cal BC and thus belong to the oldest established harp seal population in the Baltic region (Glykou 2011b). Later, during the Neolithic Pitted Ware Culture, harp seals appear in very high frequencies in numerous sites mainly on Gotland, Åland, as well as in the eastern Baltic (Storå 2001a; Ukkonen 2002; Storå and Lougas 2005). In most of these cases the intensive seal exploitation is linked to the occurrence of harp seal breeding grounds in these regions (Storå and Ericson 2004).

Seal-dominated faunas are known from several early and middle Mesolithic occupation sites in the northern Baltic, mainly in Finland, where the exploited seal species consisted of ringed and grey seals (Lindqvist and Possnert 1997; Ukkonen 2002; 2004). From the south-western Baltic, seal remains are evident in numerous archaeological deposits but always represented by just a few bones in each case (e.g. Møhl 1970; 1971; Andersen 1995; Enghoff 2009; 2011; Trolle 2013). According to the relative frequency of seals in Neustadt, hunting of harp and grey seals was a substantial part of the economy, representing the oldest evidence of extensive seal exploitation from the south-western Baltic Sea region. Another submerged site, also dated to the late Mesolithic Ertebølle culture, with high frequencies of seal bones (approximately one-third of the total faunal remains) derives from the site Timmendorf-Nordmole I in the Wismar Bight at the Mecklenburg Bay (Schmölcke et al. 2007). To what extent this new feature in the economies of the terminal Mesolithic in the south-western Baltic Sea region indicates a conscious change in the economy from terrestrial to marine, will be discussed below.