Conservation can serve two objectives:
to protect/conserve a current state with respect to ongoing changes or to return to conditions as they were in the past (a restoration).
In the case of nature and of aquatic environments in particular, conservation may comprise both these elements, but it should be associated with a rational approach that allows for the application of effective measures. Some of the changes underway, such as global climate related alterations, are the results of long-term changes and, as such, cannot be reverted immediately given their political, economic, and social impact. The same is true for many other anthropogenic activities that modify habitats, such as the construction of hydroelectric power plants to satisfy energy needs and the alteration of river hydrology for navigation and flood protection. To these impacts, poaching and over-fishing must also be ascribed. These are of particular relevance in the case of sturgeons due to the value of their caviar. As such, man has the obligation to mediate the effects of their activities and diminish or compensate for their consequences.
In the case of sturgeons, as with other fish species, their conservation does not intend to stop progress or oppose the legitimate interests of the inhabitants of the regions in which the species thrive, but requires a compromise to adapt the needs of development to the needs of the long-term welfare of these species and their community structures. In cases where this intervention is occurring too late, the loss of species is a detrimental result. In these cases, we are obliged to think about their reintroduction, after ensuring that the conditions of the habitats are suitable and by adopting all the measures that have been described and standardised based upon previous experiences. This framework is now available and validated in documents such as the European Action Plan for Sturgeons, adopted by the Bern Convention, and endorsed for implementation under the EU Habitats Directive on international Biodiversity Day. This work, produced by the WSCS and WWF, represents the first official action plan under this Directive for a fish species. It covers 8 sturgeon species, 7 of which are listed as critically endangered by the IUCN, and aims to conserve the last functional populations, restore habitats, stop poaching, and reintroduce sturgeon to many rivers. Another key document is the Vienna Declaration, which lists the key recommendations regarding the effectiveness of conservation management when planning or implementing activities to protect and preserve sturgeons. The Danube watershed and the Black Sea, with five native sturgeon species urgently in need of conservation measures, are model areas; offering a harmonised infrastructure which provides the opportunity for the implementation of the guiding documents to not only save the treasures of the Danube, but also to increase the wealth of nature and help protect biodiversity in the region as a whole. As such, the Danube could become a laboratory for a much needed global approach.