Spawning site selection, egg development, and larval drift of Galaxias postvectis and G. fasciatus in a New Zealand stream

Abstract

Twelve Galaxias postvectis (shortjaw kokopu) and four G. fasciatus (banded kokopu) spawning sites were found on the margins of the Katikara Stream, Taranaki, New Zealand. This is the first time G. postvectis spawning sites have been documented. G. fasciatus spawning sites discovered in this study confirm previous observations elsewhere in New Zealand. These spawning sites were all found out of water, variable distances from the base flow water level amongst stony substrate, vegetation, and debris. Most G. fasciatus appeared to lay their eggs, and subsequently hatch, c. 3 weeks earlier than G. postvectis, which spawned from 9 to 17 May 2001. G. brevipinnis (koaro) larvae were also identified drifting downstream in late May and mid June 2001. Deposition of eggs and subsequent hatching were found to be associated with elevated flows.

Keywords:

• drifting larvae
• eggs
• flood flows
• Galaxias
• riparian zone
• spawning
• terrestrial spawning site