There are two species of the Retropinnidae family found in New Zealand – the common smelt (Retropinna retropinna) and Stokells smelt (Stokellia anisodon). Stokells smelt are only found on the east coast of the South Island, around the river mouths and estuaries of the big braided rivers.
Smelt are a shoaling species, which means they swim in schools near the water surface rather than resting or hiding on the substrate. They are often seen out in the open in streams and lakes as they feed on drifting food organisms.
The common smelt is widespread throughout New Zealand. It lives in flowing and still water, and there are both diadromous and non-diadromous populations here.
Although they are not a climbing species, smelt are good swimmers and will penetrate well inland in river systems that are not too steep.
Smelt are very sensitive to pollutants like ammonia and stressors like high water temperature. Smelt are therefore an appropriate native species for establishing guidelines for New Zealand waterways, and usually their presence indicates that the water quality is suitable for most other fish.
In rivers, juveniles are often captured by whitebaiters as they migrate upstream and mix with the whitebait (galaxiids). In the Waikato catchment, they are referred to as “number two whitebait” and are actively fished for.
Acknowledgement: Department of Conservation Te Papa Atawhai, Creative Commons 4.0