International Journal of Aquaculture, 2017, Vol.7, No.24, 159-165
160
2 Materials and Methods
The length frequency data, catch and effort data have been collected from Tuticorin coast of Gulf of Mannar from
January 2004 to December 2004.
S. gibbus
the catch and effort data have been assessing for the estimation growth
parameters by ELEFAN Programme (Gayanilo et.al., 1995), mortality, exploitation rates and recruitment pattern
by using FiSAT programme (Gyanilo and Pauly, 1997). ‘L∞’ and ‘K’ was calculated by Ford-Walford plot (Ford,
1933; Walford, 1946) of Lt against Lt + 1 on mortality basis and ‘t
0
’ was calculated by Gulland and Holt’s (1959)
plot. The growth was expressed using von Bertalanffy’s (1938) equation given as
Where L∞ is the asymptotic length ‘K’ Growth coefficient
3 Results and Discussion
Scarus gibbus
, the wide range of variety of length group of fishes are characterized by proliferate of growth
(depends upon tropical or temperate continent), age-at-first maturity spawning capability, in which are
characteristic of r and k theory of perciform the selected species. The conservation of scarid species, off Tuticorin
coast of India, is to avoid overfishing in this geographical zone.
3.1 Growth parameters
Figure 1 shows restructured length distribution for the computed growth curve. The von Bertalanffy growth
equation for
S. gibbus
was estimated as L∞ = 104.50 and K = 0.23. Choat and Axe (1996) has been revealed that
the bumphead parrotfish (
Bolbometopon muricatum
) to attain to the maximum reach at 1000 mm at Solomon
Islands (Hamilton, 2004).
S. gibbus
is relatively moderate in growth K = 0.23. According to Sparre and Venema
(1993) has suggested that the same genus group and related the species level was K and natural mortality, and it is
related to same age and the length and weight of the fish. The M value was calculated 0.47 and the M/K ratio of
S.
gibbus
was estimated 2.04. The M/K value is found to be in close proximity limit among the closely associated
species (Beverton and Holt, 1956). The M/K ration,
S. gibbus
have been decreasing within the range of 2.0-3.0.
Genus
Scaridae
, the species level was closely associated group, the result shows that the similar K and L∞ values
have life-span varying by a factor of 2-4,
Chlorurus microrhinos
(K = 0.307, L∞ = 428, T
max
= 15),
Chlorurus
sordidus
(K = 1.117, L∞ = 193, T
max
= 9),
Hipposcarus longiceps
(K = 0.282, L∞ = 350, T
max
= 12),
Bolbometpon
muricatum
(K = 0.136, L∞ = 693.81, t
0
= -0.11),
Cetoscarus bicolor
(K = 0.255, L∞ = 420.56, t
0
= -0.09),
Chlorurus microrhinos
(K = 0.301, L∞ = 429.89, t
0
= -0.08),
Scarus frenatus
(K = 0.844, L∞ = 232.36, t
0
= -0.05),
Scarus niger
(K = 0.736, L∞ = 238.01, t
0
= -0.06),
Scarus psitticus
(K = 1.190, L∞ = 172.10, t
0
= -0.05),
Scarus
rivulatus
(K = 0.220, L∞ = 308.50, t
0
= -0.15),
Scarus schlegeli
(K = 0.403, L∞ = 238.81, t
0
= -0.11),
Sparisoma
atomrium
(K = 1.828, L∞ = 101.08, t
0
= -0.06),
Sparisoma aurofrenatum
(K = 1.163, L∞ = 170.89, t
0
= -0.05),
Sparisoma chrysopterum
(K = 1.176, L∞ = 237.97, t
0
= -0.04),
Sparisoma rubripinne
(K = 0.811, L∞ =237.57, t
0
= -0.05) and
Sparisoma viride
(K = 0.498, L∞ = 318.96, t
0
= -0.06) (Choat and Robertson, 2002).
Figure 1 Estimation of growth parameter through ELEFAN I programme of
Scarus gibbus
