For the purposes of the State of the Catchment 2008 reports, an index of threatened species condition, or recovery was calculated for each Catchment Management Authority region as the mean of sustainability scores for all threatened species that were able to be assessed. However, given that sustainability scores were available for very few species in each region, the index is inadequate without an increase in the number of threatened species being monitored. Although scores for individual species are categorical rather than continuous, the change in the mean over time may reflect net changes in the sustainability of individual species over time.