Abstract Although the Cretaceous is widely regarded as a time of great evolutionary transition for freshwater fish fauna North America, fossil record this period notoriously poor, consisting mostly fragments and isolated skeletal elements. Exceptions include acipenseriforms, discussed in paper, some exceedingly rare teleosts. Here we describe two new species well-preserved sturgeons (Acipenseri...

beluga sturgeon ( huso huso linnaeus, 1758) fingerlings are released into the caspian sea for recruiting and enhancing commercial and recreational fishing purposes. these fingerlings are reared in fresh water, but released to the estuaries that may be caused mortalities due to acute osmotic stress. in this study, the fingerlings in whole ( in vivo ) or their gill tissue ( in vitro ) were expose...

Evolution of the nucleoli has been followed during oogenesis in the Acipenserid fishes, Acipenser ruthenus (the sterlet) and A. guidenstadti (the sturgeon) using light and electron microscopes. In the ovaries of adults, the oogonial nuclei usually have a single nucleolus with an adjacent mass of paranucleolar fibrillar material. The cytoplasm of the oogonia contains two dense bodies peculiar on...

Sturgeons (family Acipenseridae) are valuable commercial fish and aquaculture resources. The Acipenser genus includes about 20 species, 12 of which recorded for the Russian territory. One rarest is Sakhalin sturgeon A. mikadoi Hilgendorf, 1892. At present, its population size significantly decreased species close to extinction. Natural populations have survived in Tumnin River Khabarovsk Region...