Distribution and post-glacial dispersal of freshwater fishes in South Westland, New Zealand

Abstract

Sixteen native and two introduced species of fishes were recorded in a survey of South Westland fresh waters. All of the native species are diadromous, except for the brown mudfish (Neochanna apoda), which was recorded only north ofWaiho River. The number of fish species recorded in South Westland was lower than the number known from the Buller River catchment or North Westland, but greater than in western Fiordland. It is suggested that during the Otiran glaciation, freshwater fishes on the west coast of the South Island were restricted to the Buller River catchment and parts of North Westland. Diadromous fishes have recolonised South Westland readily from those northern refugia, but non-diadromous fishes appear to have been reinvading the area more slowly. N. apoda has adaptations which have allowed it to recolonise more rapidly than most non-diadromous species.

Keywords:

• freshwater fish
• distribution survey
• zoogeography
• Otira glaciation