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International Journal of Marine Science 2013, Vol.3, No.47, 402-407
http://ijms.sophiapublisher.com
402
Research Article Open Access
Sex Ratio Variation of the Omani Indian Oil Sardine
Sardinella longiceps
(Valenciennes, 1847)
Saud Musallam S. Al-Jufaili
Department of Marine Science and Fisheries, College of Agricultural and Marine Sciences, Sultan Qaboos University, PO Box 34, Al-Khod 123, Muscat,
Sultanate of Oman.
Corresponding author email:
sjufaily@squ.edu.om
International Journal of Marine Science, 2013, Vol.3, No.47 doi: 10.5376/ijms.2013.03.0047
Received: 03 Aug., 2013
Accepted: 05 Sep., 2013
Published: 05 Nov., 2013
Copyright
©
2013 Al-Jufaili, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Al-Jufaili, 2013, Sex Ratio Variation of the Omani Indian Oil Sardine
Sardinella longiceps
(Valenciennes, 1847), International Journal of Marine Science,
Vol.3, No.47 402
-
407 (doi: 10.5376/ijms.2013.03.0047)
Abstract
During the period 2004–2008, a total of 1590 (1022 females and 568 males) Omani Indian oil sardines (
Sardinella
longiceps
) were monthly sampled from a major landing site in Al-Seeb, Sultanate of Oman, to determine sex ratio. The results were
compared with the results of a previous sampling study conducted in 1997–1998 in the same area, in which 1799 sardines (905
females and 560 males) were sampled, the rest were not sexed. During the period 2004–2008, the total length of female sardines
ranged from 12.8 to 22 cm with a mean of 16.7 ± 1.72 cm and their total weight ranged from 16.8 to 94.6 g with a mean of 43.65 ±
0.46 g. Male sardines ranged from 12.3 to 21.5 cm in length with a mean of 16.42 ± 1.8 cm and their weights ranged from 16.32 to
79.8 g with a mean of 41.34 ± 0.57 g. During 1997–1998, female sardines ranged from 10 to 21.3 cm in length with a mean of 16.19
± 2.16 cm and their weights ranged from 8.21 to 91.0 g with a mean of 38.33 ± 0.52 g. The male sardines ranged from 12 to 20.6 cm
in length with a mean of 16.7 ± 1.8 cm and their weights ranged from 16.32 to 79.8 g with a mean of 41.34 ± 0.57 g. The monthly
sex ratios fluctuated between 0.45 and 1 with a mean of 0.63 ± 0.04 in 1997–1998 samples and between 0.29 and 0.98 with a mean of
0.68 ± 0.02 in 2004–2008 samples. The overall sex ratios during 1997–1998 and 2004–2008 were 0.62 and 0.64, respectively. Both
the sex ratios were different from the expected sex ratio of 0.5 according to the
χ
2
test (P-value
<
0.01). The relationship between sex
ratio and length was explained by the power function as (sex ratio = 0.002
L
2.03
,
r
= 0.92) for the period 1997–1998 and by (sex ratio
= 6.7×10
-6
L
6.84
,
r
= 0.96) for 2004–2008. The results indicated faster female growth rate and higher abundance of female over the
males in the fishing grounds.
Keywords
Oman; Indian oil sardine; Sex ratio; Maturity stages
Introduction
The Omani Indian oil sardine
Sardinella longiceps
fishery is one of the important traditional fisheries
along the Omani coast. Among other sardines found off
the Omani waters, the Indian oil sardines contribute the
most to the catch composition of the small pelagic
(Dorr III et al., 1990). The sardine fishery in Oman is a
market-driven business and fishermen usually target
sardines using beach seines, gillnet, and occasionally
purse seines. Sardines in Oman are used for human
consumption, as fertilizer, and as food for cattle
(Mahgoub et al., 2005).
Despite the importance of the Omani traditional coastal
fisheries, less work has been done regarding the stock
assessment of this fish.. This paper analyses and
compares the sex ratio of the Omani Indian oil sardine
using data obtained by the author during 1997–1998
and 2004–2008. Sex ratio studies are important and
provide basic yet vital information for assessing the
reproductive condition of the fish stock (Wang et al.,
2003; Vicentini and Araújo, 2003). In addition, sex
ratio parameters are important in building up the
knowledge of the fish sex distribution behaviour before,
during, and after the spawning periods. Furthermore,
studies related to fish sex determination are important
for calculating the spawning stock biomass per size
class (Foale and Day, 1997; Chiang et al., 2006). The
results from studies conducted on sex ratios of the same
fish vary due to many factors such as time of the study,
sampling methods, and environmental conditions
(Nikolsky, 1963).
1 Material and Methods
Sardine samples were collected from a beach seine
fishery randomly and monthly from Al-Seeb landing