Lower Murray-Darling Catchment Action Plan 2004 – 2016: Fish Community Monitoring Report Card for 2006/07.
Gilligan D (2008) Lower Murray-Darling Catchment Action Plan 2004 – 2016: Fish Community Monitoring Report Card for 2006/07. NSW Department of Primary Industries – Fisheries Research Report Number 22. 57 pp. ISSN 1449-9959.
Attention: The version of the report printed and distributed in November 2008 was subsequently revised in January 2009. The revisions include substantially more detail in the discussion of the report. The pdf available below is the revised version which supersedes existing printed copies of the report.
|Lower Murray-Darling Catchment Action Plan 2004 – 2016: Fish Community Monitoring Report Card for 2006/07.
The Lower-Murray Darling Catchment Action Plan (CAP) identifies Riverine Health as a Catchment Target: “An identifiable nett improvement in riverine health across the Lower Murray Darling Catchment by 2015”. This annual report presents the freshwater fish data collected in 2007 and compares them with benchmark data collected in 2004 and monitoring data from 2006, assesses progress towards the CAP fish community targets and discusses patterns observed in the context of other riverine health targets regarding algal blooms, hydrological condition and salinity.
The same sampling protocols used in 2004 and 2006 were used in 2007. Fish sampling was undertaken at 33 sites in May-July 2007. At a catchment level, all the fish species recorded in 2004 and 2006 were also collected in 2007 and no new fish species were recorded. Nine native species formerly resident in the Lower Murray-Darling CMA area remain undetected since at least 2004.
The CAP target of a 55% improvement in the native : alien species ratio was not met in any catchment zone in 2007. Rather, there was a significant decline in the native : alien species ratio in upper and lower Murray River sites and across the CMA area as a whole. Since 2004, native species have been retracting in distribution while alien species have been expanding.
The CAP target of a 25% improvement in the native : alien abundance ratio was not met in any riverine reaches or the Lakes & Reservoirs zone in 2007. The ratio had improved in wetland sites, but the result was non-significant and highly variable across wetlands. However, there was a significant decline in the native : alien abundance ratio across the catchment as a whole. Since 2004, native species have been declining in abundance with an average 213 individuals of native species per site in 2004 and only 127 per site in 2007.
The CAP target of a 25% improvement in the native : alien biomass ratio was not met in any catchment zone or across the catchment as whole in 2007 as there were no statistically significant changes in the ratio in any catchment zone or across the catchment as a whole.
The analyses suggest that any management actions implemented up until May 2007, and/or the extent of the works involved, have not been sufficient to result in demonstrable progress towards the three CAP targets for fish community ‘nativeness’. The persistent drought in this part of the Murray Darling Basin has probably contributed to this disappointing conclusion. Recovery actions for threatened species, ‘fish-appropriate’ wetland watering activities, utilising environmental water allocations to initiate recruitment of riverine fishes, investigating and remediating the lack of golden perch recruitment in the CMA area and implementing carp control activities are recommended as strategies that might contribute to progress in achieving CAP targets by 2016. Further, there are difficulties associated with presenting and analysing ratios and it is recommended, therefore, that the CMA adopt alternative targets based on the proportion of native fish in a sample rather than the ratio of native to alien fish.