LENGTH-WEIGHT RELATIONSHIP AND RELATIVE CONDITION FACTOR OF A MIGRATORY AND A RESIDENT HILL STREAM FISH FROM HYDROPOWER-IMPACTED TRIBUTARIES OF PUNATSANGCHHU RIVER, BHUTAN

Abstract

This study aimed to determine the length-weight relationship (LWR) and access the relative condition factor (K_n) of migratory fish, Schizothorax richardsonii and resident fish, Garra gotyla from the tributaries of Punatsangchhu River within the vicinity of the hydropower development area. The sampled tributaries were categorized into three zones: upstream, fragmented or impacted zone and downstream zone. Both species indicated significant negative allometric growth. The allometric form of LWR for S. richardsonii and G. gotyla is established as W = 0.0155L^2.6806 and W = 0.0161L^2.7506, respectively. The K_n of both species were > 1 at the downstream zone only. One-way ANOVA and Tukey HSD test indicated significantly lower K_n in the fragmented zone and upstream zone as compared to the downstream zone for S. richardsonii. An unpaired two-sample t-test indicated insignificant differences in K_n of G. gotyla between the downstream and fragmented zone. This study reflects the greater impacts of hydropower development on fragmented zone and migratory fish as compared to resident fish. The present study will help in the improvement of long-term monitoring of the impacts of hydropower development on fisheries and standardization of fisheries monitoring programs in Bhutan.