sevruga
noun
sev·ru·ga sə-ˈvrü-gə 
se-
: a gray caviar from a sturgeon (Acipenser sevru) of the Caspian Sea with roe that is smaller than that of osetra
also : the fish
Example Sentences
Recent Examples on the Web Opocensky bakes and salts them in hay, then garnishes them with Japanese cream accented with Sicilian lemons and chive oil and tops it all with perch and sevruga caviar. 
Eric Rosen, WSJ, 10 Dec. 2018
Eric Rosen, WSJ, 10 Dec. 2018 Word History
Etymology
Russian sevryuga, a species of sturgeon
First Known Use
1591, in the meaning defined above