Effect of maintenance at elevated temperatures on ovulation and luteinizing hormone releasing hormone analogue responsiveness of female Atlantic salmon (Salmo salar) in Tasmania

摘要: Abstract To examine the effect of maintenance at elevated water temperatures on responsiveness female Atlantic salmon ( Salmo salar ) to luteinizing hormone releasing analogues (LHRHa), sexually maturing 2-year-old were maintained 6, 11 or 16 °C from late in vitellogenesis (early April Tasmania) throughout periovulatory period (late early June). In May, fish treated with LHRHa (25 μg kg −1 body weight) by injection a cholesterol pellet. Controls received saline injections and blank pellets. Fish anaesthetised blood sampled treatment, 48-h intervals for up 8 days post injection. Thereafter, regular ovulation checks conducted until end experiment. Plasma levels gonadal steroids testosterone (T), 17β-estradiol (E 2 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) measured egg fertility survival eyed stage assessed. controls, delayed relative held 6 whereas, °C, was inhibited holding temperature reduced day 35 Treatment advanced both but had no °C. Elevated plasma 17,20βP controls only evident those (>100 ng ml ), whereas treatment associated high (>60 ). contrast, there little production irrespective prior significant reductions ova (84.0% 17.3%, respectively) (97.9% 75.6%, (95.3% 44.4%, respectively). The LHRHa-treated did not differ significantly that either produced nonviable died ovulation. These observations indicate endocrine dysfunction confirm lack maturational competence temperatures, suggest impaired pituitary limited 20β-HSD activity may contribute observed