Trends in farming, trade and occurrence of native and exotic sturgeons in natural habitats in Central and Western Europe

Sturgeon catches (1981-2000, n = 338) in German, Polish and Dutch coastal waters and tributaries were analysed. The data revealed a significant decline in the endemic European sturgeon ( Acipenser sturio Linnaeus, 1758). A drastic increase in total catches of non-indigenous sturgeon species was also noted. During the study, significant changes in species catch composition were observed. These changes were correlated with the increase in intensive sturgeon aquaculture activities in Germany and neighbouring countries as well as with their increased use in the aquaria and pet trade. A link between the most frequently reared and traded species with those species dominating the catch was obvious. Major introductions were the result of accidental releases or escapements from fish farms as well as deliberate releases by anglers and aquarists. The exotic, introduced specimens thrive under natural conditions; they may therefore interfere with restoration efforts for the endemic A. sturio, and compete for habitat as well as introduce diseases and the potential for hybridization.