Effect of land use on the distribution and abundance of native fish in tributaries of the Waikato River in the Hakarimata Range, North Island, New Zealand

Abstract

The effect of land use on fish community structure was examined at fifty‐five sites in tributaries draining exotic, indigenous forest and pastoral catchments in the Hakarimata range in March and April 1987. Using a model containing percentage woody debris, temperature, and substrate coarseness, 76% of the sites were classified into correct land uses by discriminant analysis. This indicated that differences in stream habitat, and hence of the fish fauna, were related to effects of changed land use rather than other confounding physical or geographical features of the streams in the catchments. Tributaries in indigenous forest were numerically dominated by banded kokopu (Galaxias fasciatus) and longfinned eel (Anguilla dieffenbachii) , with redfinned bully (Gobiomorphus huttoni) and giant kokopu ( G . argenteus) occasionally being caught. Pastoral streams below the forest generally supported higher densities and contained more species including the forested species above, Cran's bully (G. basalis) , and shortfinned eel ( A . australis ). As the amount of indigenous forest in the catchment decreased the fauna became less abundant and less diverse and was dominated by both species of eel and Cran's bully.