Length-weight, length-length relationships and condition factor of obtuse barracuda Sphyraena obtusata Cuvier, 1829 (Pisces: Perciformes) from Vizhinjam coast, Kerala, India

Abstract

Eleven morphometric variables including weight were recorded for 429 specimens of obtuse barracuda Sphyraena obtusata Cuvier, 1829 collected over a period of two years from January 2017 to December 2018, from Vizhinjam fish landing centre, Thiruvananthapuram, Kerala. Length-weight relationship and length-length relationship of the species were estimated using linear regression analysis. Different length measurements were converted to ratios with standard length as morphometric ratios and the growth rate was assessed gender wise. Length-weight relationship for male and female population were estimated as W_m= 13.326 × L^3.2409 and W_f = 11.952 × L^2.9821, respectively. Linear relationships for other morphometric variables and morphometric ratios with standard length were established for the species. Principal component analysis was performed and total length, snout length and snout to pre-nostril length were identified as key morphometric variables discriminating gender. The relative condition factor was estimated as 1.04+0.13 for total population and the role of morphometric ratios in sex differentiation was examined.

 Keywords: Condition factor, Morphometric ratio, Morphometric sex difference, Principal component analysis, Sphyraena obtusata