The Republic of Lithuania is located on the south-east coast of the Baltic Sea. It is predominantly a continental country with only 90 kilometres of the marine coastline. Only five other European countries – Montenegro, Slovenia, Belgium, Bosnia and Herzegovina and Monaco have a shorter marine coastline that the one of Lithuania. As result, Lithuania has the shortest Baltic Sea coastline of the nine countries surrounding the Baltic Sea – Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, and Sweden – and, therefore, Lithuania has the smallest area of the territorial sea, the contiguous zone and the exclusive economic zone of the Baltic Sea.

The landscapes and seascapes of the Southeast Baltic graded coast are in sharp contrast with the natural features of the other two South Baltic seaside sub-regions. The Southeast Baltic graded coast comprises the Baltic Sea coast and its hinterland in four countries: Poland, Russian Federation (Kaliningrad Region), Lithuania, and Latvia. The landscape features have resulted from the post-glacial fluctuations of the Baltic Sea level combined with the sediment input from large rivers, erosion of glacial promontories, and longshore marine sediment drift (Gelumbauskaitė 2003). These strong external forces have created a remarkable coastal landscape mosaic with wide sandy beaches, and dune ridges (Fig. 5).

The dune landscapes of the Lithuanina Baltic graded coast is interspersed with large coastal lagoon, coastal lakes and wetlands, as well as ancient and active coastal cliffs. The large barrier spits – Curonian, one of the largest river deltas in the Baltic Sea Region Nemunas, as well as one of the largest lagoons in Europe – Curonian – all can be found along this relatively short strip of the Lithuanian Baltic Sea coast along with some of the best sandy beaches in the entire Baltic Sea Region (Žaromskis, Gulbinskas, 2010).

The non-tidal Curonian Lagoon is a shallow semi-locked and nearly freshwater body, located on the southeast rim of the Baltic Sea. It is the largest Baltic Sea lagoon (surface area 1,586 km2, i.e. some 30 times larger than Lesina Lagoon). The Nemunas River (catchment basin – 98,200 km2) discharges into the lagoon on its way to the Baltic proper. The average depth of the Curonian Lagoon is 3.8 m, and the maximum depth reaches 5.8 m. Salinity varies from 6‰ at the sea entrance to just 0.1‰ at the river mouths.

Politically, the Curonian Lagoon is divided into two parts, the northern one belonging to Lithuania and the southern one to Kaliningrad Oblast, which is the exclave territory of Russian Federation. The area is in the transition zone from the temperate maritime climate to the continental one. Average annual precipitation level is approximately 750 mm. Ice usually covers the Curonian Lagoon in December, but frequent changes of weather conditions often cause ice breaking and melting (Povilanskas 2004). The Curonian barrier spit separates the Curonian Lagoon from the Baltic Sea. Dune landscapes of the spit are still the most dynamic in the Baltic Sea area (Urbis et al. 2019). The major part of the east coast of the lagoon is or has historically been part of the Nemunas Delta, which stretches about 70 km inland.

Since the commercial fish like salmon, sea trout, twaite shad or smelt prevailed in the catches, the main fishing areas traditionally had been either in the lagoon or in the mouths of the Nemunas tributaries and branches or regularly flooded shallow deltaic lakes as well.

The environment and the societies of the surveyed lagoon areas have undergone tremendous changes during the modernity from the Napoleonic reforms till nowadays. These changes had resulted in economic ups and downs within the course of modern history. There always existed specific management differences between the two lagoons, but similarities prevailed. It is evident from the scheme (Fig. 9), which shows what the resulting relative economic share of yielded local commodities from the lagoons (fish) and their fringes (agricultural products) on the regional scale in various phases of the lagoon ecosystem evolution was. We see that both lagoon areas were the most productive in relative terms in the pre-modern age and during the climax of land reclamation efforts. However, any radical changes in the tenure of land and water or ecosystem management soon inevitably led to imminent economic and ecological crises in both lagoons.

The Curonian Lagoon development in the modernity shows that the main characteristic feature of the evolution of the lagoon landscapes and ecosystems is active human interference with natural processes. Such interference had caused the depletion of fish resources, reclamation of aquatic-terrestrial ecotones, and economic shift towards reliance on the subsidized intensive agriculture in the reclaimed areas. As it is amply described in the literature, similar negative processes had adversely affected other European lagoons in the modernity as well.

Such nature management policy had resulted in declining diversity of migratory fish and bird species, and sharp production crises in the lagoon areas. This policy is unsustainable in the long time run in both economic and ecological terms. Therefore, the transformation of some lagoon fringes back into natural marshes and floodplains should be considered, with pumping being stopped, and water is allowed to stream in and out. Such management option would increase the acreage of valuable habitats for fish and waterfowl, and let the natural ecological processes to continue.