Basic HTML Version
International Journal of Marine Science 2014, Vol.4, No.31
http://ijms.biopublisher.ca
4
of the total catch. The other age groups were
represented by relatively very low percentage for both
species. Age readings indicated that the both species
attain their highest growth rate in length during the
first year of life, after which a gradual decrease in
growth increment was observed with further increase
in age (Figure 5).
Figure 4 Age composition of
Hipposcarus harid
and
Chlorurs
sordidus
from Hurgada.
2.2 Total length–scale radius relationship
The TL-R relationship for both
H. harid
and
C.
sordidus
was found to be linear (Figure 3) and
represented by the following equations:
H. harid:
L = 2.6019 R + 1.8501 (r
2
= 0.94, n = 1000)
C. sordidus:
L = 1.1463 R + 9.2601 (r
2
= 0.92, n =
700).
2.3 Length – weight relationship and growth in
weight
The length and weight measurements of 1000
specimens of
H. harid
and 700 specimens of
C.
sordidus
were used for the estimation of length weight
relationship.
H. harid
varied in total length from 17 to
50 cm and in weight from 70 and 2100 g, while
C.
sordidus
ranged between 16 and 33.5 cm in total
length and between 60 and 710 g in weight.
The estimated length - weight equations for the
investigated species (Figure 6) are:
H. harid
: W= 0.0182 L
2.9323
C. sordidus
: W= 0.0182 L
3.0169
The b-value not significantly different from 3, so
those species are grown isometrically.
Figure 5 Growth in length and growth increment of
Hipposcarus harid
and
Chlorurs sordidus
The weights corresponding to various age groups for
the two investigated species were calculated by
applying the corresponding length weight relationship
to the estimated lengths. The growth rate in weight
was much slower during the first year of life
increasing to reach its maximum at the end of the fifth
year of life for
H.harid
and the third year of life for
C.
sordidus
then decreasing with further increasing in age
(Figure 7).
2.4 Growth parameters
The estimated von Bertalanffy growth parameters (L∞,
K and t
o
) were as follows:
H. harid
For growth in length: L
t
= 57.16 (1 - e
-0.23 (t +0.69)
)
For growth in weight: Wt = 2585 (1 - e
-0.23 (t +0.69)
)
2.9323
C. sordidus
For growth in length: L
t
= 40.27 (1 - e
-0.28 (t +0.17)
)
For growth in weight: Wt = 1265 (1 - e
-0.28 (t +0.17)
)
3.0169