Sterlet Sterlet The sterlet ("Acipenser ruthenus") is a relatively small species of sturgeon from Eurasia native to large rivers that flow into the Black Sea, Azov Sea, and Caspian Sea, as well as rivers in Siberia as far east as Yenisei. Populations migrating between fresh and salt water (anadromous) have been extirpated. Due to overfishing (for its flesh, caviar, and isinglass), pollution, and dams, the sterlet has declined throughout its native range and is considered vulnerable by the IUCN. Restocking projects are ongoing, and it has been introduced to some regions outside its native range, but the latter have generally not
National Register of Historic Places property types National Register of Historic Places property types The U.S. National Register of Historic Places (NRHP) classifies its listings by various types of properties. Listed properties generally fall into one of five categories, though there are special considerations for other types of properties which do not fit into these five broad categories or fit into more specialized subcategories. The five general categories for NRHP properties are: building, district, object, site, and structure. Listed properties generally fall into one of five categories, though there are special considerations for other types of properties which do not fit into these five broad categories or