Journal of the Marine Biological Association of India

Population dynamics of Bentfin devil ray, Mobula thurstoni (Lloyd, 1908), from Lakshadweep Sea, south-west coast of India

Volume 65 Issue 2

K. S. Swathy, S. M. Raffi, Bincy M. Raj, T. M. Sreenath, S. Athul and Geethu Mohan

10.6024/jmbai.2023.65.2.2405-08

Abstract

A demographic study was carried out on Mobula thurstoni covering 654 specimens’ commercial fisheries along the Arabian Sea coast of southwestern India from January 2019 to December 2019. Overall sex ratio (M: F) did not deviate significantly from 1:1; females predominated the catches in almost all months. The asymptotic length (L∞) and growth constant (K) were 204.23 cm and 0.34 year-1 respectively. The growth performance index (Ø) was estimated to be 4.152. The total instantaneous mortality rate (Z), natural mortality (M) and fishing mortality (F) were observed to be 0.98 year-1, 0.51 year-1 and 0.47 year-1 respectively. The exploitation rate (E) (0.43) was close to the observed E max of 0.545 indicating the high harvest pressure on these species. Urgent management measures are required to ensure the sustainability of M. thurstoni fishery from Lakshadweep Sea, southwest Coast India.

Keywords

Mobula thurstoni, length-weight relationship, sex ratio, growth parameters, mortality parameters, exploitation

Date : 20-11-2023