A sturgeon view on conservation genetics

The order of Acipenseriformes (sturgeon and paddlefishes) contains the economic most valuable species in world trade: the producers of black caviar. Mainly because of their high economic value, sturgeon and paddlefishes were and are the goal of many conservation programs worldwide. In this review, I present some of the main conclusions that can be drawn from previous conservation efforts. My review is divided into two parts. The first part deals with species identification methods, which are necessary for international trade control (Convention on International Trade in Endangered Species of Wild Fauna and Flora). Considering the outcome of all previous forensic studies, I conclude, firstly, it is necessary to use large sample sizes to avoid misinterpretation of possible diagnostic substitutions, and, secondly, the combination of both DNA types (mitochondrial and nuclear markers) is recommended for correct species identification. The second part deals with the influence of restocking/release programs on native populations. The outcome of previous stocking efforts indicates that, in most cases, stocking with nonnative specimens is economically nonsense because most translocation efforts failed. In addition, in cases where such efforts were successful, they influenced negatively the genotypic structure (inbreeding and outbreeding depressions) of native populations. In fact, nonnative stocking does jeopardize adaptation and blurs the genetic differences used to discriminate populations. Furthermore, if it is necessary to release individuals to avoid extinction, released specimens should be as young as possible (homing fidelity).