30 – Recovery of the red-finned blue-eye^381estimates is swamped by variation in abundance due to seasonal and stochastic
variation. Nonetheless, effort has been made to categorise total abundance in each
spring (e.g. <10, 11–100, 100–1000, >1000 individuals) in order to track trends. Very
small populations (<10 individuals) can be difficult to detect; therefore, zero
detections over successive monitoring periods roughly equating to 1 year were
required before a local population was deemed extinct (Fig. 30.3).
Figure 30.3 shows the results of Bush Heritage’s red-finned blue-eye
monitoring from 2009 to 2016. The 2009 audit revealed the species to be present in
only four springs. Two of these naturally occurring populations (NW90s and
Fig. 30.2. North-west and central spring complex at Edgbaston Reserve showing location of springs
mentioned in the text.