International Journal of Aquaculture, 2016, Vol.6, No.6, 1
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small oocytes are found, which are recruitment stock eggs in spent ovary unabsorbed and give rise to mature eggs
during the following season. The ovarian wall is folded. This stage found from January to April (Figure 7).
Figure 5 Cross section of ovary showing
Mature stage
of
Liza
carinata
stained with
eosin and hematoxilin
(10X)
Figure 6 Cross section of ovary showing
Spawning stage
of
Liza carinata
stained with
eosin and hematoxilin
(10X)
Figure
7
Cross section of ovary showing
Spent stage
of
Liza carinata
stained with
eosin and hematoxilin
(10X)
3.2 Gonadosomatic index (Reproductive period)
Monthly variations in GSI of female
L. carinata
were quite apparent (Figure 8). Considerable increase of GSI
value was recorded from November (7.05% ±0.729) followed by maximum increase in December (8.88 % ±
0.867), a slight decrease occurred in January followed by a considerable drop in March (0.62 % ±0.179) and
reach minimum levels in May (0.397% ±0.047). From September onwards the values of GSI increased. These
cyclic changes in GSI indices are considered as further a proof that the spawning season is extending from
November to March (Figure 8).
3.3 Sex Steriod Hormones
17β - Estradiol levels in female
L. carinata
ranged from maximum value 0.199 ±0.087 ng / ml recorded in November
2012 to 0.102 ±0.016 ng / ml ml in December 2012. Estradiol levels were low from March but afterward they increased
significantly in October 2013 (Figure 9).
Testosterone levels in female
L. carinata
ranged from 29.7.5 ±4.922 ng / ml to 26.9 ±2.807 ng / ml in November
2012 to October 2013 (Figure 9). The lowest value of testosterone was observed in February 2013 (17.4 ±1.054)
in spawning and spent stages of maturity. Increasing of testosterone levels was recorded as long as the maturation
of ovary increase to reach its highest value in December 2012 (30.5 ± 2.037 ng / ml) where mature stage of
ovaries (Table 1).
4 Discussions
The histological studies demonstrated that there are two developmental phases of the oocyte namely, the primary
