Conservation

Despite ongoing mitigation efforts the risk to loose most of the remaining populations of sturgeons and bringing several species close to extinction is extremely high.

The options to mitigate the negative effects of most of the activities and methodologies must consider to rehabilitate/enhance the functional quality of critical sturgeon habitats.

Releasing captive-bred fish is a common practice in many countries to manage aquatic resources that are heavily exploited (e.g. for commercial or sport value, and threatened species). There are many problems with such releases, in particular with regard to genetics. Among them are the potential for „introgression“ (when genetic characteristics of the captive population differs from those of the wild ones), the potential loss of adapted genes or gene complexes as well as the homogenization of a previously distinct genetic mix of populations through swamping a region with a common gene pool.

The question also is to what extent a gene flow from hatchery-reared individuals can natural populations sustain before compromising genetic integrity, particularly when the natural populations are declining to near extinction level. The above recommendations reflect these concerns and should be considered as conditional measures to minimize risk of inbreeding (exposure to the effects of deleterious recessive genes through matings between close relatives) or outbreeding depressions (hybrid vigor or heterosis).

It is imperative to maintain genetic diversity to the extent possible for any of the managed sturgeon populations in order to allow for adequate adaptation capacity of wild (or re-established) populations to changing environmental conditions (including climate change, disease resistance, trophic alterations).