Effect of elevated summer temperatures on gonadal steroid production, vitellogenesis and egg quality in female Atlantic salmon

Authors

  • H. R. King,

    Corresponding author
    1. Salmon Enterprises of Tasmania Pty. Ltd., P. O. Box 1, Wayatinah, Tasmania 7140, Australia and
    2. School of Aquaculture, Tasmanian Aquaculture & Fisheries Institute, University of Tasmania, Locked bag 1-370, Launceston, Tasmania 7250, Australia
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  • N. W. Pankhurst,

    1. School of Aquaculture, Tasmanian Aquaculture & Fisheries Institute, University of Tasmania, Locked bag 1-370, Launceston, Tasmania 7250, Australia
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  • M. Watts,

    1. School of Aquaculture, Tasmanian Aquaculture & Fisheries Institute, University of Tasmania, Locked bag 1-370, Launceston, Tasmania 7250, Australia
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  • P. M. Pankhurst

    1. School of Aquaculture, Tasmanian Aquaculture & Fisheries Institute, University of Tasmania, Locked bag 1-370, Launceston, Tasmania 7250, Australia
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‡Tel.: +61 3 6289 3280; fax: +61 3 6289 3290; email: harry_king@saltas.com.au

Abstract

Groups of Tasmanian female Atlantic salmon Salmo salar L. were maintained at 14, 18 and 22° C for 3 months from mid-summer (January). Blood plasma levels of 17β-oestradiol (E2), testosterone (T), cortisol and vitellogenin (Vtg) were measured at regular intervals, and in autumn (April) temperatures were reduced to 8° C to facilitate spawning and egg incubation. Maintenance at 22° C during vitellogenesis was associated with a general reduction in plasma E2 levels and an early reduction in plasma Vtg levels relative to those observed in fish held at 14 and 18° C. Significantly reduced oocyte diameters in ova from fish held at 22° C (5·4 mm cf. 5·7 mm) confirmed reduced maternal investment, and an increase in the incidence of previously undescribed chorion damage suggested that zonagenesis may also have been impaired. As a result, the fertility and survival of ova from fish exposed to 22° C (69 and 42%, respectively) were significantly reduced relative to those of ova from fish maintained at 14° C (93 and 86%) and 18° C (86 and 84%).

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