Abstract:
The present study was undertaken to get information on the maximum size, age
and growth parameters and mortality of Gerres filamentosus. The length frequency data
were grouped sex wise into 1 cm class intervals, sequentially arranged for two years and
used for estimation of growth and mortality. L∞ and K values were obtained by electronic
length frequency analysis of computer based method. Value of ‘t0’ (age at ‘0’ length) was
estimated by substituting the L∞ and K in the Pauly’s empirical equation. Natural mortality
was estimated using Pauly’s method. Fishing mortality rate (F) was calculated from the F
= Z – M relationship. The asymptotic length (L∞) and growth coefficient (K) were found
to be 26.9 cm and 1.45•year-1
, respectively in males, and 27.11 cm and 1.50•year-1 in
females. The ‘t0’ values estimated by substituting the L∞ and K in Pauly’s equation were -
0.1109 in males and -0.1073 in females. Instantaneous rates of mortality (Z) estimated by
length converted catch curve for male and female were 3.14 and 3.27. Natural mortality
(M) estimated by Pauly’s empirical equation for male and female were 2.41 and 2.47 and
the estimated fishing mortality for male and female were 0.73 and 0.80, respectively. The
computed current exploitation ratios (E) were 0.23 and 0.24. It is concluded that because
computed current exploitation rates (E) are lower than the predicted E, the stock is not
overexploited and the fishing pressure on the stock is not excessive. As the G. filamento-sus is exploited under this condition, below the optimum level indicating scope of slight
increase in efforts.
