Introduction
Sturgeon species and populations have experienced a dramatic collapse mainly due to a progressive disruption of habitat suitability in their distribution range and overexploitation for commercial purposes (He et al., 2017) . This has pushed many of the species to the brink of extinction (Congiu et al., 2023) . Consequently, massive efforts have been implemented in the past and others will be needed in the future, to rescue these threatened species.
In this context, ex situ conservation is a cornerstone of protection, maintenance and propagation of species outside their natural habitats and should guarantee needed conditions for secure life and optimal breeding so that releases can be put in place in the future (Overton et al., 2023) . For sturgeons, ex situ conservation is entrusted, in a relevant part, to aquaculture facilities where they are farmed mainly for commercial interest, opening a heated debate about the use of aquaculture stocks for conservation purposes and about which features they should have to ensure their management success from establishment to propagation (Froehlich et al., 2017) .
Results and Discussion
High long-term performances are achieved if the ex situ strategy aims at maintaining genetic diversity of the stocks in order to minimize adaptation to captivity and genetic erosion and maximise adaptive potential after release. This is complicated in sturgeons by their complex genomes, long life cycles , late sexual maturity and large size as well as by the ease interspecific hybridisation with production of fertile progeny.
Models , principles and ex situ strategies for an informed biodiversity conservation of aquaculture stocks are presented and discussed on the bases of case studies on different sturgeon species (Barca et al., 2022; Boscari et al. 2121; 2022). Important conservation topics that will be covered are: the role of the identification of conservation units or geographic structured populations , the importance of stocks’ pureness , the principles underlying the selection of target stocks for conservation such as the assessment of relatedness and the reconstruction of pedigree information, and useful strategies to set-up specie-specific breeding plan.
Conclusion
The aim of this presentation is to stimulate the discussion on the importance of a shared approach among different stakeholders. Recognition of this need will require adoption of a new parad igm for sturgeon ex situ conservation, in which on the one hand aquaculture makes an additional effort to preserve diversity while on the other hand conservation projects and competent authorities support the extra costs of farming-for-release. The protection o f the most endangered group of animal species would certainly benefit from this change of perspective .
References
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