Stocks Discrimination in Lady Fish, Elops machnata (Forskal, 1775) from Southeast and Southwest Coast of India Based on Morphometric and Meristic Analysis

Muthusamy THANGARAJ,Ramachandran KUMARAN,Shanmugam CHANDRASEKAR

doi:10.15835/nsb10110225

Muthusamy THANGARAJ, Ramachandran KUMARAN + Show 1 more

Open Access

https://doi.org/10.15835/nsb10110225

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Abstract

Morphometric and meristic analysis of ladyfish, Elops machnata, were used to discriminate stocks along the Southeast and Southwest coast estuaries of India. Morphometric and meristic analyses showed a similar pattern of differentiation between E. machnata stocks and revealed a clear discreteness of two groups, an East coast (Marakanam, Parangipettai and Muthupettai) population and a West coast (Cochin) population. Higher total length (TL) (28.00 ± 7.043 cm), fork length (FL) (89.27 ± 2.201% TL) and standard length (SL) (81.77 ± 2.582% TL) were recorded in Cochin population and they were significantly different from the other three populations. Meristic counts were relatively homogenous in all the studied populations. No significant variation was found in counts of dorsal fin ray (DFR), anal fin ray (AFR), pectoral fin ray (PFR) and pelvic fin ray (PLFR). The first and second components (PCA analysis) accounted for about 92.2% of variation in all the morphometric characters. Among them, pre pectoral length (PPL) and pre dorsal length (PDL) showed high loading values in PC1 in all four populations. The overall random assignment of individuals to their original group was higher in morphometric than in meristic analysis. Such a presumption could be authenticated henceforth with molecular markers. Hence, further studies, using molecular markers are still required to precisely evaluate the genetic structure of E. machnata along the Indian coast.

Highlights

Elops machnata belongs to the family Elopidae, which forms part of the order Elopiformes
In terms of conservation status, E. machnata is listed as a species of least concern (LC) in the International Union for Conservation of Nature (IUCN) red list (Adams et al, 2018)
Morphometric analysis has been applied to many stock differentiation and life-history problems in many fish species (Bronte et al, 1999)

Summary

Introduction

Elops machnata belongs to the family Elopidae, which forms part of the order Elopiformes. Elops species are important components of global fisheries, in either commercial, recreational or subsistence sectors (McBride et al, 2010). If there is any morphological variation in various populations of a particular species, one can discriminate the morphotypes, and such variation may be useful in assessing the stock structure of populations (Joseph and Jayasankar, 2001). Those morphological differences within a morphotype may indicate geographically isolated stocks, whose shapes may be influenced based on local environmental conditions or by genetic bases (Joseph and Jayasankar, 2001)

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