A recirculation system for
high-density rotifer production
Aquaflow Technical Leaflet 2003-115
European Network for the Dissemination of Aquaculture
RTD Information (Q5CA-2000-30105) and previously FAIR-3837, URL: http://www.aquaflow.org/
The project consisted in designing a high density
rearing technique using a newly-developed artificial diet for the rotifer Brachionus
plicatilis. An appropriate recirculation system (including settlement
tank, biological filter and additional water purification systems including
protein skimmers and ozone treatment) was designed to maintain optimal water
quality during the rearing procedure and hence reduce manipulation and
stress of the rotifer population. The use of a high quality diet and the
application of the recirculation culture system resulted in nutritionally
and microbiologically high quality rotifers. Besides the biological
advances, the new concept has several industrial implications, not the least
by an expected tenfold increase in production at a reduced labour cost.
A pilot scale rotifer recirculation system was
constructed in which the rearing tank, the filter material, the protein
skimmer, the ozone and the biofilter were tested. A new system was developed, which facilitates and automates
the rotifer harvest. Flock filters in rotifer tanks were tested to decrease
the occurrence of flocks inside the rotifer tanks. A CD-Rom was made with
the documentation on the functioning of the rotifer recirculation system
with practical exercises.
Two prototypes of the rotifer recirculation system
were constructed in Italy (seabream and seabass hatchery) and in Norway (for
cod production). The seabream trial in Italy compared rotifers cultured in
batch and recirculation systems. The recirculation system functions well for
the Italian rotifer strain, with mesh sizes used during these trials (50 µm
screen for the outlet filter). The nutritional and microbial quality of the
rotifers (length, stress resistance, survival, deformity and biomass
production of the larvae) cultured in the recirculation system was
comparable with the ones from batch culture.
The economical and social impact of the rotifer
recirculation system was studied based on literature and practical
information coming from commercial hatcheries. The total cost for producing
rotifers in a recirculation system is considerably lower than in batch
system (about 30%). Within the global costs of the recirculation system, the
relation between the different costs is similar to batch culture, except for
the cost for feed and labour. When expressed in percentages the cost for
feed is increasing using the recirculation system, but on absolute basis,
the cost for feed remains identical to the batch system. However, the labour
cost is considerably reduced - one person working 2 hours a day can easily
handle two rotifer recirculation systems; the work being less stressful and
physically less heavy. Most importantly, the rotifer production is more
reliable by its clean and healthy production.
For more information:
Tania
De Wolf
Inve Technologies NV
Oeverstraat 7,
B-9200 Baasrode - Belgium
Tel.: +32 (0) 52 33 13 20
Fax: +32 (0) 52 33 45 31
E-mail: t.de_wolf@inve.be