1. Introduction
Zooarchaeology is usually considered to be the study of animal bones found on archaeological sites. However, dead animals can leave behind many types of remains other than bones. This is particularly the case for invertebrates, some of which have a very hard and compact exoskeleton. One of the enduring kinds of remains, if well preserved, is the mollusc shell. Depending on the speed of deposition and the soil type, shells may be preserved very well or, on the contrary, may break quite easily. Direct disposal and immediate burial results in better preservation than first keeping remains in the open air and burying them later.
There are many examples of mollusc shells recovered from archaeological material, and most of these relate to shellfish (“shellfish” being a common name used for members of several families of bivalve molluscs). Campbell [
1] emphasizes the need to collect mollusc shells from archaeological sites, especially those of marine origin. Since marine molluscs do not occur in terrestrial habitats, the presence of their shells on archaeological sites is the result of human activity (not to be confused with the presence of shells in natural coastal sediments). Humans have gathered shellfish for many purposes, but mostly for food. Shells can be informative regarding subsistence, annual scheduling, the resources and habitats exploited, the effects of that exploitation on wild populations and exchange networks, the speed and efficiency of transportation, etc. [
1].
For example, in Denmark, a special kind of accumulation of waste from human activity, called a
køkkenmødding (“kitchen midden”), consists largely of mussel shells, indicating the heavy exploitation of mussels for human food, especially during the time of the Ertebølle Culture. Accordingly, the name “shell midden” is also used to refer to these ancient dumps [
2,
3,
4]. In Europe, shell middens can be found mostly along the Atlantic seaboard, but also at lakeshores, and date from the 5th–4th millennium BCE [
5]. Younger middens are also found, although in the eastern Baltic only one site—Riņņukalns in Latvia—has yielded a typical shell midden from the 4th–3rd millennium BCE [
6]. This accumulation contains only freshwater molluscs, which are available in the local Lake Burtnieki water system.
Another type of shell, often found in Iron Age and medieval find complexes, comes from the marine snail called the cowrie (
Cypraea (
Monetaria) moneta). This mollusc is most abundant in the Indian Ocean, and its shell was used worldwide as currency. It reached the eastern Baltic first by trade in the Viking Age, approximately the 7th–10th century, and there are numerous cowrie finds from burial sites of the 13th–15th century [
7] (p. 149), [
8] (p. 108).
None of the prehistoric assemblages from the eastern Baltic contain oyster shells; these appear only from medieval times onwards. European flat oyster (
Ostrea edulis Linnaeus) is a native oyster species of western European coastal waters. A few centuries ago, oysters populated the shallow, as well as deeper, offshore waters of the eastern Atlantic in great numbers. Particularly abundant beds of flat oysters occurred in the central part of the North Sea, including the Wadden Sea, but from the end of the 19th century, the oyster populations suffered from heavy overexploitation [
9,
10]. Oysters were also cultivated, a practice that is attested in Italy as far back as the 1st century AD and developed elsewhere as well, especially in later times, after the wild populations had diminished due to overexploitation [
11,
12]. As the conditions in the Baltic Sea (including excessively low salinity and large temperature fluctuations in the brackish coastal zone) are not suitable for oysters [
12], they cannot live in this sea; although, there have been some unsuccessful attempts to introduce oysters into the southern Baltic [
13] (p. 62). Therefore, all finds of oyster shells in the eastern Baltic can be considered imports.
Besides the finds of oyster shells, other imported shellfish have also been identified in Estonian archaeological material. Not numerous, although still represented, the blue mussel (
Mytilus edulis) and the scallop (great Atlantic scallop,
Pecten maximus, and/or the Mediterranean Jacob’s scallop,
Pecten jacobaeus) have been recorded. Although the scallop finds are usually associated with the pilgrimage to Santiago de Compostela in north-western Spain, and in most cases the association is correct, some of the recovered fragments seem to be ordinary food waste. However, in view of the low number of such fragments in the archaeological material and the most typical find contexts (ecclesiastical sites, burial sites), culinary purpose is usually excluded. A few specimens of cockle (
Cerastoderma sp.), whelk (
Buccinum undatum), limpet (
Patella vulgata) and clam (Veneridae) shells have also been found, all of them considered as imports to the eastern Baltic [
14] (see
Supplementary Materials). Only the shells of the freshwater mussels living in rivers and lakes are considered to be of local origin.
In Germany, on the coast of the Wadden Sea, the marketing of oysters began in the 13th century AD, when the North Frisians brought fish and oysters by boat to the market in Hamburg [
15]. However, there are no indications that oysters were traded or transported inland at that time [
13] (p. 60). In England, marketing to, for example, the west coast of Schleswig, Germany began in the 11th century (
ibid.), although local marketing had already started in southern Britain during Roman times [
16]. An organized German oyster fishery first developed off the islands of Sylt and Föhr on the coast of the Wadden Sea in the 16th century, still under Danish overlordship, and became an important economic activity in the 17th century. An interesting fact is mentioned by Hansen [
15]: in the 17th century, Swedish merchant ships repeatedly robbed North Frisian fishermen of their catch when sailing to market in Hamburg. Hamburg was an important trading centre at that time, and most of the catch was marketed there, oysters sometimes being shipped as far as Hungary and Russia [
13] (pp. 61–62). While the trade to Hungary required some transport over land, north-eastern Russia, especially St Petersburg, was accessible via the Baltic Sea. The trade to the eastern Baltic also involved the harbours in Estonia, Latvia and Lithuania (see
Figure 1).
The aim of this article is to combine archaeological and historical evidence on oyster import from the eastern Atlantic, primarily the North Sea, to the eastern Baltic, as well as oyster marketing in late medieval and early modern times, that is, from the 15th to the 19th century. The focus is on oyster shell finds in Estonia, the dietary importance of oysters and whether they were being consumed by the nobility and/or ordinary people. Where our evidence allows, we discuss the origin of the oysters, how they were transported over the Baltic and how they were prepared for the long-distance journey. In this paper, we present the first approach to oyster shell assemblages found in Estonian archaeological collections and combine this information with written sources. The idea is also to document the earliest archaeological evidence and historical record of oysters in the eastern Baltic, particularly in Estonia.
3. Historical Evidence of Oysters in Estonia
From the second half of the 17th century onwards, oysters appear regularly in various archival sources [
29] (p. 16); [
30] (p. 68). Quite certainly, the first oysters arrived in Estonia before this, but initially their import was scanty and random, and they had no impact on local gastronomy. Considering the fact that oysters were not stored, even for the most grandiose feasts in medieval Tallinn, which was the biggest and wealthiest Hanseatic town of Estonia, it is highly likely that oysters were not being imported to Estonia at that time. The long period of the Livonian War in the second half of the 16th century, and further conflicts at the beginning of the 17th century, brought impoverishment and famine; hence, the times were unsuitable for enjoying culinary pleasures and luxurious foods. Only after the stabilization of the political and economic situation could people pay attention to new developments in gastronomy and enlarge the assortment of imported foods.
Various account books preserved in Estonian archives provide information about the import and consumption of shellfish in the early modern period. Overseas trade in the 17th and 18th centuries mainly took place through the harbours of Tallinn, Narva and Pärnu. Therefore, customs books contain essential data on shellfish import (for example, on the amount of import, prices of goods and so forth) but they also reveal the arrival time and departure port of seagoing ships. Diverse feast accounts from the Tallinn City Archives provide more specific information about the consumption of oysters.
Nevertheless, oyster consumption always remained limited in Estonia. Imported shellfish were valued only by wealthy citizens and the nobility. Oysters were consumed as a delicacy and luxury food on special occasions only. However, according to written sources the local elite consumed shellfish in quite remarkable quantities. Oysters appear in account and customs books throughout the year, including the summer period. For example, on 8 July 1669, at a feast given in Tallinn in honour of state counsellor Lars Fleming, three big and four small barrels of oysters were also served, among other delicacies [
31] (p. 255). In the 17th and 18th centuries, oysters were obligatory at the feast of St Thomas, given by the Tallinn Town Council [
31] (p. 44, 46, 186, etc.). For that feast 100–200 oysters were usually bought, which were most probably served with lemon [
31] (p. 48, 48v).
Already by the second half of the 17th century, eating oysters had become quite popular among the social elite in Estonia, and demand for shellfish increased. Oysters were mostly imported in small barrels and casks, but bigger vessels were sometimes also used. For example, in 1781, two and a half barrels contained as many as 3000 oysters [
32] (p. 24). It should be mentioned that accurate records were kept when selling and buying. In 1771, no less than 126836 fresh or raw oysters were imported to Tallinn [
33] (p. 412). In October 1682, Tallinn Town Council alone bought oysters seven times, in 10 small barrels altogether [
31] (pp. 4–5). Afterwards, the consumption of oysters spread to manors and small towns as well. Accounts and correspondence preserved from the second half of the 18th century illustrate how two big trading companies in Pärnu, Jacob Jacke and Company and Hans Diedrich Schmidt, supplied numerous manors in the surrounding counties, and some small towns, with shellfish [
34]. According to written sources, these were often fresh or raw oysters (
100 st frische östers) [
31] (p. 6v), which means that transporting them from the harvesting place to Estonia must have been very well organized, for otherwise the food could easily have become spoiled. It is known that oysters remain fresh for up to 10 days, or up to 8–12 weeks, if kept cool and closely packed [
35]. They could have simply been tightly packed in baskets or barrels to keep the valves tightly shut, preventing desiccation [
10]. This would have been enough time for the voyage across the Baltic Sea and sale in markets.
Oysters reached the consumers in Estonia not directly from their harvesting place but often through various intermediaries. Seagoing ships loaded with shellfish mostly arrived from Lübeck and Amsterdam. According to the customs books of Pärnu, in addition to merchants, ordinary people imported oysters as well, but only for personal use [
36] (p. 46). Usually, there is no information preserved in archival sources about the origin of oysters imported to Estonia, with the exception that, in October 1781, the customs book of Pärnu records that 400 Holstein oysters were imported from Lübeck [
32] (p. 24). According to information from the 19th century, in Schleswig-Holstein there were oyster beds near Amrum, Föhr, Hallig and Sylt, in north-western Germany [
37] (p. 68).
18th century customs books reveal that, in addition to fresh or raw (live) oysters, salted oysters (
gesaltzene Austern) and conserved (perhaps marinated) oysters (
eingemachte Austern) were being imported to Estonia [
38] (pp. 4, 35, 36). The conserved oysters were transported in small glass vessels (jars) (
10 Gläser eingemachte Austern), which indicates that they were preserved without shells [
39] (p. 7). At the same time, salted oysters were sold in barrels; hence, they were conserved with shells or at least half shells. The 18th century Baltic German commentator, August Wilhelm Hupel, wrote that oysters were popular with the German elite in Estonia, bringing a price of 4 roubles for 100 pieces [
33] (p. 461). Conserved shellfish (oysters and mussels) were also highly valued as imported goods. According to Hupel, foreigners also tried to cook local Estonian molluscs for meals, and regarded some of them as quite tasty. Nonetheless, local people were not ready to value them as food.
4. Discussion
Most of the archaeological oyster shells in Estonia come from archaeological assemblages dating approximately from the second half of the 17th, and up to the 18th, century. The oldest finds may be from the late 15th century; however, the find contexts are usually too vague to be absolutely certain. It is interesting to note that quite often the shells are accompanied by fragments of clay tobacco pipes—whether this is a marker indicating the site of a tavern/inn, or just evidence of feasting, needs further analysis in the future.
The broad analysis of the sites where the oyster shells have been recovered offers, by and large, just a few surprises. As expected, most of the data comes from the major urban centre of Estonia, Tallinn, which has been archaeologically investigated much more intensively than other places. Our database consists of 45 individual investigations that can be topographically divided into three main areas: three sites are situated in the upper town (Toompea, in Estonian), which was the administrative centre of the province, both during the period of rule by the Kingdom of Sweden (1561–1710) and under the Russian Empire (1710–1917). The upper town can also be regarded as the residential area of the nobility; although, in addition to the elite, people of lower social status (such as servants), as well as various craftsmen, also lived here. Next, there are nine sites in the heart of Tallinn, within the walled Hanseatic town, which was inhabited by very diverse strata of townsfolk. Last but not least, most of the oyster finds come from the various suburbs of the city, where 33 fieldwork projects have produced relevant material.
In general, the above-mentioned statistics are not surprising. First of all, research in the upper and lower town has been less extensive than in the suburbs, as the historical core of Tallinn is relatively well preserved. In addition to this, one has also to bear in mind that much of the urban waste of the town plots was not accumulated on the spot but was removed from the fortified centre of the town. Urban waste management is visible in the archaeological record in at least two ways: the collected muck was distributed on the fields and gardens of the suburban plots around the southern side of the town as a fertilizer (among other examples, perhaps most vividly described in [
40,
41]), or else the refuse deposits were taken to a designated area north of the walled town and used in the reshaping of the suburban townscape [
42]. Thus, the exact dating of the assemblages is, in most cases, difficult. The
intra muros finds are mainly from mixed layers, not from sealed contexts; the suburban material, on the other hand, is either thoroughly ploughed and/or comes from tertiary layers (e.g., refuse from unidentified town plots). Therefore, providing precise dates for the consumption of the oysters generally involves a strong element of subjectivity.
However, assessment of the associated artefacts from the same layers does offer at least some basis for interpretation. In the upper town, the earliest find complexes with oyster shells appear to date from the 17th century (e.g., material from 17 and 21/2 Toom-Kooli Street). The situation appears to be similar in the lower town, where, along with undatable contexts (heavily mixed layers or stray finds), there is evidence from two sites (9 Kooli Street and 52 Lai Street/5 Tolli Street) to suggest that the food waste is from the second half of the 17th century, and in one case (7 Aia Street/12 Uus Street), perhaps even from the first half of the 17th century. In the suburbs, the majority of this evidence can be associated with the 18th and 19th century, and in some cases, the late 17th century (e.g., Roosikrantsi Street, 7 Estonia Boulevard and 17 Põhja Boulevard/1 Soo Street) is not out of the question. Whether we are dealing here with suburban plots of higher echelons of the townsfolk (many had summer homes outside the city walls), or whether this should be interpreted as rubbish from the town centre, needs further analysis in the future.
There is one suburban area that needs extra attention: the Kalamaja suburbs, especially around Jahu Street in the north-western part of Tallinn. Two sites in this district, north of the town wall, have offered remarkably early dates for the consumption of oysters when compared with the overall data. At 5 Jahu Street, from the activity layers associated with a house of the early modern period, there are some oyster shells from the 17–18th century, and in one case, even the 16th century is a possibility. Still, since we do not have sealed and well-dated contexts here, we must be cautious about dating these finds to such an early period with absolute certainty. Then again, such an early date is perhaps not absolutely impossible, if we consider the collection unearthed across the street, at 6 Jahu Street. Here, a late medieval landfill with the peak of deposition around the 1480s [
42,
43] also yielded 43 oyster shells. Whereas most of the shells can be associated with later times, the 17–18th century, there are a couple of finds that might come from late 15th and early 16th century refuse deposits. At least based on the layer descriptions and associated artefacts, a later dating seems to be ruled out, yet the nature of the site (landfill) and the research method (salvage excavation) leaves plenty of room for speculation. Nevertheless, since these deposits also include other kinds of late medieval luxury food remains (such as walnuts) and items of higher social status, it is not completely out of the question that we may be dealing here with the earliest evidence of oyster consumption in Tallinn, if not in the eastern Baltic as a whole.
Moving now to Tartu, we find that the evidence from the second-largest town in Estonia does not add much to the variety of consumption patterns or relative chronology of the appearance of oysters in the archaeological record. The catalogued finds are comparatively evenly distributed across the townscape, with 19 sites in the town core and nine outside the former defence line, i.e., in the suburbs. The inner town collections are mostly from traditional consumer contexts (e.g., town plots) without any significant bias towards the highest strata of the townsfolk. Generally, the oyster finds are associated with artefacts of the late 17th to 18th century and later, and none of the registered find contexts seem to belong to earlier settlement phases. In one noteworthy exception, two oyster shells were found in a later 18th century burial vault inside St John’s Church, perhaps indicating disturbance of the chamber in the 19th–20th century.
The third largest collection of relevant finds comes from Pärnu, more precisely from the area of the former Hanseatic town, New Pärnu. Currently we have data on seven sites. The overall number of excavations with oyster finds is considerably broader but does not change the general impression obtained in the course of research for the present paper. In contrast to Tallinn and Tartu, all finds are from the town core, inside the medieval town walls, and not from historical suburbs. Chronologically, the majority of the collected oyster shells appear to have been discarded in the 18th century, and larger-scale consumption seems to begin in the late 17th century [
14]. Although none of the sites have revealed finds earlier than 1600 AD, there are general indications of oyster consumption in the late 16th century: in some cases, the assemblages were dominated by fragments of 16th century pottery and stove tiles, though it should be noted that these had been redeposited during the 17th century reconstruction of the townscape.
There is one find context that deserves separate attention: one of the most exceptional oyster assemblages studied thus far comes from 2 Munga Street in Pärnu. Here, inside a post-medieval log building, a wooden tub with a diameter of 60 cm was unearthed, which had been sunk into the floor of the log house [
44] (p. 13). More than 200 unopened oysters were collected from this tub, along with the lower part of a wine bottle. Based on the bottle, the collection of oysters should be dated to the latter part of the 18th century or the first decades of the 19th century. The director of the rescue excavation has not offered any interpretation of this feature, but it seems highly likely that we could have here the only surviving example of pre-consuming deposition at a consumer site. This oyster collection merits more detailed research and the use of precise methods like the morphometric study (see e.g. [
21]), stable isotope analyses to establish sea temperature, season of harvest and provenance in Europe.
To sum up the archaeological data on oyster finds, it appears, based on the surveyed collections, that the peak of oyster consumption was during the 18th century, this culinary habit having started to develop on a larger scale in the 17th century, and, stated with some caution, the very first evidence of oysters might belong to the late medieval period, i.e., the latter half of the 15th century.