Length–weight relationships (LWR) have important implications in fisheries science and population dynamics (Erzini, 1994). Size of the fish is generally relevant than age, mainly because several ecological and physiological factors are more size dependent than age dependent (Santos et al., 2002). It is useful in fishery assessments for predicting weights from the more easily measured lengths, because direct weight measurements can take more time in the field yield assessment and biomass calculation (Ricker, 1975; Petrakis and Stergiou, 1995; Martin-Smith, 1996; Garcia et al., 1998; Sinovcic et al., 2004; Froese, 2006). Knowledge of the relationship between length and weight of a fish species in a given geographic region is useful for three reasons: (a) estimation of weight-at-age from total reported catch weight and length-frequency distributions; (b) a practical index of the condition of fish; (c) comparisons of life history between-regions (Petrakis and Stergiou, 1995).

and its logarithmic form: log W = log a + b log L as followed by Ramasesaiah and Murty (1997). Where W is the total weight, L is the total length, “a” is the intercept, and “b” is the slope. Length-weight relationships may help determine whether somatic growth is isometric (b=3) or allometric (negative if b<3 or positive if b>3) (Ricker, 1973; Spiegel, 1991). The degree of association between the variables was computed by the determination of the regression coefficient (r²) and statistical significance level of r² and 95% confidence limits of parameters a and b were estimated (Santos et al., 2002).

Figure 1 Study area map showing the location where collection was made

The exponent b of length-weight relationships ranged between 2.71 for Scatophagus argus and 3.20 for Upeneus vittatus. The LWR were significant (p<0.05) for these coral reef associated species. In terms of growth type, the results revealed that seven species had negative allometric (b<3), one species had isometric (b=3) and two species had positive allometric (b>3) growth.

Table 1 Statistical description and LWR parameters obtained for 10 coral reef associated fishes length parameters (length ranges in cm (minimum and maximum), mean and standard deviation (SD)), weight parameters (weight ranges (minimum and maximum), mean and standard deviation (SD)), parameters of the LWR (N: number of specimens sampled, a: intercept, b: slope and r2 coefficient of determination) and type of growth (isometric (I) or allometric (A), (positive or negative))

3 Discussion

Vasantharajan M., Jawahar P., Sundaramoorthy B., and Venkatasamy M., 2014, Length - weight relationship ofLethrinus lentjan (lacepede, 1802)and Lethrinus nebulosus (forsskal, 1775) exploited in Thoothukudi coast, Tamil Nadu, India, Indian Journal of Vetinary and Animal Science Research, 43 (1): 14-18