Past and present status of sturgeons in Hungary and problems involving their conservation

Sturgeons had played an important role in the history of Hungarian fisheries, but over-fishing, followed by extensive river regulations and deterioration of habitat quality have caused a decrease in populations to the verge of extinction in the middle Danube and its tributaries. Stellate sturgeon (Acipenser stellatus) and great sturgeon (Huso huso) are practically vanished from the Hungarian waters and Russian sturgeon (A. gueldenstaedti) and ship sturgeon (A. nudiventris) have sporadic occurrence only, while Atlantic sturgeon (A. sturio) was never resident of this stretch of the Danube River. Sterlet (A. ruthenus) is the only common species caught for commercial and recreational purposes. The paper describes the past and recent status of the Middle Danubian sturgeon populations and emphasizes problems of restricted availability or lack of essential spawning and nursery habitats. Impacts of floods on sterlet population dynamics are demonstrated by long-term data of commercial fishery. Existing conservation measures, restocking and fishing regulations in Hungary are evaluated.