Effects of land use on native fish communities in east coast streams of the North Island of New Zealand

The community structure, density, and biomass of native fish species was de termined for first- to second-order streams draining mature pine, native fo rest, and pasture catchments in seven, North Island, New Zealand, east coas t rivers or streams. Multiple-pass electric fishing was used to determine f ish densities, and differences in fish community structure between land use s were detected using nonmetric multi-dimensional scaling analysis. Species responsible for changes in fish community structure were identified by com paring species densities between land uses. Six fish species occurred commo nly within each drainage system and although there was no difference in fis h community structure between streams in native or exotic forest, differenc es occurred between the fish communities of forested and pastoral streams. Pastoral streams contained more shortfinned eels (Anguilla australis), more inanga (Galaxias maculatus), and fewer banded kokopu (Galaxias fasciatus) than forested streams. Fish biomass was also higher in pastoral streams. We concluded that the type of forest (mature exotic pine versus mixed-species indigenous) had little effect on the native fish populations, but that pas ture supported an increased fish density and biomass due mainly to increase s in shortfinned eels. There were fewer banded kokopu in pasture than in fo rested streams, but exotic forest streams contained as many banded kokopu a s native forest streams.