Distribution and conservation status of the dwarf inanga Galaxias gracilis (Teleostei: Galaxiidae) an endemic fish of Northland dune lakes

Surveys of 27 Northland lakes revealed two new locations for Galaxias gracilis but confirmed its restricted geographical distribution. It is now present in 11 lakes on the west coast of the North Island within 50 km of Dargaville, and in Lake Ototoa on the South Kaipara Head, where it was introduced in 1986. Densities of G. gracilis were determined by nocturnal fyke netting in the littoral zone of the North Kaipara lakes. It was abundant in two of these lakes, common in two, rare in five, and extinct or close to it in at least three others. We conclude that G. gracilis has one of the most restricted geographical distributions of any New Zealand native fish, and that its densities have declined in over 80% of the lakes from which it has been recorded. Although trout predation could account for the current low density of G. gracilis in three lakes, it is not responsible for low densities in six others. Factors responsible for the decline of this species are therefore unknown, so it is a threatened species in terms of its conservation status.

Keywords:

• Galaxias gracilis
• threatened fish
• Northland lakes
• fish surveys
• Galaxiidae
• trout predation

Notes

NIWA, National Institute of Water and Atmospheric Research Ltd, P.O. Box 11 115, Hamilton, New Zealand