Document ID: chunk:federal_register_of_legislation:F2019L00106:body:0:p50
Version: federal_register_of_legislation:F2019L00106
Segment Type: other
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Character Range: 133389–136371

abilities and is apparently highly virulent, past impacts on populations have likely been immediate and catastrophic and may have not been detected adequately due to insufficient awareness. It appears that redfin may be developing a resistance (or reducing infection rates) to EHNV (Whittington et al., 2011), but further research is required to ascertain whether Macquarie perch are also developing resistance to the virus.
The ecto-parasitic copepod species, Lernaea cyprinacea (or anchor worm), is a widespread parasite, having been accidentally transferred as a result of human translocation of its cyprinid hosts, notably carp and goldfish, with the expansion of aquaculture (Kabata 1979, cited in Bond 2004). Lernaea is a large, highly modified and specialised copepod that parasitises the gills and skin of fish (Rowland & Ingram 1991). In Australian native fish, the attachment of Lernaea is generally in the gill cavity or at or near the base of fins (Rowland & Ingram 1991). When Lernaea leaves the host fish, a red lesion up to 10 mm long remains at the prior attachment site (Rowland & Ingram 1991). Lernaea has been observed on 'young of the year' Macquarie perch in Cotter Reservoir and in the upper Murrumbidgee River and it is presumed it is impacting recruitment success (Lintermans unpub. data, 2017, cited in Lintermans pers. comm., 2017; NSW DPI pers. comm., 2017). Attachment of the parasite to the caudal fin causes fin split, with the likely impact of reducing swimming capability which is potentially important in predator evasion (Lintermans unpub. data, 2017, cited in Lintermans pers. comm., 2017).
Macquarie perch have been shown experimentally to be highly susceptible to Megalocytivirus infection, which is an emerging threat from the live ornamental fish trade. These viruses represent an array of closely related agents that were first recognised to cause high mortality in aquacultured food and aquarium fish in the 1990s. Megalocytiviruses have low host specificity and appear to be readily carried by freshwater aquarium fish including gouramis, poeciliids and cichlids. In 2003, Dwarf Gourami Iridovirus (DGIV) found in 'presumably' imported dwarf gourami (Trichogaster lalius) in retail shops in Australia was identical to the causative agent for mass mortality in intensively farmed Murray cod (Go et al., 2006). The susceptibility to DGIV of several other native freshwater fish species was subsequently demonstrated by experimental challenge studies (Rimmer et al., 2016). The studies indicated that naïve native fish populations, including Macquarie perch, would be vulnerable to megalocytiviruses should they enter natural waterways through infected ornamental fish (Rimmer et al., 2016).
A recent study  characterised the diversity of major histocompatibility complex (MHC) IIB locus in four Australian freshwater perchichthyid fish, including Macquarie perch (Bracamonte et al., 2015). MHC is a key component of the adaptive immune system