Use of sex steroid profiles and hematological indices to identify perinucleolus and migratory gonadal stages of captive Siberian sturgeon Acipenser baerii (Brandt, 1869) females

Summary This study describes the sex steroid profiles and hematological indices of 5‐year‐old reared female Siberian sturgeon, Acipenser baerii, at perinucleolus and migratory stages to ascertain whether they are influenced by the maturity stage. Fish of 2923 g mean weight and 89 cm mean length were reared in rectangular concrete tanks (25 × 3 × 0.6 m, mean water temperature 16.2 ± 2.2°C, fed a diet with 38.2% crude protein and 7% crude fat in 10 kg m−2). Blood samples were taken for serum steroid levels, including 17‐β estradiol (E2), testosterone (T), 17α‐hydroxy progesterone (P) and hematological indices (packed cell volume, hemoglobin, red blood cells, white blood cells, mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration as well as leukocyte differential counts). Hematological indices and the leukocyte differential count showed no significant differences among fish at the perinucleolus and migratory stages. The results indicated significant differences in E2 levels among fish at the perinucleolus and migratory stage, but the T and P levels showed no significant differences between stages. This study indicates that serum sex steroid measurements and histological observations can segregate females effectively at the perinucleolus and migratory stages; however, the hematological parameters did not discriminate females at these stages. Such observations provide basic information to achieve a method to determine with high accuracy the stage of sexual maturity, for better sturgeon aquaculture management.