Abstract:
The population dynamics of Gerres abbreviatus from the
Parangipettai waters, Southeast coast of India was investigated based on
length frequency data, using FiSAT software. Growth parameters of G.
abbreviatus were estimated using ELEFAN I method. The theoretical ages at
length zero (t0) were estimated by substituting the asymptotic length (L∞) and
growth coefficient (K) in Pauly’s equation. The fitted von Bertalnaffy’s
growth equations for male and femaleG. abbreviatus were Lt=27.8 [1 – exp
{-1.30(t+0.1236)}] and Lt=28.2 [1-exp {-1.36 (t+ 0.1175)}] where L∞ values
are in cm, K values are on annual basis and t0 values are in years. The
estimated growth performance index (Ø) for male and female G. abbreviatus
were 3.002 and 3.034 respectively while the estimated life spans of male and
female G. abbreviatus were 2.18 and 2.08 years. Instantaneous rates of total
mortality (Z) estimated by length converted catch curve for male and female
G. abbreviatus were 3.06 and 2.99 yr-1 respectively. Natural mortality (M)
estimated by Pauly’s empirical equation for male and female G. abbreviatus
were 2.24 and 2.29 yr-1 and the estimated fishing mortality for male and
female G. abbreviatus were 0.82 and 0.70 yr-1 respectively. Relative yield per
recruit analysis incorporating probabilities of capture indicates that G.
abbreviatus in the Parangipettai waters is exploited below the optimum level
indicating scope for increase in fishing efforts without leading to
overexploitation.
