Abstract
One of the last wild populations of the critically endangered stellate sturgeon (Acipenser stellatus) survives in the Danube River. Limited knowledge about the genetic structure, ecology, and evolution of this species led to poor and inconsistent management decisions with an increased risk for species extinction in the wild. Here we show the results of genetic structure screening of the Danube River wild population over 12 years timespan. Our research does not bring evidence of population recovery. No genetic structuring was identified at the mitochondrial level concerning spawning migration timing, sampling locations, and developmental stages. Eleven maternal lineages were revealed based on restriction fragment lengths analysis of the D-loop region, with one haplotype as the most frequent. While this could be the result of a massive restocking activity using a reduced number of spawners, our data does not support it. The selection of mitochondrial haplotypes under the pressure of habitat contraction and the narrower range of temperature variation since dams’ construction on the river could explain the observed distribution. Several factors of managerial concern are discussed. Our results provide baseline data on the mtDNA diversity in a critically endangered species of exceptionally high socioeconomic and conservation interest.
Highlights
In the Black Sea basin still survives the last wild population of stellate sturgeon (Acipenser stellatus, Pallas 1771) able to undertake upstream spawning migration into the Danube River [1].Along with other sturgeon species that spawn in Danube River, during the 20th century, the stellate sturgeon was subject to heavy fishing pressure, leading to a reduction of the population size to critical levels [2]
Identification of the genetic structure of a population subject to multiple stressors is a preliminary condition for proper management of its conservation and sustainable use. It is the case of the remaining stellate sturgeon population, an endangered species still naturally spawning in the lower Danube River
While a certain heterogeneity level was evident in our study, no genetic structuring was identified at the mitochondrial level concerning spawning migration timing, sampling locations, and developmental stages
Summary
In the Black Sea basin still survives the last wild population of stellate sturgeon (Acipenser stellatus, Pallas 1771) able to undertake upstream spawning migration into the Danube River [1].Along with other sturgeon species that spawn in Danube River, during the 20th century, the stellate sturgeon was subject to heavy fishing pressure, leading to a reduction of the population size to critical levels [2]. In the Black Sea basin still survives the last wild population of stellate sturgeon (Acipenser stellatus, Pallas 1771) able to undertake upstream spawning migration into the Danube River [1]. Changes in the population structure, water pollution, and illegal fishing contributed to the significant decline of the species stocks. Under these circumstances, the stellate sturgeon in the Black Sea Basin was listed as endangered species in Appendix II of CITES on 1st of April 1998 [4] and as critically endangered in the Red List of IUCN [1]. A limited number of studies on genetic diversity, population genetic structure, and demographic history of A. stellatus have been carried out [8,9,10,11,12,13], with only a few of them investigating the stellate sturgeon in the Black Sea and Danube River [14,15,16,17,18]
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