Improved culture of the Eurasian perch Perca fluviatilis - 2. Improvement of larval production in recirculating systems.

Aquaflow Technical Leaflet 2002-87

European Network for the Dissemination of Aquaculture RTD Information (Q5CA-2000-30105) and previously FAIR-3837, URL: http://www.aquaflow.org/

This is the second 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.

Initially, larval production in small ponds (100-200m2 in size and relying only on the natural productivity of the ponds as a feed source) was quantified in terms of survival, growth and estimated production cost, to use as a baseline for comparison. At an initial stocking density of 100 larvae (of 0,75mg) per m2, survival rates varied between 21 and 65% and harvested weight after 6 weeks averaged 0,2-0,5g. Production cost (taking into account equipment depreciation over 15 years) was estimated at between 0,02 and 0,05 € (euro) per fish.

Rearing was then conducted at different densities in indoor recirculating systems, using a feeding regime of Artemia nauplii and subsequent weaning (from day 22 to day 31) on to a commercial starter feed. Survival rates after 7 weeks of rearing (initial stocking size averaged 1,2 mg at densities of 20, 50 and 100 larvae per litre) averaged around 50% and was independent of initial stocking density. Final average weight at the end of the trial was 0,5-0,8g and the food conversion ratio varied between 1,0 and 1,3.  Although production cost (without depreciation) was estimated as 0,10 € (euro) per fish, the gains in production, especially in terms of the homogeneity of the population, was considered to outweigh this cost ‘disadvantage’, when compared to small pond culture.

The final phase of this study area was related to better controlling the sanitary environment and improvement of the physical-chemical water quality in recirculating systems. Bacterial strains were isolated for their beneficial effects on survival and growth of aquatic invertebrates (Artemia and rotifers), although the benefits of these bacteria mixes (the ‘probiotic potential’) remain to be evaluated for aquaculture, and particularly for perch culture. However, the research has lead to the commercial production of a bacterial mixture (ABIL aqua 2000) that allows rapid activation of biological filters (in fresh and salt water) and combats unexpected peaks in nitrite concentration, while having a de-nitrifying effect. This mixture therefore has a strong potential in larval rearing of any species in recirculating systems.

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

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