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Subject: Gymnocephalus reproduction/fwd
From: Aldo-Pier Solari <[log in to unmask]>
Reply-To:Academic forum on fisheries ecology and related topics <[log in to unmask]>
Date:Thu, 10 Apr 1997 17:23:49 GMT
Content-Type:text/plain
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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
[log in to unmask]
....
eof

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