The influence of sex steroids in commercial fish meals and fish diets on plasma concentration of estrogens and vitellogenin in cultured Siberian sturgeon Acipenser baeri

Sex steroid levels were dctermined in various commercial fish meals and complcte dicts. The results obtained demonstrate that estrone (E,), 17P-estradiol (El) and androgens (A) (testosterone and 11ketotestosterone), are present in diets in high quantities (up to 935f 350ng/100g for E,, 615f 190ng/100g for El and 1 100&120ng/100g for A) and with considerable variation both between diffcrent dicts, and between differcnt batches of the same diet. These high levels of sex steroids are thought to influence the sex steroid plasmatic Icvels and plasma vitellogenin content in fish. Plasma sex steroid assays in the Siberian sturgeon Acipenser barri show that plasmatic 17 0-estradiol lcvels are ncvcr significantly different betwccn males and femalcs at various stages of oogenesis and spermatogencsis, exccpt in 6 year old fcmalcs in stage IV, which corresponds to the maximum incorporation of vitellogenin. In males the plasma 17P-cstradiol levels are exceptionally high and induce vitellogenin synthesis, as dcmonstrated by various chemical and immunological techniques.