The Effect of Seasonal Changes on Freshwater Fish Assemblages and Environmental Factors in Bukit Merah Reservoir (Malaysia)

Seasonal changes of freshwater fish assemblages and environmental factors in Bukit Merah Reservoir were carried out from January-February 2013 (dry season) to March-April 2013 (wet season) by measuring several physico-chemical parameters such as dissolved oxygen (DO), water temperature, pH, water conductivity, total dissolved solids (TDS) and water clarity. 19 fish species comprising of 10 families were collected by using experimental gill nets with different mesh sizes at four different sampling stations. Mean CPUE for total catch and biomass were significantly different between dry and wet season (p < 0.05). Based on a T-test analysis, water temperature, pH and conductivity were significantly different (p < 0.05) between seasons whereas a one-way ANOVA displayed a significant difference in TDS and water clarity between sampling stations (p < 0.05), implicating that those factors did not give major influence towards other parameters in a man-made reservoir. From all fish species studied, only mean CPUE for individuals (CPUEn) of Osteochilus vittatus and Oxygaster anomalura had a significant difference between seasons (p < 0.05); probably an indicator of their migration season