New Zealand has five migratory galaxias species – īnanga (Galaxias maculatus), kōaro (Galaxias brevipinnis), banded kōkopu (Galaxias fasciatus), giant kōkopu (Galaxias argenteus) and shortjaw kōkopu (Galaxias postvectis). The juveniles of the five species constitute the New Zealand whitebait fishery. A sixth, non-galaxias species – the common smelt (paraki, Retropinna retropinna) – is also included in the definition of whitebait in the regulations.
The species and the fishery are managed by DOC under several pieces of legislation. Regional councils also play a role in the conservation of these species through managing the adverse effects of resource use on habitat and water quality.
This report summarises current knowledge about migratory galaxiids and the whitebait fishery. Where possible, published literature has been used; where published literature is not available and unpublished reports are accessible these have been cited. Personal communications have also been referenced where unpublished reports or data are not available, but research has been carried out.
Key conclusions of this collation of research and identification of information gaps are:
- The habitat and distribution of all five species are well researched and experts can largely describe their ‘preferred’ adult habitat and also the habitat conditions they tolerate.
- Excluding īnanga, the spawning habitats of the four other species – kōaro, banded kōkopu, giant kōkopu and shortjaw kōkopu – are poorly documented.
- There is very little conclusive research about the effect of harvest on the five species. Some attempts have been made to collect catch data, but these have largely been unsuccessful and/or inaccurate.
- Recent studies have increased knowledge about the catch composition of species nationally, the spawning habitats of two galaxias species and the ecology and biology of īnanga whitebait migrations.
- There is still a limited understanding of the stock structure and life history of the species, with recent studies suggesting these may vary greatly between species and regions.
- Very little information is available on the larval phase of the migratory galaxiids – where they develop (freshwater or marine environments), their swimming ability, diet and the threats and pressures these tiny fish are subject to.
- The pressures on and threats to these species are relatively well known and documented, although the magnitude of each impact on each species is not well understood.
Critical to the conservation and management of these species and the fishery is collating existing information and identifying gaps, so that decision making about future management can be better informed.
Written by Jane Goodman, Freshwater Team, Biodiversity Unit, Department of Conservation, Nelson