Basic HTML Version
Inter. J. of Marine Science 2012, Vol.2, No.4, 24-30
http://ijms.sophiapublisher.com
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Figure 4 Gonad maturation for ripe running (RR) and spent
fishes over the period March 2009 ~ February 2010 for
S. sutor
females (n = 107)
Note: Ns: no sample collected
Figure 5 Mean GSI (±: standard error) by lunar phase for
November and December 2010 samples of
S. sutor
females (n
= 99)
Note: X-axis labels denote lunar phase: new moon (NM)
starting on LD 1; First quarter (FQ) starting on LD 9; Full
moon (FM) starting on lunar day (LD) 16; and last quarter (LQ)
starting on LD 23); Numbers above bars are sample sizes
with the highest proportion of ripe ovaries (RI)
observed in the full moon phase, whereas running ripe
(RR) or hydrated ovaries dominated samples in the
first quarter (Figure 6). Resting (RE) ovaries predominated
in the last quarter. Imminent spawning was confirmed
by the presence of hydrated oocytes, which were
observed primarily during the first quarter and to a
lesser extent during full moon (Figure 6). Some ovaries
had post-ovulatory follicles providing evidence of
very recent spawning. These were observed in samples
collected in the last week of the month of November
2010 GSI value Kruskal-Wallis test showed significant
differences in GSI between moon phases (p<0.05).
Nonetheless, hydrated ovaries were found in three of
four lunar phases, while post-ovulatory follicles were
observed in all lunar phases except the full moon
phase, suggesting spawning in this species is protracted.
Ovarian maturity stages are illustrated in Figure 7.
Figure 6 Gonad maturation by lunar phase over a lunar cycle in
November and December 2010 for
S. sutor
females (n = 85)
Note: Numbers above bars are sample sizes. X-axis labels
denote lunar phase as defined in Figure 5
Figure 7 Gonad transverse sections showing different maturity
stages of
Siganus sutor
ovaries
Note: A: Immature, B: Mature, C: Mature resting, D: Mature,
E : Spent, F: Running ripe
The minimum size at first maturity,
L
50
, the size at
which 50% of females that were reproductively active,
termed the effective maturity was estimated to be
28.2 cm TL (Figure 8).