| Abstract: | Habitat fragmentation edge effects on riverine fish could have implications for stream fish populations and their management. We examined effects of forest fragmentation on banded kokopu and longfin eels in New Zealand. Banded kokopu prefer small shaded streams with bouldery substrates and instream cover, whereas longfin eels are found in a variety of habitats. We hypothesized that the densities of banded kokopu would be higher in forested than grassland streams, and the densities would be lower around forest margins. We sampled pools in streams flowing from native podocarp/broad-leaf forests into grassland using Gee–Minnow traps. Pools were sampled longitudinally on each stream from >50 m into the forest to >50 m downstream from the forest margin in open grassland. Banded kokopu densities were higher in interior habitat ?50 m into forests than in grassland streams. Fish caught in grassland pools were smaller than in forested pools. Longfin eels were caught in all streams, but numbers and sizes were similar in habitats; thus not likely to generate the pattern observed for banded kokopu. We found that terrestrial habitat fragmentation can impact stream fish populations by decreasing their occupancy of habitats in the vicinity of the boundary between different terrestrial habitats. |
