Effects of dietary estradiol-17β in juvenile shortnose sturgeon, Acipenser brevirostrum, Lesueur

• Published in: Aquaculture Vol. 270; no. 1; pp. 405 - 412
• Main Authors: Flynn, Shawn R., Benfey, Tillmann J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 28.09.2007; Elsevier Science
• Subjects: Acipenser; Acipenser brevirostrum; Animal aquaculture; Animal productions; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; copper; Copper toxicity; Ecotoxicology, biological effects of pollution; estradiol; estrogens; feed supplements; Feminization; fish culture; Fundamental and applied biological sciences. Psychology; General aspects; Gonadal development; histology; kidneys; liver; mariculture; marine fish; ovaries; Salmonidae; Sex reversal; Sturgeon; water pollution; Feminization; Sturgeon; Copper toxicity; Sex reversal; Gonadal development; Toxicity; Estradiol; Young animal; Vertebrata; Diet; Gonad; Pisces; Development; Copper; Aquaculture
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2007.04.073

Shortnose sturgeon, Acipenser brevirostrum, were fed estradiol-17β (E 2) in commercial salmon feed in two separate experiments, with the aim of creating all-female populations for aquaculture. In the first experiment, 5-month-old fish were fed 0 (control), 10, 50 and 100 mg E 2/kg feed during a 9-month trial starting in September. This experiment was confounded by copper contamination of the heated water source that appeared to cause E 2-dose-dependent mortality. As a result, a second, parallel experiment was conducted on the same year class of fish starting at age 7 months in November, but with hormone dosage reduced to 0, 10, 25 and 50 mg E 2/kg feed in a 7-month trial. In both experiments, control and 10 mg E 2/kg groups remained active and fed well, but the other fish were less active and fed less as E 2 dosage increased. Histological observations indicated that anatomical differentiation of the ovaries had begun in 3 of 5 individuals examined at the start of Experiment 2. In January, sub-samples of 6 fish from each group showed that E 2-treated fish had mottled livers, swollen kidneys and reduced gonad size. The number of hepatocytes and their staining characteristics were similar in both the control and 10 mg E 2/kg groups. At 25 mg E 2/kg and higher, the number of hepatocytes and the presence and quantity of yolk protein increased with the E 2 dosage. At final sampling in May, all of the treatment groups showed some individuals with these pathologies evident macroscopically, and their frequency and severity increased with E 2 dosage such that all individuals of the 100 mg E 2/kg group were affected. In general, fish grew better and had lower mortality in Experiment 2 (8.5%, as compared to 15.2% for Experiment 1) during the period of E 2 treatment. Final sampling revealed that all treated fish were apparently feminized in both experiments, based on anatomical differentiation of the gonads. Control groups, on the other hand, were 65 and 58% female in Experiments 1 and 2, respectively.