Basic HTML Version
International Journal of Marine Science 2013, Vol.3, No.47, 402-407
http://ijms.sophiapublisher.com
403
area during the period 1997–1998 and 2004–2008.
Samples were collected from the fish market at Al-
seeb area and were directly preserved in cool box with
ice flakes and were analysed on the same day of
sampling. Length, weight, and maturity stages for
each fish were recorded. The weight of the fish was
recorded to the nearest 0.01 g using an electronic
balance (Mettler PE 360) and the length was recorded
to the nearest mm measuring from the tip of the mouth
to the longest lobe of the caudal fin. Sex and maturity
stages of the male and female
S. longiceps
samples
were determined based on the macroscopic
characteristics of the gonads (Nielsen and Johnson,
1995). Fish data were sorted based on sex, length (0.5
cm interval), weight, and maturity stages for both the
sampling periods. The female ratio (F
/
(F
+
M)) was
determined per month and per each length interval. All
the sex ratios thus obtained were tested using chi
square test (
χ
2
) test at 5% significance level to find
whether they were significantly or non-significantly
different from the expected sex ratio of 1:1 or 0.5 rate
(Zar, 1984). Similarly, the maturity stage (I, II, III, IV,
V, and spent) distributions were analysed monthly and
per class interval.
2 Results
During the period 1997–1998, a total of 1799 sardines
were sampled and their total length ranged from 2.5 to
21.3 cm with a mean of 15.3 ± 3.4 cm. In all, 560
male sardines were sampled and their lengths ranged
from 12 to 20.6 cm with a mean of 16.7 ± 1.8 cm. On
the other hand, 905 female sardines were sampled and
their lengths ranged from 10 to 21.3 cm with a mean
of 16.19 ± 2.16 cm. Lengths of male and female
sardines were statistically proved to be not different
(
T
0.05, df = 1463
= 4.79, P
<
0.05). For the 1997–1998
samples, the total weight for the combined sexes
ranged from 0.14 to 91.0 g with a mean of 34.68 ±
0.41 g. The weights of the male sardines ranged from
16.32 to 79.8 g with a mean of 41.34 ± 0.57 g,
whereas for females the weights ranged from 8.21 to
91.0 g with a mean of 38.33 ± 0.52 g. Total weight of
male and female sardines proved to be not statistically
different (
T
0.05, df = 1274
= 5.75, P
<
0.05) (Figure 1).
During the period 2004–2008, a total of 1590 sardines
were sampled ranging from 11.9 to 22 cm in length
with a mean of 16.34 ± 1.84 cm. Their weights ranged
from 14 to 94.6 g with a mean of 42.44 ± 0.38 g. A
total of 1022 female sardines were sampled and their
Figure 1 Frequency distribution of the male and female Omani
Indian oil sardines (
S. longiceps
) for the data samples collected
in 1997-1998 and 2004-2008
lengths ranged from 12.8 to 22 cm with a mean of
16.7 ± 1.72 cm. The length for males (
n
= 568) ranged
from 12.3 to 21.5 cm with a mean of 16.42 ± 1.8 cm.
Length of male and female sardines were proved not
to be significantly different (
T
0.05, df = 1507
= 2.92, P
<
0.05). The total weight for the 2004–2008 samples for
the combined sexes ranged from 14 to 94.6 g with a
mean of 42.44 ± 0.38 g. On the other hand, the
weights of the male sardines ranged from 16.32 to
79.8 g with a mean of 41.34 ± 0.57 g. The weights of
the female sardines ranged from 16.8 to 94.6 g with a
mean of 43.65 ± 0.46 g. Weights of male and female
sardines were proved to be significantly different
(
T
0.05, df = 1507
= 2.59, P
<
0.05). Unlike the 1997–1998
data, no sardines were found below 12.5 cm in the
2004-2008 data (Figure 1).
During both sampling periods, the female sardines
outnumbered the males. The values of the
χ
2
significance test assuming the observed sex ratio is
different from the expected 1:1 or 0.5 rate as given in
Table 1. In the 1997–1998 data, the males dominated
the lower length class from 10 to 11 cm with a
significant difference in the expected sex ratio of 0.5
(P
<
0.01). The females on the other hand dominated
most of the remaining classes significantly (Table 2).