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Effects of GnRHa and pimozide treatments on the timing of ovulation and on egg quality in Arctic charr (Salvelinus alpinus) at 5 and 10 °C

Published online by Cambridge University Press:  15 July 1996

Christian Gillet
Affiliation:
Station d'Hydrobiologie Lacustre, INRA, BP 511, F-74203 Thonon Cedex, France
Bernard Breton
Affiliation:
Laboratoire de Physiologie des Poissons, INRA, Campus de Beaulieu, F-35042 Rennes Cedex, France
Tomasz Mikolajczyk
Affiliation:
Academy of Agriculture, Department of Ichthyobiology, 30144 krakow-Myldniki, Poland
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Abstract

The effectiveness of different gonadotropin releasing hormone analogues (GnRHa) and/or pimozide for inducing ovulation in Arctic charr was investigated at two different temperatures: 5 °C, a temperature suitable for spontaneous ovulation in Arctic charr and 10 °C, a temperature which inhibited ovulation in Arctic charr. At 5 °C all the different GnRH analogues tested were able to induce and synchronize ovulation. At 10 °C a sustained release preparation of D-tryptophan6 luteinizing hormone releasing hormone (D-Trp6LH-RH) at 20 μg.kg−1 and an acute release preparation of D-arginine6salmon GnRH (D-Arg6 sGnRH) at 100 μg.kg−1 were able to induce ovulation in 80% of the females within 15 days (versus 2% in controls). Pimozide alone or in combination with a low dose of D-Arg6sGnRH was able to induce some ovulation at 10 °C, suggesting that a dopamine inhibition of gonadotropin secretion could occur at 10 °C. Egg survival in groups receiving GnRHa at 5 °C was comparable to controls (73%) except in the group receiving GnRHa in combination with pimozide (45%). At 10 °C, egg survival was significantly lower than controls at 5 °C, except for the group receiving pimozide alone. At both temperatures, egg survivals of each spawn were negatively correlated with the plasma gonadotropin (GtH2) level of the reproducing females except in groups receiving a sustained release preparation of D-Trp6LH-RH.

Type
Research Article
Copyright
© IFREMER-Gauthier-Villars, 1996

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