Effect of River Flow Variability on Spawning Migration of Labeobarbus Species In Infranz River, Lake Tana Sub-basin, Ethiopia

Abstract

The study was conducted in 2011 at four sites of Infranz River selected based on the nature, velocity of the flowing river, human interference and, suitability for fish spawning. Fish samples were collected using gill nets of 6, 8, 10 and 14 cm and monofilament having 5-55 mm mesh size. The potential Evapotranspiration of the river was estimated using the Thornthwaite method. Flow rate of the river was simulated from precipitation data using a 3- parameter monthly water balance model. The CV value for the mean monthly flow (CV= 0.96) was much larger than that of the annual flow (CV=0.19). The river showed an overall decreasing trend of flow rate. The number of adult fishes captured in the river was directly related to the flow. The number of Juveniles was less during the high flow seasons. The number of male and female was positively correlated with flow rate of the river. The decreased in river flow rate have an effect on migratory species; hence, management activities should be practiced in the catchment area of the river so as to increase its flow rate.