Two separate indicators of fish community health are measured to provide a condition score:
- Native species richness (number of native fish species in a sample); and
- Abundance of pest fish (proportion of a sample that is pest fish)
Fish are sampled by electrofishing. To derive a fish score, samples from the 2015/16 year were compared to what is ‘expected’ in a minimally disturbed reference stream with similar landscape attributes. ‘Expected’ fish are modelled from fish sampling data provided by Catchment Solutions, Reef Catchments, and the Department of Science, Information Technology and Innovation.
Currently, the types of species (composition) that are observed during the sampling are not considered when determining a condition score. More work will be undertaken in the future to improve the ‘expected’ model and examine how fish community health can incorporate species composition in the overall score.