The presence of Acipenser sturgeons in the Iberian Peninsula: a review of the existing literature

The conservation status of sturgeon species is highly alarming. Six of the European Acipenser species are critically endangered. Several studies developed in the last decades have analysed the distribution of sturgeons in the Iberian Peninsula, questioning the possibility of the native character of some Acipenser species there, with a special focus on the Adriatic sturgeon, A. naccarii. We review the available knowledge on the distribution on Iberian Acipenser sturgeons, in order to ascertain their nativeness status, as a necessary tool to implement measures for their management and conservation. One vagrant specimen of A. oxyrinchus, and several released or escaped specimens of A. baerii and A. naccarii have been recorded in the Iberian Peninsula. Our results show that the Atlantic sturgeon A. sturio is the only native sturgeon species that has had breeding populations in the past in the Iberian Peninsula. Regarding A. naccarii, further evidence is required to prove its dubious native character in the Iberian Peninsula. Although the reviewed studies have solidly shown that A. naccarii has been present outside the Adriatic basin, the presence of isolated individuals does not constitute sufficient evidence to sustain the existence of past breeding populations.