A medium to large fish with a deep, laterally compressed body. Maximum size 23 kg and 760 mm; usually less than 400 mm and 4 kg. The body colour is generally olive-green with a yellow or cream belly. The mouth is large with the lower jaw protruding slightly. The tail is rounded.
Golden perch is predominantly found in lowland, warmer, turbid rivers, with juveniles in the lower Murray and the northern MDB also recorded from inundated ephemeral floodplain billabongs, and anabranches during summer flooding, but rarely recorded in these habitats in the mid and upper Murray. A main channel specialist, it prefers deep, pool habitats (water velocities of <0.31 m/sec) with a high affinity for instream wood higher (> 1.5m) up into the water column. At night, habitats with higher surface flow were used. The species is long-lived; maximum validated age is 26 years, although most individuals in a population are <~10 years of age (but a significant number can be 10-20 years old). Males are mature at 2 years and females at 4 years, and in the southern MDB are generally thought to spawn with increased flow during spring and summer at water temperature ≥17°C and in the northern Basin at ≥23°C. Spawning has also been recorded during relatively stable, bankfull irrigation flows and within channel river rises in the Murray River, and in the Menindee Lakes, spawning has been recorded in May-September. The Menindee lakes form an important habitat where larval golden perch can enter from riverine habitats and quickly grow, before moving back into downstream and upstream riverine habitats. Spawning significantly increased in the Murray during a 2005 environmental water release. Following the end of the Millennium Drought in 2010 increased abundance of juvenile Golden perch in the Murray at Chowilla and in the Edward-Wakool rivers was likely the result of spawning during flooding in the Darling River and subsequent displacement of eggs and larvae downstream, and upstream recolonisation of juveniles. Golden perch are highly fecund, with a 2.3 kg female holding up to 500,000 eggs. Water-hardened eggs are large (~3–4 mm diameter), semi-buoyant and drift downstream. Hatching occurs after 1–2 days and newly hatched larvae are ~3.5 mm long. Regular breeding has been recorded in some lakes in the Canberra region (Googong, Lake Burley Griffin), but these events are insufficient to support viable fisheries. Golden perch are a highly mobile species, operating at large landscape scales over their life cycle and in the Murray River displayed the largest movements (when compared to Murray cod, Trout cod and Carp) with more Golden perch moving on a ‘continual’ basis. However, movement patterns vary by individual with faster-growing fish in their early life more likely to be ‘movers’ than ‘stayers’. Lateral movements between the Murray and associated floodplain wetlands are common. Adult and immature fish are migratory and extensive adult upstream movements of more than 1,000 km have been recorded, but such movements are uncommon and are generally associated with large floods. Downstream spawning movements have also been recorded. Upstream movements by both immature and adult fish are stimulated by small river rises and most movement in the Murray occurs from October to April. Age structure and birthplace of fish in the middle and lower Darling-Baaka showed that > 90% of lower Darling Golden perch are of local (Darling) origin, but in 2017 ~40% of fish in the mid-Darling were from the Warrego or Culgoa rivers. Similarly, Golden perch in the Murray could have originated in the Murray, Darling or Murrumbidgee rivers, showing that this can be a highly mobile species, either as juveniles or adults. Outside the breeding season, individuals occupy small home ranges of ~100 m for weeks or months before potentially relocating to another home site. In ephemeral semi-arid rivers like the Moonie, the species moves when flows connect waterholes, with ~62% of tagged fish moving, and 38% remaining in a single waterhole over 3 years. The species is an opportunistic carnivore and is the top predator in isolated waterholes of arid rivers. The diet of adult fish consists mainly of shrimps, yabbies, small fish and benthic aquatic insect larvae, but in semi-arid rivers the diet during ‘bust’ times may contain more terrestrial items. Juvenile fish consume more smaller items such as aquatic insect larvae and microcrustaceans.
Golden perch is widespread throughout the lower and mid reaches of rivers in the MDB, but has declined in some upland areas (e.g., it disappeared from the catchment above Lake Burrinjuck and only re-established after successful lake stockings commencing in the 1970s). Although occurring in many valleys, not all valleys have self-sustaining populations. Recruitment and relative abundance of Golden perch were low in the River Murray, SA during the Millennium Drought but increased significantly following widespread flooding in 2010. The species is widely stocked in farm dams, lakes and streams in some States and forms the basis for popular recreational fisheries, but stocking success is variable. 3,459 individuals were recorded from the Sustainable Rivers Audit (2004–2013) occurring in all river valleys except Mitta Mitta, with 86% from lowlands and 12% from slopes elevational zones. 4,146 individuals have been captured in the MDB Fish Survey (2014/15–2021/22), from all river valleys except Kiewa and Upper Murray.
River regulation has disrupted migrations and spawning cues, and cold-water pollution has eliminated some populations below large dams. Barriers to migration and recolonisation posed by weirs and dams are also threats to upstream and downstream movements of all life stages, including larvae which suffer substantial mortality (up to 95%) from passing through undershot weirs. Overfishing in refuge waterholes in ephemeral rivers removes the breeding adults. Genetic investigations have shown mixing of Lake Eyre and Fitzroy Basin Golden perch with MDB fish has occurred (possibly via stocking). This pollutes MDB genetics and may lead to ecological and evolutionary consequences (especially as Golden perch in Lake Eyre, Fitzroy, and Murray–Darling basins are considered different cryptic species).
Attard et al. 2022b; Barrow et al. 2021; Baumgartner et al. 2006; Beheregaray et al. 2017; Conallin et al. 2011; Crook 2004; Crook et al. 2001; Ebner et al. 2009b; Ferguson & Ye 2012; Hunt et al. 2010; King et al. 2005, 2016; Koehn & Harington 2005; Koehn & Nicol 2014, 2016; Koehn et al. 2020a; Koster & Crook 2017; Koster et al. 2014a; Llewellyn 2008, 2014; Mallen-Cooper & Stuart 2003; Marshall et al. 2016; Nixon et al. 2022; O’Connor et al. 2005; Phillips 2003; Reynolds 1983; Sternberg et al. 2008; Stuart et al. 2021; Thiem et al. 2022; Trueman 2011; Ye 2005; Zampatti et al. 2015, 2018, 2021a,b; Zampatti and Leigh 2013a, b.
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