31 3 Fish distribution, status and threats in the rivers and springs of the Queensland Lake Eyre Basin Adam Kerezsy Introduction Even a cursory glance at a map of central Australian waterways tells the story: there aren’t many, and there are really only three big rivers (Fig. 3.1). The Cooper, the Diamantina and the Georgina Rivers are the collective engine-room of Australian arid-zone aquatic ecosystems, and run-off from unpredictable monsoon rains is their fuel. The study of fish ecology in the Lake Eyre Basin is patchy. Despite the fact that most permanent waters are within Queensland (Silcock 2009), both the earliest fish surveys (Glover and Sim 1978 Glover 1979) and ecological studies (Puckridge 1999) were in South Australia. Sites from the upper and mid-reaches of the three big rivers in Queensland have only been sampled since 2000 (Bailey and Long 2001 Costelloe et al. 2004), with the Cooper consistently receiving most attention (Arthington et al. 2005 Balcombe et al. 2007 Balcombe and Arthington 2009). Long-term repeated sampling of multiple riverine sites throughout all three major rivers of the Queensland Lake Eyre Basin occurred between 2006 and 2010 (Fig. 3.1 Kerezsy 2010 Kerezsy 2011) and then from 2010 onwards through the implementation of the Lake Eyre Basin Rivers Assessment, administered by a combination of natural resource agencies based in Queensland, South Australia and the Northern Territory. No fish species present in the rivers of the Queensland Lake Eyre Basin is currently listed under either state or federal endangered species legislation, and none is a species on the international Red List of Threatened Species (International Union for the Conservation of Nature 2016). Though far smaller in area, the Great Artesian Basin spring complexes in Queensland – the Barcaldine group in the north-east, the centrally located Springvale group and the Mulligan group on the eastern edge of the Simpson Desert – have received comparatively more attention over a longer time than the riverine environments (Fig. 3.1). This disparity has been due largely to the notable numbers of endemic plants, invertebrates and fish within these springs (Ponder and Clark 1990 Fairfax et al. 2007 Fensham et al. 2011 Kerezsy and Fensham 2013). Spring complexes – or groups – are characterised by multiple shallow, groundwater-fed ponded and/or damp areas. All are associated with faulting, and it is the presence of faults that has enabled water from the Great Artesian Basin to reach the surface over a prolonged period. Most native fish species present in Great Artesian Basin spring complexes in Queensland are listed as vulnerable, endangered or critically endangered under relevant Australian legislation (Nature Conservation Act 1992 Environment Protection and