International Journal of Aquaculture, 2015, Vol.5, No.7 1
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6
3
b
, where
Dtrans
is the transformed truss measurement,
D
is the original truss measurement,
BL
is the body
length of fish,
BL
mean is the overall mean of the
body length, and
b
is the within-group slope of the
geometric mean regression calculated with
log-transformed variables,
D
and
BL
.
2 Results and Discussion
2.1
Length-weight relationship
The length-weight relationship of
P. sextarius
was
found to be
W
Po
=
1.17
L
1.46
, while for
N. japonicus
and
P. argenteus
was estimated as
W
Ne
=
0.07
L
2.73
and
W
Pa
=
0.04
×L
3.05
respectively (Table 2).
Table 2 Length-weight relationship of
P. sextarius, N. japonicas
and
P. argenteus
collected from Fiery Cross Reef, South China
Sea
Fish species
a
b
R
2
Polydactylus sextarius
1.17
1.46
0.78
Nemipterus japonicus
0.07
2.73
0.69
Pampus argenteus
0.04
3.05
0.80
Wang et al. (2011) found that the
b
value of
P.
sextarius
was 2.90, and suggested that the fish
followed a negative allometric growth pattern (
b
< 3).
In the present study, we got the same conclusion
despite Wang et al. (2001)’s exponent ‘b’ value was
greater than ours (
b
= 1.46). In the present study
smaller ‘b’ values (b=1.46) was due to the analysis of
restriced length range (119.43-100.36=19. 7 mm) and
low fish number (66), which not covered all the size
groups. The
b
values in the length-weight relationship
of
N. japonicus
from Jizan Region of Red Sea, Suez
Gulf-Red Sea and Afshari in the Northren Oman Sea
were ranged from 2.6 to 2.8 (Bakhsh, 1996; Amine,
2012; Afshari et al., 2013). In this study, the
b
value of
N. japonicus
obtained from Fiery Cross Reef was 2.73,
which showed similarities with their study suggesting
a negative allometric growth in this species. However,
Manojkumar et al. (2004) (
b
= 2.9902), and Raje
(2003) (
b
= 3.00437) were isometric and highly
differed with the present study.
Siyal and Amir
(2012) estimated the length-weight
relationship in
P. argenteus
from Pakistan waters and
got the exponent b value 3.15, which was closer to
present study, and the growth was found to be
isometric. However, the
b
value in the length-weight
relationship of
P. argenteus
estimated in the Bay of
Bengal Large Marine Ecosystem was 2.841 (Siyal and
Amir, 2012). The
b
value of this species collected
along the southern coast of Karnataka, India was
2.485 (Abdurahiman
et al., 2004). Both results
indicated that the growth of
P. argenteus
followed
negative allometric trend. The difference between ‘b’
values of our study and other researchers’ study might
be due to the fish growth phase, size range, small and
big data range, seasonal effect, general fish condition
and size selectivity of the sampling gear (Tesch et al.,
1971).
2.2
Truss network analysis
Body length of
P. sextarius
varied from 100.36 to
119.43 mm, and the wet weight ranged from 10.04 to
45.42 g. Body length of
N. japonicus
varied from
88.37 to 159.54 mm, wet weight ranged from 22.42 to
128.39 g. Body length of
P. argenteus
varied from
75.13 to 92.07 mm, and wet weight ranged from 20.58
to 42.27 g (Table 1). All models of truss networks are
presented in Figure 1. Morphometric trait has been
used for the identification of fish stock units as a
powerful measurement tool (Cadrin and Friedland ,
1999). Cadrin (2000) suggested that morphmetric
variations can be used to discriminate the stock units,
as the result may be different when locations are
changed. Furthermore, Nie et al. (2014) successfully
removed the size effect by allometric transformation
of their study data.
In conclusion, our study identified the morphological
characters of
P. sextarius
,
N. japonicus
and
P.
argenteus
collected from Fiery Cross Reef of South
China Sea, we measured 39 morphological characters
between 12 landmarks of
P. sextarius
, 29 characters
between 10 landmarks of
N. japonicus
and 23
characters between 9 landmarks of
P. argenteus
for
academic work. For detail measurement, all characters
from significant loadings obtained shown in Table 3,
and all of these may be be useful as primary
measurement characters.
Acknowledgements
This project was funded by National Infrastructure of Fishery
Germplasm Resources Project.
References
Abdurahiman K. P., Nayak T. H., Zacharia P. U. and Mohamed K. S. 2004,
Length-weight relationship of commercially important marine fishes
and shellfishes of the southern coast of Karnataka, India.
J. NAGA,
World Fish Centre Quarterly
, 27(1 & 2): 9-14
