110
L. Horvath
INTRODUCTION
The carp
is one of the most highly prolific fish species, laying up to
1
000 000 fertile eggs at one spawning. In temperate zones carp spawning is
correlated with the season and occurs once in early summer; under subtropical
and tropical conditions, it can occur several times a year because the nætabo—
lism is continuously active. It is important to have precise information on
environmental requirements for the development of sexual products and spawning
which can be used in practical propagation technologies for carp°
THE PROCESS
OF COGENESIS
Carp are so—called warm—water fishes, i.e. they prefer an ambient tempe—
rature
of
20°C for growth, though feeding begins at 8°C under pond conditions
(Schaperclaus, 1967). The decisive role of temperature on sexual naturity is
‘
proved by the fact that females in the tropics are ready for reproduction af—
ter
one
yera
(Bardach et al., 1972), after two years in subtropical climates
(Brunnhubner, 1968), after 3 to 4 years in Southern Europe, and after 4—5
years
in Central Europe (Solewsky, 1958; Woynarovish & Horvath, 1980). A simi—
lar trend has been described by Kuzmin (1957) and Martyshev (1973) in the USSR
Ï
going from south to north (see also Bieniarz, this volume).
The optimal spawning temperature is between 18—and 22°C, though spawnihg
at
14°C under continental conditions has also been reported (Martyshev, 1973).
Spawning activity decreases above 26°C and ceases entirely at 28°C (Mc Crim—
mon,
1963). The carp is a eurytopic warm—water species; temperature, dissolved
oxygen,
nutrient supply, sometimes light conditions and disease (parasites)
&
are
the factors basically influencing gametogenesis. Besides histological
examination, primarily in field—work, a visual procedure is also used to esti'mate
the degree of ovary maturity (Szuvorov, 1948). This includes six more or
less defiùite stages
:
Phase I.
The gonads are underdeveloped; they resemble abords and are attached
to
the wall of the doby Cavity. Visual sex differentiation is impossible—
Phase II.
The
gonads are small. Large blood vessels run over the ovary; there
are
none
in the testis.
,
Phase
III.
The ovaries are fairly big and may fill one—third of the body ca—
v1ty. When the edge of the ovary is cut, the eggs remain together in small
clusters:
When the
edge of the testis is cut, the contents do not flow out.
f
The testis
is pink due to blood vessels.
'
,
'
1
PhaseIV. The gonads are fully developed and may even fill two—thirds of the
3
body cavity,
which is
enlarged. Blood vessels run on the surface of the ovarYThe
follicles are separated from each other. The testis is white; when cut,
mllt flows out. '
i
Phase V. Running stage: the gametes flow out of the gonads.
… F@st—Spawning phase: the body cavity is not full, it is slack. The
1
gonads are inflamed and contain blood clots.
'
d
Visual examination of the ovary is to Some extent a good approach for
ceîeïmining
the state of
the oocytes: However, for more exact studies, the
‘
bî îsZâlca
stages according to Kuzm1n (1957) and Steptoe et al. (1976) can
L. Horvath
INTRODUCTION
The carp
is one of the most highly prolific fish species, laying up to
1
000 000 fertile eggs at one spawning. In temperate zones carp spawning is
correlated with the season and occurs once in early summer; under subtropical
and tropical conditions, it can occur several times a year because the nætabo—
lism is continuously active. It is important to have precise information on
environmental requirements for the development of sexual products and spawning
which can be used in practical propagation technologies for carp°
THE PROCESS
OF COGENESIS
Carp are so—called warm—water fishes, i.e. they prefer an ambient tempe—
rature
of
20°C for growth, though feeding begins at 8°C under pond conditions
(Schaperclaus, 1967). The decisive role of temperature on sexual naturity is
‘
proved by the fact that females in the tropics are ready for reproduction af—
ter
one
yera
(Bardach et al., 1972), after two years in subtropical climates
(Brunnhubner, 1968), after 3 to 4 years in Southern Europe, and after 4—5
years
in Central Europe (Solewsky, 1958; Woynarovish & Horvath, 1980). A simi—
lar trend has been described by Kuzmin (1957) and Martyshev (1973) in the USSR
Ï
going from south to north (see also Bieniarz, this volume).
The optimal spawning temperature is between 18—and 22°C, though spawnihg
at
14°C under continental conditions has also been reported (Martyshev, 1973).
Spawning activity decreases above 26°C and ceases entirely at 28°C (Mc Crim—
mon,
1963). The carp is a eurytopic warm—water species; temperature, dissolved
oxygen,
nutrient supply, sometimes light conditions and disease (parasites)
&
are
the factors basically influencing gametogenesis. Besides histological
examination, primarily in field—work, a visual procedure is also used to esti'mate
the degree of ovary maturity (Szuvorov, 1948). This includes six more or
less defiùite stages
:
Phase I.
The gonads are underdeveloped; they resemble abords and are attached
to
the wall of the doby Cavity. Visual sex differentiation is impossible—
Phase II.
The
gonads are small. Large blood vessels run over the ovary; there
are
none
in the testis.
,
Phase
III.
The ovaries are fairly big and may fill one—third of the body ca—
v1ty. When the edge of the ovary is cut, the eggs remain together in small
clusters:
When the
edge of the testis is cut, the contents do not flow out.
f
The testis
is pink due to blood vessels.
'
,
'
1
PhaseIV. The gonads are fully developed and may even fill two—thirds of the
3
body cavity,
which is
enlarged. Blood vessels run on the surface of the ovarYThe
follicles are separated from each other. The testis is white; when cut,
mllt flows out. '
i
Phase V. Running stage: the gametes flow out of the gonads.
… F@st—Spawning phase: the body cavity is not full, it is slack. The
1
gonads are inflamed and contain blood clots.
'
d
Visual examination of the ovary is to Some extent a good approach for
ceîeïmining
the state of
the oocytes: However, for more exact studies, the
‘
bî îsZâlca
stages according to Kuzm1n (1957) and Steptoe et al. (1976) can