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FYI. Received at FE-request. Cheers, APS.
Date: Thu, 10 Apr 1997 17:46:34 +0000
From: [log in to unmask] (Henri Persat)
Subject: Gymnocephalus reproduction
Dear Colleague,
Recently someone asked about reproduction of ruffe Gymnocephalus
cernuus. Having deleted his message, I cannot send it to that
person directly. So, would you mind to be kind enough to forward
the following information to the right Email.
BASTL I., 1988: On the reproduction and biology of three
Gymnocephalus species (Pisces: Percidae). Prace Ust. Rybar.
Hydrobiol., 6:9-31. Summary: Gymnocephalus cernuus, G. baloni
and G. schraetser belong to polycyclic species with asynchronus
gametogenesis and partial spawning. Males of G. cernuus attain
sexual maturity at standard length (Sl) 32-80 mm, of G. baloni at
51-90 mm, and of G. schraetser at 70-90 mm; females of G. cernuus
at 57-90 mm, of G. baloni at standard length over 78 mm, and of
G. schraetser at 78-120 mm. The spawning period of G. cernuus
last from mid-April to mid-June at water temperatures 7.1-20.2
=B0C, that of G. baloni from the end of the second decade of
April to the mid-June (8.2-20.2=B0C), and that of G. schraetser
from the end of the second decade of April to the end of May
(8.2-20.2=B0C). The values of absolute and relative fecundity
are given in Tab.5. The absolute individual fecundity of the
species under study is statistically highly significantly
positively correlated with standard length, total weight and
weight of eviscerated females. The regression equations of these
relations and the values of correlations coefficienbts are given
in Tab.6.
Some notes : Average fecundity 23000 eggs for female of about
100mm, highest fecundity observed 61000 eggs. Three egg groups
at the beggining of spawning. First group 8400 eggs. Sometimes
four egg groups. Number of batches probably higher than the
number of groups, one group being layed in several batches (and
occasions ?).
I hope that will be useful.
Yours sincerely,
Henri PERSAT =46reshwater and Large River Ecology Laboratory ESA
CNRS 5023 - Universite Lyon 1 43, Bvd du 11 Novembre 1918 69622
VILLEURBANNE Cedex, France
Tel (33) 04 72 44 84 35 =46ax (33) 04 72 43 11 41 E.mail
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