Document ID: chunk:federal_register_of_legislation:F2019L00106:body:0:p13
Version: federal_register_of_legislation:F2019L00106
Segment Type: other
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Character Range: 34834–37650

to mid-January) when water temperatures range between 16–20°C (Koehn & O'Connor 1990a; Ingram et al., 2000; Gilligan 2005; Tonkin et al., 2010; 2016a). Fish in lakes or impoundments tend to aggregate at the mouths of suitable feeder streams awaiting appropriate water temperatures (>16.5°C). When the water reaches the required temperature the fish move to appropriate riffle habitat to spawn and then return to the lake or impoundment upon completion of spawning activities or when water temperatures fall below 16.5°C (Wharton 1968; Cadwallader & Rogan 1977; Cadwallader 1977; 1979).
While historical observations indicated that Macquarie perch have a preference for spawning in upper reaches of catchments in Victoria and the Shoalhaven River (Bishop 1979; Cadwallader 1979), recent observations have indicated that populations are reproducing at locations both upstream and downstream of Goorum Falls in the Seven Creeks system in Victoria (ARI unpub. data, cited in ARI pers. comm., 2017). Running ripe Macquarie perch were collected from the Barmah Lakes area during studies in 1937 suggesting that the species may be able to spawn in some circumstances in lowland conditions (Cadwallader 1977), though the requirement for silt-free substrates probably remains.
Murray-Darling Basin Macquarie perch have estimates of age and size at sexual maturity varying from 1–2 years and 117–210 mm for males and 3–4 years and 100–300 mm for females (Cadwallader 1984; Douglas et al., 2002; Lintermans 2007; Tonkin et al., 2009). Fish from the coastal eastern drainages tend to have a smaller size at sexual maturity. Ripe females of 100 mm total length have been reported from the Hawkesbury-Nepean and Shoalhaven river systems  in New South Wales (Dufty 1986) and ripe males as small as 80 mm total length have been captured in the Georges River (Knight 2010; Knight & Bruce 2010). Observations of running ripe males have been observed in a shallow, riffle area at the tail end of a large pool in the Georges River, and contrastingly running ripe females have been observed attempting to move upstream in the Kowmung River and at Pheasants Nest Weir (which now has a fishway) on the Nepean River (Knight & Bruce 2010).
Fecundity is estimated at 32 000 eggs per kilogram of fish (Wharton 1973) hence a large (3.5 kg) female may produce up to 110 000 eggs. Eggs are cream coloured, approximately
1–2 mm in size and adhesive, and are usually found amongst gravel and stones in riffle areas approximately 50–75 cm deep with a flow rate of less than 1 m/s. Hatching usually occurs after 10–11 days at water temperatures ranging from 15–17oC (Lintermans 2007). Newly hatched yolk sac larvae shelter amongst pebbles (Cadwallader & Rogan 1977).
Macquarie perch larvae in the Cotter River above Cotter Reservoir in the Australian