The community structure, density, and biomass of native fish species was determined for first-to second-order streams draining mature pine, native forest, and pasture catchments in seven, North Island, New Zealand, east coast rivers or streams. Multiple-pass electric fishing was used to determine fish densities, and differences in fish community structure between land uses were detected using nonmetric multi-dimensional scaling analysis. Species responsible for changes in fish community structure were identified by comparing species densities between land uses. Six fish species occurred commonly within each drainage system and although there was no difference in fish community structure between streams in native or exotic forest, differences 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 pasture supported an increased fish density and biomass due mainly to increases in shortfinned eels. There were fewer banded kokopu in pasture than in forested streams, Received 15 December 1997; accepted 13 October 1998 but exotic forest streams contained as many banded kokopu as native forest streams. M97069

SynopsisDie1 and spatial differences in distribution were determined for the larvae, juveniles, and adults of Galaxias grucilis (Galaxiidae) in a New Zealand dune lake during summer months. Larvae (mostly 10-25 mm TL) and juveniles (25-40 mm TL) inhabited shallow (O-3 m) waters of the limnetic zone and fed predominantly on two limnetic zooplankton species; Bosmina meridionalis and a calanoid copepod. At about 40 mm TL, fish moved from the limnetic to the littoral zone and expanded dietary breadth from two to over seven main prey species, including five species of littoral invertebrates. After reaching a size of about 60 mm TL, most fish moved back offshore to the deeper waters (5-15 m) of the limnetic zone during the day, moving back to the littoral zone at night to feed on invertebrates. The selection of different intra-lacustrine habitats by the various size groups of G. gracilis, and the movements between them, are interpreted as adaptive responses to the interaction between ontogenetic changes in feeding requirements and predation risk.

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