VARIATION OF HILSA SHAD, Tenualosa ilisha IN BANGLADESH INFERRED FROM GEOMETRIC MORPHOMETRIC AND BIOCHEMICAL ANALYSIS

Abstract

Hilsa shad, Tenualosa ilisha is a species of the Family Clupeidae locally known as ilish in Bangladesh. This study investigated the variation among the Hilsa of four wild populations through landmark-based geometric morphometrics and analysis of biochemical composition. To cover the broader zone of the Hilsa availability in Bangladesh, a total of 100 samples of Hilsa 15 females and 10 male of each population were collected from four rivers, The Padma, Meghna, Rupsa and Karnaphuli. After collection, image of each sample were taken for geometric morphometric analyses and muscle tissues were used for biochemical composition analysis. Sixteen landmarks points on the fish’s body were digitized using TPS series software and analyses by using PAST software (version 3.0). The overall body shape variations were found in principal component one (PC1: 75.52%) among four populations indicates that there was significant body shape variation of T. ilisha. The results of scatter plot and UPGMA cluster analysis showed that there were overlapping between Barisal and Khulna populations and some were Chittagong and Khulna populations, but Barisal and Pabna population were distinctly separated. The biochemical composition of crude protein, lipid and Ash contents were carried out following the methods of AOAC (1980). The highest protein contents were found in Barisal populations (15.27%) and lipid contents were found in Khulna population (16.43%) and Ash content was found in Chittagong population (0.98%). The findings of biochemical composition of Hilsa showed significant variation. These body shape variation and biochemical composition differentiation may be related to geographically isolated regions or habitat or feeding habits or other environmental conditions. This result will be helpful for the proper Hilsa stock management as well as for the consumers, fish processors and the researchers. For clear differentiation among populations, more stocks and individuals of each stock are needed to investigate through morphometric and molecular markers analyses.