Document ID: chunk:federal_register_of_legislation:F2019L00106:body:0:p12
Version: federal_register_of_legislation:F2019L00106
Segment Type: other
Provision Reference: 
Character Range: 32135–35095

27°C (Trueman pers. comm., cited in Trueman 2007).
The species requires a temperature rise in spring months, generally to at least 16°C for spawning to occur, but it is possible that they can spawn at lower temperatures (Cadwallader & Rogan 1977; Harris & Rowland 1996; Lintermans 2007; Koster et al., 2014; Tonkin et al., 2016a). Recent observations of the species in King Parrot Creek and the Yarra River found that temperature had a significant positive influence on spawning intensity, with the greatest abundance of eggs recorded when mean daily water temperatures exceeded 18 C (Tonkin et al., 2016a).
Historical records indicate that Macquarie perch inhabited many types of riverine habitat that have now been extensively modified. However, Gilligan et al. (2010) summarising research in the Lachlan River proposed that Macquarie perch are –
    "… riverine fish most abundant in reaches > 200m altitude. The species is heavily dependent on the availability of flowing mesohabitats (runs and/or riffles) and small complex rock piles (aggregations of 0.5–1 m diameter boulders) to provide cover. Extensive lengths of undercut banks in reaches with low coverage of flowing mesohabitats or limited small complex rock cover are detrimental. Depth, substratum type, riparian vegetation cover and aquatic macrophyte cover have little influence on the probability that Macquarie perch will occupy a reach."
A strong positive association of Macquarie perch abundance/biomass in Hughes Creek has been recently reported between within stream woody habitat, riparian vegetation and water depth (Tonkin et al., 2016c).
The removal of rock and woody snags, introduction of aquatic pests, siltation and degraded water quality have likely contributed to the loss of quality habitat for Macquarie perch. Given that Macquaire perch lay eggs which settle into interstitial spaces between rocks and pebbles (Cadwallader & Rogan 1977; Cadwallader 1978; Tonkin et al., 2010), low silt coarse spawning substrates are critical for egg development. It is worth noting that the introduced fish species, brown and rainbow trout, also require such substrates (Harris 1995) potentially competing for habitat in areas where these species co-occur with Macquarie perch.
Habitat critical to the survival of the Macquarie perch can therefore be described as all areas within the species' range which are characterized by flowing runs or riffles and small complex rock piles, and in some waterways, instream woody habitats.

    4.3 Reproductive biology

In Murray-Darling Basin rivers, Macquarie perch tend to spend most of their time in deep holes and move to spawn during spring and early summer (from September through 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