Distribution and genetic diversity of sturgeons feeding in the marine area of the Danube Delta Biosphere Reserve

Abstract

The NW Black Sea basin supports sympatric population of beluga (Huso huso), stellate sturgeon (Acipenser stellatus) and Russian sturgeon (A. gueldenstadetii). These ecologically similar fish exhibit varying life strategies during their extended juvenile period andappear to overlap at some stages within the marine coastal waters. The aim of the study was to assess the distribution and genetic diversityof sturgeons feeding in the Black Sea coastal area of the Danube Delta Biosphere Reserve (DDBR) during 2012. A total number of 76sturgeons (70 stellate , 5 beluga and 1 Russian sturgeon) were captured during three fishing expeditions along the Romanian Black Sea coast of the DDBR using two fishing methods: active (pelagic trawling) and passive fishing (bottom set trammel nets). A high number of stellate sturgeonswere captured in Sahalin and Zatoane areas highlighting their importance as feeding sites for all life stages of this species. Capturing of only 5beluga sturgeon specimens suggested that coastal waters are less important feeding areas for this species. Genetic diversity of stellate and beluga sturgeons was assessed by PCR-RFLP of mtDNA D-loopregion. Six out of ten composite haplotypes were detected in stellate sturgeons and twocomposite haplotypes in beluga sturgeons. Further studies on the dynamics of sturgeon population, on behavioural and ecological factors influencing the seasonal distribution are prerequisite for improved management and sustainable use of these resources of the Black Sea.

Keywords

• wild sturgeons
• genetic diversity
• essential habitats
• sturgeon feeding
• Black Sea