Journal of the Marine Biological Association of India

Morphometric characteristics of the Indian ringed skate, Orbiraja powelli (Alcock, 1898), from the Southwest coast of India

Volume 65 Issue 1

A. John Chembian, A. Tiburtius and R. John Peter

doi:10.6024/jmbai.2023.65.1.2286-09

Abstract

Specimens of Orbiraja powelli were collected during May and October’2008 from the southwest coast of India. Males have a total length (TL) of 24.9 cm to 41 cm with a mean value of 35.7 cm, whereas, females TL varied from 27.6 cm to 51.5 cm with a mean value of 44.1 cm. Similarly, males were found to grow in weight at a rate less than cubical (b< 3), whereas, females grew in weight at a rate more than cubical concerning TL and DL (b> 3), resulting in two types of growth, negative allometric for males and positive allometric for females. However, males and females grew in near uniformity until it reaches around 35 cm TL. Since then the growth rate diverges resulting in females becoming relatively heavier than males. This reversal in the growth pattern from juvenile to adult was noticed in other parameters also. Sexually dimorphic relationships were observed between seven morphometric variables, wherein, the variables, disc width, tail length and pre-orbital length were well discriminated between the sexes.

Keywords

Sexual dimorphism, morphometrics, Orbiraja powelli. Arabian Sea, skate

Date : 27-04-2023