[Influence on the spatial distribution of fish in Taizi River basin by environmental factors at multiple scales]

The deterioration of fish is influenced by various types of environmental factors. To develop protection plans that are more suitable, non-metric multidimensional scaling analysis (NMS) was used to investigate the influence of environmental factors at multiple scales on the spatial distribution of fish. The results of cluster analysis showed that there were three types of spatial distribution of fish, i.e. upstream timber and tributary headstream area, midstream hilly area, and downstream plain area. Results of NMS analysis indicated the significant correlations between spatial distribution of fish and environmental factors at multiple scales. Altitude, stream order and land use were three important factors influencing the fish distribution at the watershed scale. Combination of velocity and depth, habitat inhomogeneity and electrical conductivity significantly affected fish distribution at the reach scale, whereas the quality of bottom material showed significant influence at the microhabitat scale. Therefore, the effect of specific environmental factors at multiple scales should be taken into consideration in the basin fish conversation management.