Sexual maturity in sea trout, Salmo trutta L., running up the River Calonne (Normandy, France) at the 'finnock' stage |
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Authors: | G Maisse B Mourot B Breton A Fostier O Marcuzzi P Y Le Bail J L Baglinière A Richard |
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Institution: | I.N.R.A., Station de Physiologie et d'Ecologie des Poissons, 35042 Rennes Cedex;Conseil Supérieur de la Pêche, Délégation Régionale No. 2.84 rue de Rennes. 35510 Cesson Sévigné, France |
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Abstract: | Sexual maturation in sea trout ( Salmo trutto L.) running up the River Calonne (Normandy, France), at the finnock stage, is characterized. Autopsy of 118 finnock in summer showed that 87 ± 7% aged 2+ and 33 ± 15% aged 1 + were undergoing gametogenesis. In autumn all the fish were maturing. The analysis of plasma levels of 11-ketotestosterone, 17β-oestradiol, maturational gonadotropin and vitellogenin showed that only females in vitellogenesis can be well identified in summer (plasma vitellogenin greater than 0.30 mg ml-1). The morphological recognition of females among 134 autumn finnock and the ELISA assay of plasma vitellogenin of 814 summer finnock, demonstrated that vitellogenic females represented 12 ± 2%0 of the 1 + individuals and 46 ± 2% of 2+ fish captured during the 1985 run. The question of a possible relationship between the salinity tolerance ofjuvenile trout migrating towards the sea in the spring and their age on first migration in the river is discussed. |
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Keywords: | Salmo trutta finnock maturity vitellogenin ELISA |
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