Poster summaries
,
1 69
the carp.
However, the evidence for its actual involvement in this process
is incomplete. The present study describes the relationship between stages
of oocyte maturation and the profile of 17,20—P and estradiol (EZ) in Spaw—
ning carp. Fish were primed by injection of pituitary extract containing
0.07 mg IR—cGTH/Kg bw, and 1] hr later were injected with the main dose
(0,35 mg/Kg)of the same. Blood and ovarian biopsies were taken at intervals.
Fish which received the main dose only, the priming dose only or saline
served as
controls.
Ovulation occurred only in fish subjected to the two
injections° Increase in circulating EZ from 0.6 1 0.1 to 8.7 1 1.0 ng/ml
(mean i SEM ; n = 9) occurred after the first injection in fish containing
oocytes with eccentric germinal vesicle (GV). The priming was followed by the
migration of the GV to a peripheral position. Fish containing oocytes with
peripheral GV responded to the second injection by a decrease in EZ level
(3.6 : 1.0 ng/ml), a dramatic but transient increase in 17,20—P (from 0.4 1
0.1
to
110.0 1
14.6 ng/ml) and GV breakdown (GVBD) followed by ovulation.
Ovarian follicles containing oocytes with eccentric (30%) and peripheral
(70%) GVs secreted in_vitro E2 and testosterone (T). Ovarian follicles
containing oocytes with GVBD (76%) taken 4 hrs later from the same female
Secreted mainly 17,20—P and T. lt is concluded that 17,20—P is the maturation
inducing steroid in the carp and is secreted transiently by follicles approa—
ching GVBD.
INDUCED SPAWNÎNG OF INDIAN MAJOR CARPS AT NEEMGACHI, BANGLADESH. D.]. MÀCÏN—
TOSH and C.R. PRICE, lMÆuÆc 06 AqùdcuüMc, U)æévchAüy 05 Sûhng,
SLUŒŒg Scaüand, U.K.
Although the induced spawning of carp species is a well established practice
in Bangladesh, there are few hatcheries in the central and northern regions
of the country and demand of carp fry far exceeds supply. Experience at the
Neemgachi Fish Culture Project in spawning Labeo rohita (rohu), Cirrhinus
mrigala (mrigal) and Labeo calbasu (calabaush) is reported here. Using mainly
fish from village tanks (water reservoirs of 0.4 to 2 ha) or shallow ponds
receiving little or no fertilizers or feeds, spawning success for each spe—
cies in 1983 was as follows
:
rohu
(68 females—67.6Z spawning success);
mrigal (39 females—79.52); calabausch (15 females—100%). Catla catla which
were
also
cultured, did not mature. The fish spawned ranged from 0.5 to 3 Kg
in weight. Total egg production was estimated to be 9,050,000 from which
5,980,000 hatchlings were obtained (survival rate 66%). Spawners were inje—
cted with pituitary gland extract from rohu and mrigal donors caught when
the tanks were fished prior to the breeding season. Human Chorionic Gonado—
tropin (HCG) was also added to the injection. The usual dosages used were:
-
for females of
1
Kg 0.7 to 1.0 pituitary gland
+
150-200 IU HCG
injection) followed by ]_0 to 1_5 gland
+
150—200 IU HCG (second injection
after 6 hours); for males of 1 Kg 0,5 gland
+
100
IU HCG at the
time
of
the
second female injection. These dosages were inbreased by 50% per Kg body
weight for fish weighing more than 1 Kg. Females spawned
8 hours after
üœ second injection (water temperature 26—27°C). A few mr1gal and calabaush
females spawned within 3—4 hours after receiving the first 1DJeCË10H:
FlSh
that had not spawned within 8 hours of the second injection
were
Stripped
Hmnually. In spawning tests conducted in 1984 and 1985 it was found
that the
mmbination of pituitary extract from locally available donor fish plus HCG
Was more
effective than pituitary gland extract or HCG alone or commerc1allY
SuPplied fish pituitary gland preparations.
,
1 69
the carp.
However, the evidence for its actual involvement in this process
is incomplete. The present study describes the relationship between stages
of oocyte maturation and the profile of 17,20—P and estradiol (EZ) in Spaw—
ning carp. Fish were primed by injection of pituitary extract containing
0.07 mg IR—cGTH/Kg bw, and 1] hr later were injected with the main dose
(0,35 mg/Kg)of the same. Blood and ovarian biopsies were taken at intervals.
Fish which received the main dose only, the priming dose only or saline
served as
controls.
Ovulation occurred only in fish subjected to the two
injections° Increase in circulating EZ from 0.6 1 0.1 to 8.7 1 1.0 ng/ml
(mean i SEM ; n = 9) occurred after the first injection in fish containing
oocytes with eccentric germinal vesicle (GV). The priming was followed by the
migration of the GV to a peripheral position. Fish containing oocytes with
peripheral GV responded to the second injection by a decrease in EZ level
(3.6 : 1.0 ng/ml), a dramatic but transient increase in 17,20—P (from 0.4 1
0.1
to
110.0 1
14.6 ng/ml) and GV breakdown (GVBD) followed by ovulation.
Ovarian follicles containing oocytes with eccentric (30%) and peripheral
(70%) GVs secreted in_vitro E2 and testosterone (T). Ovarian follicles
containing oocytes with GVBD (76%) taken 4 hrs later from the same female
Secreted mainly 17,20—P and T. lt is concluded that 17,20—P is the maturation
inducing steroid in the carp and is secreted transiently by follicles approa—
ching GVBD.
INDUCED SPAWNÎNG OF INDIAN MAJOR CARPS AT NEEMGACHI, BANGLADESH. D.]. MÀCÏN—
TOSH and C.R. PRICE, lMÆuÆc 06 AqùdcuüMc, U)æévchAüy 05 Sûhng,
SLUŒŒg Scaüand, U.K.
Although the induced spawning of carp species is a well established practice
in Bangladesh, there are few hatcheries in the central and northern regions
of the country and demand of carp fry far exceeds supply. Experience at the
Neemgachi Fish Culture Project in spawning Labeo rohita (rohu), Cirrhinus
mrigala (mrigal) and Labeo calbasu (calabaush) is reported here. Using mainly
fish from village tanks (water reservoirs of 0.4 to 2 ha) or shallow ponds
receiving little or no fertilizers or feeds, spawning success for each spe—
cies in 1983 was as follows
:
rohu
(68 females—67.6Z spawning success);
mrigal (39 females—79.52); calabausch (15 females—100%). Catla catla which
were
also
cultured, did not mature. The fish spawned ranged from 0.5 to 3 Kg
in weight. Total egg production was estimated to be 9,050,000 from which
5,980,000 hatchlings were obtained (survival rate 66%). Spawners were inje—
cted with pituitary gland extract from rohu and mrigal donors caught when
the tanks were fished prior to the breeding season. Human Chorionic Gonado—
tropin (HCG) was also added to the injection. The usual dosages used were:
-
for females of
1
Kg 0.7 to 1.0 pituitary gland
+
150-200 IU HCG
injection) followed by ]_0 to 1_5 gland
+
150—200 IU HCG (second injection
after 6 hours); for males of 1 Kg 0,5 gland
+
100
IU HCG at the
time
of
the
second female injection. These dosages were inbreased by 50% per Kg body
weight for fish weighing more than 1 Kg. Females spawned
8 hours after
üœ second injection (water temperature 26—27°C). A few mr1gal and calabaush
females spawned within 3—4 hours after receiving the first 1DJeCË10H:
FlSh
that had not spawned within 8 hours of the second injection
were
Stripped
Hmnually. In spawning tests conducted in 1984 and 1985 it was found
that the
mmbination of pituitary extract from locally available donor fish plus HCG
Was more
effective than pituitary gland extract or HCG alone or commerc1allY
SuPplied fish pituitary gland preparations.