Document ID: chunk:federal_register_of_legislation:F2019L00106:body:0:p48
Version: federal_register_of_legislation:F2019L00106
Segment Type: other
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Character Range: 128038–131018

al., 2016a). A laboratory study on the effect of temperature on <24 hour and one-week old Macquarie perch larvae found that <24 hour individuals were significantly affected by water temperatures below 12°C, while one-week old individuals were comparatively resilient (Raymond & Ryall 2017b).
Seasonal variation in water temperature is an important trigger for many native freshwater fish species to spawn (Milton & Arthington 1983; 1984; 1985; Koehn & O'Connor 1990b). Most native species breed over the warmer months and require relatively warm temperatures to induce spawning (Lake 1967b; Llewellyn 1971; Rowland 1983; Cadwallader & Gooley 1985).
A 2002 study demonstrated that the egg survival of a number of native species including Murray cod, golden perch, silver perch and freshwater catfish (Tandanus tandanus) was reduced by temperatures below 15°C (Lyon et al., 2002). Koehn et al. (1995) attribute the loss of species such as Murray cod and Macquarie perch in the Mitta Mitta River downstream of Dartmouth Dam to coldwater pollution. Thermal pollution affects fish populations by preventing seasonal warming to critical spawning temperatures, temperature shock to eggs and larvae following sudden high volume releases, inhibited activity, growth, and disease resistance, reduced egg and larval survival, and delayed maturity (Burton & Raisin 2001; Koehn 2001; Astles et al., 2003). In Australia, the most widely recognised effect of thermal pollution is that of depressed summer temperatures on native fish populations (Ryan et al., 2001).
Cold water pollution is likely to have had a significant impact on the distribution of the Macquarie perch. Cold water releases occur annually during critical spawning intervals and threatens the survival of Macquarie perch juveniles and eggs. Reduction of cold water pollution through strategies to reduce temperature stratification of water storages and/or to release water that more closely resembles the natural flow and temperature regime of rivers are likely to have a positive effect on the Macquarie perch.

6.2.5 Disease and parasites
The globally-widespread disease – Epizootic Haematopoietic Necrosis Virus (EHNV) represents a serious threat to Macquarie perch. EHNV was first isolated in Australia from juvenile redfin, sourced from Lake Nillahcootie in 1984, near Benalla in northeastern Victoria (Langdon et al., 1986). Potential carriers (vectors) for EHNV include redfin and rainbow trout (Whittington et al., 1999; 2007).
In New South Wales, EHNV was first detected in redfin in Blowering Dam and Lake Hume in 1986 and then was subsequently found in specimens in Burrinjuck Dam in 1990, from Lake Burley Griffin in 1991 and 1994 and from Googong Reservoir in 1994 (Whitting et al., 1996). These historical outbreaks suggest that the distribution of EHNV in redfin has extended upstream in the Murrumbidgee River system (Whittington et al., 1996). It is highly likely that the upstream Murrumbidgee River, Googong