320
Aquaculture of Cyprinids
METEOROLOGICAL
INŒACT ON CARP PRODUCTION IN FONDS.
M…A. SZUMIEC,
Cwüwœ
Exp…cmÆœ@ Siæt£on GOÆgAt, 43—422 Chych, POLAND.
Optimizing up—to—date carp farming needs full knowledge of environmental
impact on carp. Evaluation of the alterations in ponds caused by weather
changes is complicated by the influence of different pond morphometries, fish
intensification levels and the considerable reverse effect of biotope on the
physical environment. Long—term research in this field carried out at the
Golysz Station allo—ed us to determine weather impact, typical of a temperate
climate, on the two most important factors in the carp physical environment:
water
temperature and the solar radiation penetrating the ponds. Time—verti—
cal
temperature distribution in ponds, as a function of air temperature, and
a
time—vertical solar radiation flux penetrating the ponds, as a function
of
radiation teaching the water surface, were empirically studied. It was
found
that the
temperature effective for carp growth ranges from 13 to 14°C ;
it drops slightly when full—value food is used. The approximately linear
relation between carp growth and effective water temperature, as well as the
relation between air and water temperatures, make it possible to predict
carp
growth rate based on meteorological data. With rapid and full overcasting during the warm months, the solar radiation flux penetrating the inten—
sively managed ponds may limit plant photosynthesis and thereby carp survi—
val.
Such a condition
can
be predicted even during sunny days : it appears
when the solar radition flux in ponds falls below 0.2 cal/cmZ/min( ca 0.014 W
cm—2) at a depth of 20 cm or when the Secchi disc disappears at 15/20 cm.
These are basic facts in the development of aquacultural meteorology which,
as
an
applied science, may protect carp farmin from unfavourable weather
when the proper meteorological forecasts and warnings are used. Fish loss
can
be avoided and.moreefficient farming methods introduced by adapting carp
rearing biotechniques to meteorological conditions.
THE EFFECT OF BOTTOM PLOWTNG ON SOME ECOLOGTCAL PARAMETERS
IN CARP FONDS.
].
VERRETH, S. JASPERSE, R. BAKKER, and R.RÔIJACKÈRS. DepaäÆmen£ 06 FÀAh
Cwüîwœ and Im£and FMhQJIÀQÀ, AgMcuüuc UMUQ/ŒÂÂÎg, P.O.B. 338, (dagcm'ngcm
THE NETHERLANDS
.
Dutch winters are very mild and humid. Winter drying of pond bottom soils
seems
not
very effective. After more than twenty years of semi—iûüensive
carp culture
the ecosystem of the ponds seemed to be vert destabilized,
resulting in heavy disease problems and lower yields. Certain aspects indicated a possible role of the pond bottom soils. Therefore the bottom.of some
ponds were plowed at early autumn. During the coarse of the following year
several
ecological parameters were compared between ponds with and without
a
plowed bottom. In general plowing resulted in a better oxygenation and in
a
very light structure of the pond bottom soil. Due to the oxygenation the
eventual effect of toxic reduced substances can be avoided. The light soil
structure
resulted in lower light incidence (and consequently lower gross
photosynthesis) and in a better susceptibility of chironomids to carp predation.
RRELIMINARY OBSERVATIONS OF FISH GROWTH AND EVOLVING WATER QUALITY IN A COM—
MON OARP
AND BLUE TILAPIA HIGH PRODUCTION POND.
R.D.
ZWEIG, The New A£chemy
lnAïXiuäe, 237 HŒÉQhVÀKKQ Road, EaAï Fa£mou£h, MA 02536,U.S.A.
In many regions of
the world, pond fish culture can only be conducted part
of
the year
due
to
either low seasonal temperatures or water availability
In many instances, power sources to drive aerators or water pumps are unavai—
Aquaculture of Cyprinids
METEOROLOGICAL
INŒACT ON CARP PRODUCTION IN FONDS.
M…A. SZUMIEC,
Cwüwœ
Exp…cmÆœ@ Siæt£on GOÆgAt, 43—422 Chych, POLAND.
Optimizing up—to—date carp farming needs full knowledge of environmental
impact on carp. Evaluation of the alterations in ponds caused by weather
changes is complicated by the influence of different pond morphometries, fish
intensification levels and the considerable reverse effect of biotope on the
physical environment. Long—term research in this field carried out at the
Golysz Station allo—ed us to determine weather impact, typical of a temperate
climate, on the two most important factors in the carp physical environment:
water
temperature and the solar radiation penetrating the ponds. Time—verti—
cal
temperature distribution in ponds, as a function of air temperature, and
a
time—vertical solar radiation flux penetrating the ponds, as a function
of
radiation teaching the water surface, were empirically studied. It was
found
that the
temperature effective for carp growth ranges from 13 to 14°C ;
it drops slightly when full—value food is used. The approximately linear
relation between carp growth and effective water temperature, as well as the
relation between air and water temperatures, make it possible to predict
carp
growth rate based on meteorological data. With rapid and full overcasting during the warm months, the solar radiation flux penetrating the inten—
sively managed ponds may limit plant photosynthesis and thereby carp survi—
val.
Such a condition
can
be predicted even during sunny days : it appears
when the solar radition flux in ponds falls below 0.2 cal/cmZ/min( ca 0.014 W
cm—2) at a depth of 20 cm or when the Secchi disc disappears at 15/20 cm.
These are basic facts in the development of aquacultural meteorology which,
as
an
applied science, may protect carp farmin from unfavourable weather
when the proper meteorological forecasts and warnings are used. Fish loss
can
be avoided and.moreefficient farming methods introduced by adapting carp
rearing biotechniques to meteorological conditions.
THE EFFECT OF BOTTOM PLOWTNG ON SOME ECOLOGTCAL PARAMETERS
IN CARP FONDS.
].
VERRETH, S. JASPERSE, R. BAKKER, and R.RÔIJACKÈRS. DepaäÆmen£ 06 FÀAh
Cwüîwœ and Im£and FMhQJIÀQÀ, AgMcuüuc UMUQ/ŒÂÂÎg, P.O.B. 338, (dagcm'ngcm
THE NETHERLANDS
.
Dutch winters are very mild and humid. Winter drying of pond bottom soils
seems
not
very effective. After more than twenty years of semi—iûüensive
carp culture
the ecosystem of the ponds seemed to be vert destabilized,
resulting in heavy disease problems and lower yields. Certain aspects indicated a possible role of the pond bottom soils. Therefore the bottom.of some
ponds were plowed at early autumn. During the coarse of the following year
several
ecological parameters were compared between ponds with and without
a
plowed bottom. In general plowing resulted in a better oxygenation and in
a
very light structure of the pond bottom soil. Due to the oxygenation the
eventual effect of toxic reduced substances can be avoided. The light soil
structure
resulted in lower light incidence (and consequently lower gross
photosynthesis) and in a better susceptibility of chironomids to carp predation.
RRELIMINARY OBSERVATIONS OF FISH GROWTH AND EVOLVING WATER QUALITY IN A COM—
MON OARP
AND BLUE TILAPIA HIGH PRODUCTION POND.
R.D.
ZWEIG, The New A£chemy
lnAïXiuäe, 237 HŒÉQhVÀKKQ Road, EaAï Fa£mou£h, MA 02536,U.S.A.
In many regions of
the world, pond fish culture can only be conducted part
of
the year
due
to
either low seasonal temperatures or water availability
In many instances, power sources to drive aerators or water pumps are unavai—