HABITAT REQUIREMENTS OF BLACK-MUDFISH (NEOCHANNA-DIVERSUS) IN THE WAIKATO REGION, NORTH-ISLAND, NEW-ZEALAND

Black mudfish (Neochanna diversus) were found at 39 of 80 sites in the Waikato region, New Zealand, ranging from large wetlands to small swa mpy streams. Of the sites with mudfish, 87% were dry at some time duri ng summer. Sites with mudfish also generally had emergent and overhang ing vegetation and tree roots, and showed low to moderate human impact . Black mudfish coexisted at some sites with juvenile eels or mosquito fish, but were absent from all sites with common bullies (Gobiomorphus cotidianus) or inanga (Galaxias maculatus). Sites with mudfish had al most exclusively semi-mineralised substrates or peat; only one site ha d mineralised substrate. Geometric mean catch rate for the 39 sites wi th mudfish was 0.70 fish per trap per night. Mean summer water depth w as only 2.1 cm at sites with mudfish, compared to 22.6 cm at 41 sites without. Winter and maximum water depths were also less at sites with mudfish than at sites without mudfish. Mean turbidity was 11.5 nephelo metric turbidity units (NTU) at sites with mudfish, but 21.3 NTU at si tes without mudfish. Mudfish catch rates were negatively correlated wi th summer water depth, winter water depth, disturbance scale rating, a nd turbidity. A discriminant function model based on these variables s uccessfully predicted 95% of the sites with mudfish. Habitat preferenc e curves are also presented.