Preservation of newly-extracted roe sacks of sturgeons for subsequent harvesting of roe and caviar production, wherein said preservation employs an oil derived from roe sack membrane normally discarded in conventional caviar production. Such preservation enables roe sacks with retained roe derived from farmed or wild sturgeon to be stored and transported whereby export can be considered. The same oil, or fatty acid-containing fractions thereof, may also find use in dietary compositions, e.g. pet foods.