title: The Distribution, Recruitment and Movement of Fish in Far Western Queensland
Creators: name: Kerezsy, Adam
Publisher: name: Griffith University
Year: 2010
Subjects: subject: river systems
subject: catchments
subject: anthropogenic disturbance
subject: fish
subject: hydrological histories
subject: western Queensland
subject: golden goby
subject: cod

description: The river systems of far western Queensland, such as the Bulloo in the Bulloo- Bancannia Basin and the Cooper, Diamantina and Georgina in the Lake Eyre Basin, are catchments that have been subjected to minimal anthropogenic disturbance. These rivers are characterised by extreme flow variability by virtue of their geographical locations in the semi-arid and arid areas of central Australia. In general, the fish communities from these areas are poorly known, especially those from the most remote catchments such as the Georgina and its tributaries. The first aim of this study was to more-accurately establish the distributional range of fish species throughout far western Queensland through extended spatial and temporal sampling of all major river systems from the Bulloo west to the Northern Territory border. Fish sampling commenced in September 2006 and continued in December 2006, January 2007, April 2007, August 2007 and November 2007 before concluding in March and April 2008. Extra data from sampling undertaken in November 2008 and as recently as October 2009 has occasionally been included in the thesis chapters where it is relevant to the analysed results or the interpretation and discussion sections. In general, a minimum of three sites was always sampled on each sampling occasion and in each catchment – from east to west the Bulloo, Kyabra, Barcoo, Thomson, Cooper, Diamantina, Georgina and Mulligan. Major flooding occurred in the Georgina and Mulligan catchments in January and February 2007 and in the Barcoo, Thomson and Cooper catchments in January and February 2008. In contrast, neither the Diamantina nor Kyabra catchments experienced overbank flooding for the duration of the study. Consequently, comparison of fish communities between catchments with vastly different hydrological histories became possible using the assembled dataset. The results from the Mulligan catchment are particularly interesting as they provide the first fish records from this watershed and are amongst the few documented instances of fish species migrating long distances in an ephemeral Australian desert river. Seven species were demonstrated to colonise the Mulligan following flooding, and range extensions were also established for golden goby, Glossogobius aureus, in the Diamantina catchment, and the translocated sleepy cod, Oxyeleotris lineolatus, in the Thomson catchment. Biota must possess adaptations or life-cycle traits that enable them to survive in the environments in which they live. Fish from arid-zone rivers that frequently experience total drying and/or extended drying periods live at the realistic limit of freshwater habitation. In the second part of this study, the recruitment patterns of fish species from the Bulloo-Bancannia and Lake Eyre basins in Queensland were investigated using length-frequency analysis of samples from all sampling occasions. In particular, this data was analysed to evaluate whether recruitment is contingent upon flow events or season, or whether fish in isolated arid-zone river systems evince more opportunistic recruitment strategies in order to survive in river systems where channel and flood flows are rare and unpredictable. The results demonstrate that the majority of extant fish species are capable of maintaining their populations in isolated waterholes in the absence of flow events. In river systems where flow is dynamic and stochastic, fish habitat is similarly changeable, for pools and reaches may become inundated only sporadically. Nevertheless, such temporary habitats may be colonised by vagile fish species provided connection with source habitats is established periodically. The current study documents the colonisation of a remote desert river – the Mulligan – by fish from its parent river – the Georgina – following connection during flooding. Additionally, movement patterns are analysed at a smaller scale within the Thomson and Barcoo catchments by examining fish usage of temporarily inundated channels following smaller connection flows. Concepts detailing river function with reference to hydro-ecological models predicated on regular flood flows (Flood Pulse Concept) or connected river channels (River Continuum Concept) are not easily applied to rivers in the Australian arid-zone due to the stochasticity of flow events and the frequency and duration of dry spells. The current study considers the results drawn from the distribution, recruitment and movement studies in relation to existing models describing riverine function, and concludes that a source-sink population model may be useful for describing the dynamics of native fish in central Australia. Under this model, fish recruitment generally occurs along a constant timeframe irrespective of antecedent flows and flooding, whereas movement is highly opportunistic and likely to occur – for some if not all species – whenever migration pathways become available. Given the current lack of information regarding isolated arid-zone rivers in Australia and the unique opportunities they present for both conservation and future study, the final part of this thesis examines the current status of freshwater fish assemblages and species in far western Queensland and the challenges and opportunities that currently exist in both research and management. Although the catchments considered during the study all demonstrate a robust native fish fauna, this is likely to be a result of their isolation and the existence of natural flow regimes. Maintaining these flow regimes, as well as attempting to prevent the spread of threatening processes such as alien and translocated species, should be prioritised by relevant management, policy and research agencies and institutions.