Bridging knowledge gaps for the conservation and management of a ‘Data Deficient’, diadromous fish: the Indo-Pacific tarpon, Megalops cyprinoides

Abstract

Context The Indo-Pacific tarpon (Megalops cyprinoides) is a diadromous species, for which limited information is available regarding demographics and exploitation levels. Aim We aimed to fill critical knowledge gaps on population dynamics and exploitation levels of M. cyprinoides along the south-western coast of India. Methods Structured length frequency-based population dynamics models were used to determine the growth, mortality and exploitation levels of the species. Key results Habitat-related variations in growth patterns were found, with positive allometric growth in the marine (b = 3.208), and negative allometric growth in freshwater (2.759) and estuarine (2.876) habitats. Different estimates of natural mortality suggested high fishing pressure, potentially threatening the long-term sustainability of local M. cyprinoides populations. Conclusions This study provides the first comprehensive estimates of demographic parameters of M. cyprinoides, and contributes significantly to our knowledge required for the management of Indo-Pacific tarpon fisheries. The critical need to address overfishing and habitat degradation to ensure long-term sustainability of local populations is highlighted. Implications Knowledge generated through this study will help inform improved conservation assessments of this ‘Data Deficient’ species, in addition to informing the development and implementation of conservation and management plans.