Transfer of royal fish and the non-evolutionary history of Black Sea sturgeons

The evolutionary relationship between Caspian and Black Sea sturgeons has long attracted scholarly attention. Although the two basins have been hydrologically isolated for at least 5000 years, genetic studies reveal the presence of Black Sea sturgeon haplotypes identical to those of the Caspian Sea alongside other, more diverse and numerous haplotypes unique to the Black Sea population. At the same time, the overall genetic diversity of Black Sea sturgeons remains significantly lower than that of their Caspian counterparts. For decades, researchers have sought to explain these findings through exceptional evolutionary mechanisms, often assuming processes specific to sturgeons alone. This study proposes an alternative—a political and historical explanation for what appears to be an ecological anomaly. Following two successive ecological catastrophes that struck the Black Sea during the early Middle Ages, regional conditions for artisanal production and fisheries seem to have declined sharply. Drawing on relevant medieval Georgian sources, the author suggests that in the first half of the twelfth century, sturgeons from the Caspian basin were intentionally introduced into the Black Sea via eastern Georgia as part of a royal enterprise. This hypothesis offers a coherent historical framework that accounts for the observed ecological and genetic discontinuities within Black Sea sturgeon populations.