Caviar composition in wild and cultured sturgeons -: impact of food sources on fatty acid composition and contaminant load

Caviar production from aquaculture is increasing whereas fishery yields are in decline. It is therefore of interest to identify the differences in caviar of various origins. In particular, the question arises whether the composition of caviar is attributable to feeding and processing practices. Egg size, protein and fat content are not applicable for species discrimination. Gross composition of the end-product largely depends on the salt content and thereby is influenced by the processing technology. According to our results, the composition of sturgeon caviar from intensive aquaculture varies to a large extent from that of wild origin. Fatty acid composition in extensively reared sturgeon did not differ largely from that of wild-caught fish. As the difference is only apparent between fish reared on formulated diets and wild-caught fish, the applicability of this tool for product source determination is restricted. Cadmium and lead are not enriched in the eggs. The elevated levels detected for copper and zinc reflect the requirements of the fish. The amount of chlorinated hydrocarbons (SigmaDDT, SigmaPCB, SigmaHCH) varied over a wide range, revealing typical differences related to origin, source and species. Based on the observed differences between caviar from wild and intensively farmed fish, development of a diet is necessary to coincide with the requirement of sturgeons. The study suggests altering the fatty acid composition by reducing the linoleic ( 18 : 2) acid content while increasing the arachidonic ( 20 : 4) acid to match the caviar composition in wild-caught sturgeons. This also is expected to improve growth and reproduction in sturgeons raised in captivity.