Document ID: chunk:federal_register_of_legislation:F2019L00106:body:0:p35
Version: federal_register_of_legislation:F2019L00106
Segment Type: other
Provision Reference: 
Character Range: 92820–95820

upper catchment (Gray 2010; Vic DEPI 2014a; 2014b; Vic DEDJTR 2015b; VFA 2017). The estimate of Macquarie perch abundance at the time of European settlement for the Loddon River catchment was rated as rare from the lowland zone and abundant in the slopes zone; and rare from the upland zone which is probably a result of the presence of many waterfalls in the upper Loddon River catchment (Trueman 2011). Only a few small streams penetrate into the montane zone of the Loddon River catchment and there are no records of larger native fish being present in this zone (Trueman 2011). SRA1 and 2 recorded no Macquarie perch in surveys at 20 sites in 2004 and 18 sites in 2007 across the Loddon River catchment (Davies et al., 2008; 2012). SRA rarity scores for the species in the catchment were: rare in the lowland, and; occasional in the merged slopes/upland/montane zone (MDBA 2017).

    6.2 Threats

6.2.1 Habitat degradation
Habitat degradation can include processes such as sedimentation and destruction and/or removal of rock and woody habitats (snags) essential for egg development and hatching stages of Macquarie perch.
Native fish fauna in the upper reaches of Murray-Darling Basin catchments, such as the Macquarie perch, which release eggs at downstream ends of pools to wash into riffle zones and settle into interstitial spaces between rocks and pebbles (Cadwallader & Rogan 1977; Cadwallader 1978; Tonkin et al., 2010), have probably been the most directly affected by increased sedimentation (Harris 1995). Sedimentation has been considered has one of the most important reasons for the decline of Macquarie perch populations (Cadwallader 1978; 1979).
While sediment and other suspended materials in the water column are natural components of rivers and streams, as erosion and decay processes will deliver sediment to streams even in pristine landscapes, land-use changes (especially poorly-managed agricultural practices, proliferation of rabbits in the late-1800s/early-1900s, forestry, road construction and maintenance, mineral extraction, construction activities and increased fire frequency or catastrophic bushfires) have resulted in an increase in anthropogenic fine sediment deposition in Australia (Walker et al., 1986; Waters 1995; Burkhead et al., 1997; Wood & Armitage 1997; NSW DPI pers. comm., 2017). Sedimentation is one of the most widespread physical disturbances degrading the habitats within Australian rivers (Commonwealth of Australia 1996, cited in Harris & Silveira 1999). Since European settlement, river sediment loads are estimated to have increased by 10–50 fold, with gully, riverbank and sheet erosion delivering, on average, over 120 million tonnes of sediment to Australian streams each year (NLWRA 2001). Increased levels of sediment can adversely affect many aspects of freshwater ecosystems by reducing water quality, modifying the morphology, ecology and physical form of streams and altering the physical, physiological and behavioural responses