Reproductive Cycle and Plasma Sex Steroid Profiles in Male Eurasian Perch Perca Fluviatilis

Abstract

From April 1995 to April 1996, the annual reproductive cycle of male Eurasian perch Perca fluviatilis was studied at the Lindre Center (Moselle, France). At monthly intervals, five males (mean body weight of 133 ± 43 g and total length of 175 ± 9 mm) were caught. From sampled organs, the gonadosomatic (GSI), hepatosomatic (HSI) and viscerosomatic indexes (VSI) were calculated and plasma testosterone (T) and 11-ketotestosterone (11KT) levels were measured. After the spawning period in mid-April, GSI and HSI dropped and VSI increased to 3.8 ± 0.1 %. In September, GSI reached its maximum (8.5 ± 1.8 %). At this time, spermatocytes, spermatids and spermatozoa were abundant, whereas in June only spermatogonia were observed. During winter, GSI was stable at approximately 5 %, HSI reached its maximum (1.9 ± 0.3 %) and VSI was low (2.6 ± 0.2 %). From April to November 1995, plasma T and 11KT concentrations were low (< 0.5 ng·mL–1). Plasma T levels increased significantly in December and reached peak levels (12.3 ± 2.1 ng·mL–1) in January, then decreased in February and increased again until spawning in April (6.8 ± 2.1 ng·mL–1). This second elevation could be related to the beginning of a new spermatogenic cycle. Plasma levels of 11KT increased significantly from October to February 1996 (4.9 ± 1.1 ng·mL–1). From February to the spawning period (April 1996), plasma 11KT decreased significantly, but values were significantly higher than those measured in fall. Males were spermiating from January to spawning in April. © 2000 Ifremer/Cnrs/Inra/Ird/Cemagref/Editions scientifiques et medicales Elsevier SAS Reproductive cycle / sex hormones / steroids / male / Perca fluviatilis Resume — Cycle de reproduction et teneurs en steroides du plasma chez la perche eurasienne mâle Perca fluviatilis. Le cycle annuel de reproduction de la perche eurasienne mâle, Perca fluviatilis, est etudie au Domaine de Lindre (Moselle, France) d’avril 1995 a avril 1996. Cinq mâles (poids moyen de 133 ± 43 g, longueur totale moyenne de 175 ± 9 mm) sont examines mensuellement. Les indices gonadosomatique (IGS), hepatosomatique (IHS) et viscerosomatique (IVS) sont calcules, les teneurs en testosterone (T) et 11-ketotestosterone (11KT) mesurees. Apres la periode de ponte (mi-avril 1995), IGS et IHS diminuent et l’IVS augmente (3,8 ± 0,1 %). En septembre, l’IGS atteint son maximum (8,5 ± 1,8 %) et les testicules presentent des spermatocytes, des spermatides et des spermatozoides, alors qu’au mois de juin, il n’y a que des spermatogonies. Pendant l’hiver, l’IGS reste stable (environ 5 %), l’IHS atteint son maximum (1,9 ± 0,3 %) et l’IVS reste faible (2,6 ± 0,2 %). D’avril a novembre 1995, les teneurs en testosterone et 11KT du plasma sont faibles (< 0,5 ng·mL–1). La teneur en T du plasma augmente fortement en decembre pour atteindre un maximum en janvier (12,3 ± 2,1 ng·mL–1). Elle diminue en fevrier, puis s’eleve a nouveau jusqu’a la ponte en avril (6,8 ± 2,4 ng·mL–1). Cette seconde elevation pourrait coincider avec le demarrage d’un nouveau cycle de spermatogenese. La teneur en 11KT augmente significativement d’octobre a fevrier 1996 (4,9 ± 1,1 ng·mL–1), puis elle diminue de fevrier jusqu’a la ponte en avril 1996, mais reste superieure a celles dosees a l’automne. De janvier jusqu’a la periode de ponte, les mâles sont spermiants. © 2000 Ifremer/Cnrs/Inra/Ird/Cemagref/Editions scientifiques et medicales Elsevier SAS Cycle de reproduction / hormones sexuelles / steroides / mâle / Perca fluviatilis * Corresponding author: [e-mail] Aquat. Living Resour. 13 (2) (2000) 99−106 © 2000 Ifremer/Cnrs/Inra/Ird/Cemagref/Editions scientifiques et medicales Elsevier SAS. All rights reserved S0990744000001467/FLA