​​​​​​​​Oysters have been consumed for as long as man has inhabited the coast. The European oyster was once transported in abundance to the Roman Empire, where it was revered by hungry aristocrats as a status symbol and aphrodisiac. Centuries later, however, as the shellfish had become more readily available throughout Western and Southern Europe, they were being eaten by the poor and by millions in bars and brothels.

The oyster later became a sought-after commodity for the Russian elite who, over the 18th and 19th centuries, were captivated by a wider Europe whose way of life they wished to emulate. Part of this included the desire to source their own oyster supply, which prompted efforts to harvest the creature in the Gulf of Finland. Over several centuries starting in the 1700s, several farming attempts occurred, but these ventures were ultimately unsuccessful due to the sea in the area being too cold to support the mollusc's reproduction and growth. It was only with the expansion of the Russian Empire to more southern waters that oysters became more freely accessible to the home market.

Painting a historical picture

The story of the oyster and the social and economic drivers behind its consumption in Russia was told by researcher Alexei Kraikovski at the recent meeting of ICES Working Group on the History of Fish and Fisheries (WGHIST) in Italy. Kraikovski, a cultural and geographic history expert at the European University at St. Petersburg, is examining past endeavours by Russia to introduce oysters into the Gulf of Finland. His case study is significant because it shines a light on a practice which saw Russia try to follow Western European consumption patterns, helping to uncover an increasingly global human community.

This sparked curiosity amongst WGHIST's multinational fisheries scientists, historians, and marine biologists, who were driven to wonder how Kraikovski's work linked to other research. One such example is when, in the 19th century, other northern European countries removed young oysters from beds in Scotland's Firth of Forth to recover their own stocks – ones that had been decimated through a similar demand to that in the Russian case. Both instances highlight the cultural influences behind the upturn in consumption of a species that is now reduced in number or entirely missing from the continental coastal ecosystems it used to be part of.​

It's these kind of connections that are important to WGHIST and the challenge its members face in describing historical ecological changes in the marine environment, particularly in the context of evolving markets and more effective fishing technologies. In this way, the group is a pool of knowledge on marine historical ecology, with one of its goals being to demonstrate how this information can benefit current marine policy and management.

Mapping these changes is a complex task, and one that is built on the concept of historical baselines – data that describe conditions which occurred prior to a certain period of human disturbance. Evaluating baselines and the data contained within them, however, is a complex task for several reasons. Firstly, in cases where there is a lack of long-term fisheries data, researchers have to turn to non-traditional sources such as popular articles, nautical charts, photos, art, or old narratives, which run the risk of being perceived as unreliable compared to scientifically collated data. These also often have to be transformed into a format comparable with contemporary data.

"Comparing historical and more recent data sources is a major challenge for historical ecologists," explained Ruth Thurstan, who chairs WGHIST alongside Emily Klein. "One example is the translation of some 18th and 19th century nautical charts which recorded the extent of oyster beds and other habitats; these can be converted into an areal estimate that can be compared to existing beds today. Catch records have also been identified in historical sources, including fisher testimonies, government correspondence, and popular media, in some cases many years before systematic data collection began. With careful interpretation these can be reconstructed to aid our understanding of historical change."

Another issue the group needs to deal with is providing detail on the variability of past systems using the limited data available. The term 'baseline' can be misleading, suggesting a static status ecosystems rarely attain, and often failing to reflect their dynamic nature. Finally, many North Atlantic ecosystems have been heavily modified, meaning the social and economic costs of unwinding these changes can be high. In this way, historical ecology isn't necessarily a time machine to a past era, more a way of comprehending what's already taken place and how various systems evolve.

Contemporary perspective

Historical data do, however, enable the experts to better contemplate more realistic goals for ecological health and sustainable ecosystem services, and may point to possibilities they might otherwise never consider. Data also help place fish and shellfish stock health in perspective; for example, at what point should one be considered as 'recovered'? They can also aid in developing an understanding of how both ecological and human communities respond to a range of changes, which can provide insight into future change.

"Kraikovsky's oyster story is a great example of how we are working to improve understanding of historical ecological dynamics within the context of changing cultural, economic and social drivers. Without this multifaceted understanding, we risk misinterpreting the historical record. By synthesizing ecological, economic, social and cultural data, we hope our approach can contribute to a fuller understanding of past changes, and hence more effective advice for management," added Thurstan. ​

Wider applications

Amongst other outputs from the group, whose October meeting was co-hosted by the EU-COST Oceans Past Platform (OPP), have the potential to be used within the context of ICES contribution to the Marine Strategy Framework Directive (MSFD)​. Here, historical data and baselines can be used to create a benchmark against which successive values of Good Environmental Status (GES) – the directive's goal across Member State waters by 2020 – can be compared. ​​