Poster summaries
317
POND FISH CULTURE
IN LA SOLOGNE AND LA BRENNE, TWO REGIONS OF THE MIDDLE OF
FRANCE.
J.F.
MARTIN, Dé@êgæton &êg£omæ€e à £'Aquacu£ïMc, CLiê
fève C0ügny, 45042 OÆ€êan, FRANCE.
The natural regions of Sologne and Brenne have 3.300 ponds, making a total
of
17,000 ha of water. 602 of the total production (1,600 t/year) of carp
(Cyprinus carpio), reach (Rutilus rutilus) and tench (Tinoa tinca) is used
for re—stocking and 40% for consumption. This production varies between 40
and
900 Kg/ha. Mean yield is low, being about 85 Kg/ha. The main reasons
for
this are the low natural water productivity (acid water containing few
nutritive elements), poor pond and water management. To better use this fish
farming potential the economic development of these underprivileged regions,
it is necessary to improve pond yiels; this can be done if the physico—
chemical composition of the water is modified by adding quick—activing
minerals suited to the particular water types in these
environment. Ferti—
lization rate is based on a formula computing the amounts of calcium to add,
depending on the economic optimum desired and the sediment reaction to these
mineral supplies. Also, studying the pond's types of these regions and
determining their yield's factors should make it possible to manage this
aquatic wealth more efficiently. Mineral fertilization, even though well
managed and of absolute necessity due to the lack of nutrient available in
the ponds, is very costly and of limited efficiency, considering the energy
loss in the trophic system of the pond and the fish Species producted (no
herbivorous or phytoplancktonophagic fish) in a production system which can
only be extensive due to lack of water control and slight marketing possibi—
lities. Thus the prospect of integrating aquaculture into the farm land
culture would improve the economic and ecological interests of these regions
creating productive activities and using their wastes to improve pond yield.
CITY SEWAGE FISH FONDS
IN HUNGARY AND INDIA.
J
.
OLAH, N. SARANGI, and N.C.
DATTA. FÂAhQÆÀQA RQAQŒÆCh Inbïiiuie, H 5540 SZARVAS, HUNGÀRV.
The management parameters and culture techniques used in domestic sewage
oxidation fish—ponds in Hungary and sewage—fed fisheries in Calcutta (India)
have been compared along with physico—chemical parameters and nutrient
status
in terms of biological productivity. The environment supporting heal—
thy fish growth was more stabile in Hungarian oxidation_ponds due to the
daily introduction of sewage. Biel oxigen ranged between 4—19 in the Hunga—
rian fishponds and between 3.2—16.4 mg/l in the Indian ponds. The highest
total ammonia was 0.9 and 3.6 mg/l. Natural fish food resources such as
zooplanckton reached the same maxima (around 11 COO/l) but chironomids and
oligochaetes were more abundant in the Indian ponds with maxima of 22 and
35 OOO/m2. Fish production was considerably higher in the tropical zone
(21.3 Kg/day) compared to the temperature zone (12.0 Kg ha/day) with
production efficiencies (in terms of percent of primary production converted
to
fish) of 2.7 and ].5—5.2, respectively. The results of both groups of
ponds are presented as well as the selection of species, stocking structure
and density, manipulation, period of rearing and implementation possibilities
of the
technique in tropical and temperate urbanised areas having consideraf
ble sewage production.
317
POND FISH CULTURE
IN LA SOLOGNE AND LA BRENNE, TWO REGIONS OF THE MIDDLE OF
FRANCE.
J.F.
MARTIN, Dé@êgæton &êg£omæ€e à £'Aquacu£ïMc, CLiê
fève C0ügny, 45042 OÆ€êan, FRANCE.
The natural regions of Sologne and Brenne have 3.300 ponds, making a total
of
17,000 ha of water. 602 of the total production (1,600 t/year) of carp
(Cyprinus carpio), reach (Rutilus rutilus) and tench (Tinoa tinca) is used
for re—stocking and 40% for consumption. This production varies between 40
and
900 Kg/ha. Mean yield is low, being about 85 Kg/ha. The main reasons
for
this are the low natural water productivity (acid water containing few
nutritive elements), poor pond and water management. To better use this fish
farming potential the economic development of these underprivileged regions,
it is necessary to improve pond yiels; this can be done if the physico—
chemical composition of the water is modified by adding quick—activing
minerals suited to the particular water types in these
environment. Ferti—
lization rate is based on a formula computing the amounts of calcium to add,
depending on the economic optimum desired and the sediment reaction to these
mineral supplies. Also, studying the pond's types of these regions and
determining their yield's factors should make it possible to manage this
aquatic wealth more efficiently. Mineral fertilization, even though well
managed and of absolute necessity due to the lack of nutrient available in
the ponds, is very costly and of limited efficiency, considering the energy
loss in the trophic system of the pond and the fish Species producted (no
herbivorous or phytoplancktonophagic fish) in a production system which can
only be extensive due to lack of water control and slight marketing possibi—
lities. Thus the prospect of integrating aquaculture into the farm land
culture would improve the economic and ecological interests of these regions
creating productive activities and using their wastes to improve pond yield.
CITY SEWAGE FISH FONDS
IN HUNGARY AND INDIA.
J
.
OLAH, N. SARANGI, and N.C.
DATTA. FÂAhQÆÀQA RQAQŒÆCh Inbïiiuie, H 5540 SZARVAS, HUNGÀRV.
The management parameters and culture techniques used in domestic sewage
oxidation fish—ponds in Hungary and sewage—fed fisheries in Calcutta (India)
have been compared along with physico—chemical parameters and nutrient
status
in terms of biological productivity. The environment supporting heal—
thy fish growth was more stabile in Hungarian oxidation_ponds due to the
daily introduction of sewage. Biel oxigen ranged between 4—19 in the Hunga—
rian fishponds and between 3.2—16.4 mg/l in the Indian ponds. The highest
total ammonia was 0.9 and 3.6 mg/l. Natural fish food resources such as
zooplanckton reached the same maxima (around 11 COO/l) but chironomids and
oligochaetes were more abundant in the Indian ponds with maxima of 22 and
35 OOO/m2. Fish production was considerably higher in the tropical zone
(21.3 Kg/day) compared to the temperature zone (12.0 Kg ha/day) with
production efficiencies (in terms of percent of primary production converted
to
fish) of 2.7 and ].5—5.2, respectively. The results of both groups of
ponds are presented as well as the selection of species, stocking structure
and density, manipulation, period of rearing and implementation possibilities
of the
technique in tropical and temperate urbanised areas having consideraf
ble sewage production.