Morphometrics Analysis of Tenualosa ilisha, Alosa sapidissima and Tenualosa reevesii

In this study, 107 samples of Tenualosa ilisha, Alosa sapidissima and T. reevesii were dissected and observed, and the morphological characteristics of T. ilisha were studied in detail. The morphological variations of T. ilisha and A. sapidissima and T. reevesii were analyzed using traditional morphometrics. In cluster analysis of 7 measurable parameters ratio, the T. ilisha and T. reevesii populations were clustered and then clustered with A. sapidissima. This was in confirmation with their classification status. In appearance, the short anal fin covered with squama of T. ilisha was different from that of A. sapidissima and T. reevesii. The number of columns scale, body length/body height and body length/head length of A. sapidissima were bigger than those of the other two Tenualosa species, so the A. sapidissima had a slenderer somatotype and smaller head. As for meristic characters, the first gill raker and vertebra were different from each other in these three species. The number of the first gill raker T. ilisha, T. reevesii and A. sapidissima were 181-219+153-224, 95-131+170-175 and 24-31+47-55 respectively. The number of the first gill raker T. ilisha, T. reevesii and A. sapidissima were 46-48, 37-39 and 55-57 respectively. As for internal structure, these three species could be clearly identified based on the shape of stomach, the size of blind sac, the length and the number of pyloric caecum, the bending number and relative length of intestine. At the same time, the different structures of digestive tract of the T. ilisha, A. sapidissima and T. reevesii indicated that the diets had been differentiated.