SPATIAL STRUCTURING OF FISH COMMUNITY ALONG THE VAMANAPURAM RIVER, SOUTH KERALA, INDIA
Vamanapuram is a small west flowing river originating from the Chemmingimottai at about +1860 MSL, in Western Ghats. The drainage of the river is 687 km2 and the length is 88 km. The river flows through all terrains from high to lowlands. Twenty two sites were chosen for sampling throughout the Vamanapuram River from headwaters to mouth of the river. Among the 22sites, 6 were hill streams, 10 were lowland streams, 4 were rivers and 2 were of estuarine character. The fishes were sampled with monofilament gill nets of various mesh size ranging from 6mm to 100 mm. The fishing effort was kept uniform in all the study sites by operating the nets for 20 minutes. The fishes were identified and the species wise number of specimens was counted. A total of 31 fish species were collected and identified. The species wise distribution of fish along the four habitats is given below.
Lowland stream has the highest number of fish species and Puntius amphibius was the dominating species. Along the stream habitat, Devario aequipinnatus was dominating and Dawkinsia filamentosa was the dominating species in the river habitat. Along the estuarine habitat, Ambassis gymnocepahlus was the dominating species. Puntius amphibius and Glossogobius giuris were presented in all the four habitats. Ninteen species have been represented in the freshwater region and 16 species in the estuarine region. Cyprinids dominated the freshwater habitats and Perciform fishes dominated the estuarine region. The structuring of fish community based on the stomach contents and morphological characters is discussed in detail. The spatial distribution of fish species is discussed in the light of the physical characteristics of the habitats.
