Improved culture of the
Eurasian perch Perca fluviatilis - 1. Control of Reproduction and its
shift to off-season periods
Aquaflow Technical Leaflet 2002-86
European Network for the Dissemination of Aquaculture
RTD Information (Q5CA-2000-30105) and previously FAIR-3837, URL: http://www.aquaflow.org/
This is the first of 4 TLs describing different
aspects of an EU project to develop the culture of perch. Five RTD partners
and 5 SMEs had the objective of developing new techniques and transferring
them for ‘industrial’ application. More information on the whole project
at www.aquaproject.org
The research described here concerned the improvement
of photo-thermo periodic induction for shifted spawning and the
determination of egg and larval quality.
Broodstock from the same origin (initially reared in
re-circulation system) were divided into two groups: Group I 250-350g, and
Group II 350-400g and, after an acclimatisation period of one week, the
water was decreased from the initial 22°c to 6-7°c over a period of six
weeks and was maintained at that temperature for five months. The
photoperiod was kept constant at 12h light/12h dark. Group I broodstock were
found to have a better response to water-cooling, as measured by the
gonado-somatic index.
The best condition fish (71% of the initial lot) were
selected for the progressive warming phase, which was conducted over 1 or 2
months. A one-month warming period (from 6-14°c) was found to be preferential, and spawnings were obtained,
29% of which were viable, with fertilisation rates varying from 5 to 90%.
This is the first record of out-of-season spawning, although the larvae were
found to be small (4.7mm, 0.5mg). Larval viability of 266 hours was
confirmed through a starvation resistance test. This was evaluated against a
‘reference quality level’ obtained over a spawning period (April – May
2000) during the natural spawning season. The fertilisation level was high
over the entire period (70-90%) but larval resistance was much higher
(starvation resistance 160 hours, osmotic stress after 90 minutes: 50%) at
the beginning of the period than in the middle of it, when starvation
resistance was only 65 hours and the osmotic stress after 90 minutes only
4.5%. In the second part of the reproduction period, the larvae were found
to be of intermediate quality.
Although this would appear to be the first time that
broodstock fish with no previous gonadic development have been induced to
spawn out of season, the response by females and fertilisation rates are
still insufficient. However, further refining of the protocols, only based
on environmental factors, will allow more frequent juvenile supply to
on-growing farms.
For more information:
FONTAINE
Pascal
Laboratoire de Sciences AnimalesUniversité Henri Poincaré
34 Rue Ste Catherine
54000 Nancy
France
Phone : +33 3 83 30 28 41
Fax : +33 3 83 32 30 16
E-mail: Pascal.Fontaine@lsa-man.u-nancy