Biodiversity

Species Profile and Threats Database


For information to assist proponents in referral, environmental assessments and compliance issues, refer to the Policy Statements and Guidelines (where available), the Conservation Advice (where available) or the Listing Advice (where available).
 
In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.

EPBC Act Listing Status Listed as Endangered
Recovery Plan Decision Recovery Plan required, this species had a recovery plan in force at the time the legislation provided for the Minister to decide whether or not to have a recovery plan (19/2/2007).
 
Adopted/Made Recovery Plans Recovery plan for the Oxleyan pygmy perch (Nannoperca oxleyana) (NSW Department of Primary Industries (NSW DPI), 2005j) [Recovery Plan].
 
Policy Statements and Guidelines Survey guidelines for Australia's threatened fish. EPBC Act survey guidelines 6.4 (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2011i) [Admin Guideline].
 
Federal Register of
    Legislative Instruments
Declaration under s178, s181, and s183 of the Environment Protection and Biodiversity Conservation Act 1999 - List of threatened species, List of threatened ecological communities and List of threatening processes (Commonwealth of Australia, 2000) [Legislative Instrument].
 
State Government
    Documents and Websites
NSW:Endangered species - Oxleyan pygmy perch (NSW Department of Primary Industries (NSW DPI), 2005f) [Internet].
State Listing Status
QLD: Listed as Vulnerable (Nature Conservation Act 1992 (Queensland): May 2014 list)
Non-statutory Listing Status
IUCN: Listed as Endangered (Global Status: IUCN Red List of Threatened Species: 2013.1 list)
Scientific name Nannoperca oxleyana [64468]
Family Percichthyidae:Perciformes:Actinopterygii:Chordata:Animalia
Species author Whitley, 1940
Infraspecies author  
Reference  
Distribution map Species Distribution Map

This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.

Illustrations Google Images
http://www.fisheries.nsw.gov.au/thr/species/fn-oxleyan-pygmy-perch.htm ;
http://www.asfb.org.au/research/tsp/tfp_oxpperch.htm

Scientific name: Nannoperca oxleyana

Common name: Oxleyan Pygmy Perch

At different times, Nannoperca spp. have been placed in their own family, Nannopercidae, in the family Kuhliidae (with the flagtails, genus Kuhlia) and in the family Percichthyidae (freshwater basses and cods of southern Australia and South America). At a sub-familial level, the group has been variously split into three genera (Edelia, Nannoperca and Nannatherina) or two genera (Nannoperca and Nannatherina), with E. obscura and E. vittata also placed into Nannoperca (Kuiter & Allen 1986; Kuiter et al. 1996; Llewellyn 1980; Sanger 1978).

Recent genetic evidence (Jerry et al. 2001) supports the placement of the pygmy perches within the family Percichthyidae, and the recognition of the genera Nannoperca and Nannatherina only.

The Oxleyan Pygmy Perch is a mobile species that is often observed individually or in pairs and sometimes as small groups, but does not form schools. Groups are generally comprised of smaller individuals.

Oxleyan Pygmy Perch are usually light brown to olive in colour (darkest on back, sides paler) and mottled, with three to four patchy, dark brown bars extending from head to tail, and a whitish belly. The gill cover (opercular) has a blue iridescence and there is a conspicuous dark round spot with an orange margin at the base of the tail. The scales have dusky margins and the fins are mainly clear. There is a blue ring around the eye. During breeding the dorsal, pelvic and anal fins darken and the lateral stripes and tail turn scarlet (Arthington & Marshall 1996; Kuiter et al. 1996; Thompson et al. 2000). They can grow to about 60 mm in length, but are more commonly around 35 mm (Allen 1989a; McDowall 1996). Oxleyan Pygmy Perch are similar in appearance to other pygmy perch species and to juveniles of other perch-like species.

The Oxleyan Pygmy Perch have a restricted and patchy distribution, and are known from about 20 localities in Queensland (Arthington et al. 1996; Thompson et al. 2000) and approximately 25-30 localities in northern New South Wales (NSW) (including 13 creeks and 12 lakes surveyed to the north and west of Evans Head) (Knight 2000). The species is found in coastal heath or 'wallum' habitats (Leggett 1990) along the north coast of NSW and the south coast of Queensland including Moreton Island (Lake 1971), Fraser Island (Wager 1992) and North Stradbroke Island (Arthington et al. 1996). Merrick and Schmida (1984) noted that its mainland range extended from the Richmond River system near Lismore, NSW, northwards to the dune lakes between the Maroochy and Noosa River systems.

In northern NSW, Oxleyan Pygmy Perch have been recorded in the Wooli area from Lake Minnie Water in 1995 (Lawrence 1998), and again in 2001. Furthermore, surveys undertaken by ANGFA (Australian & New Guinea Fishes Association), and Southern Cross University have located four additional waterbodies containing Oxleyan Pygmy Perch in the Wooli area, with a new record from Haleys Creek, near Brooms Head. An intensive survey of the Evans Head area (northern NSW) in 2000 resulted in the capture of 566 perch from 25 water bodies in and around Broadwater National Park (Knight 2000). This makes the Evans Head area one of the most important known habitats for the species (NSW DPI 2005j).

Until recently, the distribution of Oxleyan Pygmy Perch in NSW (particularly the northern, southern and western limits of their range) was unknown. Survey work undertaken as part of the draft recovery plan has provided a clearer picture of their distribution by focusing on unsurveyed areas between Myall Lakes National Park (south of Taree) and the NSW-Queensland border that may contain Oxleyan Pygmy Perch habitat (Knight 2001a). The surveys aimed to identify sub-catchments likely to contain Oxleyan Pygmy Perch, however it is possible that some isolated populations may have been missed. There are many unsurveyed lakes, streams and swamps in Bundjalung and Yuraygir National Parks, NSW, where Oxleyan Pygmy Perch may exist. These water bodies will be surveyed as part of the implementation of the recovery plan.

The species may extend further north than recorded, although limited surveys, conducted from Tin Can Bay (Queensland) north to the heathlands of Shoalwater Bay near Byfield, have not established this (Arthington 1996). Several species with similar habitat requirements to the Oxleyan Pygmy Perch, including the Honey Blue-eye (Pseudomugil mellis) and Soft-spined Rainbowfish (Rhadinocentris ornatus), have been found in this region (Woods & Marsden 2004). Oxleyan Pygmy Perch may also extend further south than presently known but this has not been confirmed. Soft-spined Rainbowfish for example, share much of their distribution with Oxleyan Pygmy Perch and have been found 38 km south of Corindi in Boambee Creek, near Coffs Harbour, NSW. Suitable areas of habitat appear to occur all the way down the coast to Crowdy Bay National Park (near Taree) or further. However, broad-scale surveys to establish the southern distributional limits of the species have been unable to locate Oxleyan Pygmy Perch south of Yuraygir National Park, near Grafton, NSW (NSW DPI 2005j).

The distribution of Oxleyan Pygmy Perch on the mainland appears to be disjunct, as the species has never been recorded within the 250 km of coastline from Rileys Hill, just north of Evans Head, in northern NSW to Deception Bay in south-east Queensland (Knight 2000; Knight 2001a). Even within areas of their habitat, their distribution is patchy and despite extensive searching, the species has only been found in a relatively small number of locations (NSW DPI 2005j).

While little information exists on their tolerance to disturbance, habitat degradation or pollution (NSW DPI 2005j), Oxleyan Pygmy Perch were found within shallow artificially constructed drains in northern NSW, suggesting that they may be capable of surviving in more degraded areas (Knight 2000). However, the species is mainly restricted to unpopulated or isolated areas where human interference is absent or minimal (Leggett 1990).

Historical reports of Oxleyan Pygmy Perch come from the southern end of their known range in the Wooli/Corindi area, including Wooli Creek and Cassons Creek in 1976 and Tick Gate Swamp in 1977. In 1975 and 1977 the species was also found in Lake Hiawatha, just north of Wooli (Llewellyn 1980). However, further surveys of this lake conducted in 1975-79 and again in 1993 failed to locate the species.

Lake (1978) noted that this species was an excellent aquarium fish and has been bred by fish hobbyists.

Oxleyan Pygmy Perch are generally not considered to be a prolific species, with low numbers captured at most sites where they occur. However, in a survey of creeks on Morton Island, including Spitfire, Tempest, Marcus and Coondoo creeks, Oxleyan Pygmy Perch represented 20% or more of the fish species collected (Arthington 1996).

Local environmental conditions can have a major effect on this species abundance. For example, during the survey of a creek near Evans Head, NSW, 208 Oxleyan Pygmy Perch were collected (Knight 2000). When the same creek was re-surveyed several years later in 2001 no Oxleyan Pygmy Perch were found (Knight 2001a). A dirt road crosses the creek and several months after initial sampling the creek had virtually dried up (Knight 2001b).

Oxleyan Pygmy Perch populations on Fraser Island (Queensland) are considered to be reasonably secure. Other populations occurring in Carland Creek and the Upper Noosa River (Queensland) occur within the Cooloola National Park (Arthington & Marshall 1996). Populations on Moreton Bay vary in their accessibility and susceptibility to habitat disturbance (Arthington & Marshall 1996). The remaining NSW populations are located within the Broadwater, Bundjalung and Yuraygir National parks in the Evans Head region (Knight 2000). Subtle differences in habitat and water quality, chance dispersal and extinction events, and the effects of recent habitat loss or degradation, may have contributed to the patchiness of this species throughout its geographical range (Arthington et al. 1996).

Wallum Vegetation

The Oxleyan Pygmy Perch occurs in dystrophic, acidic freshwater systems which drain through sandy coastal Banksia spp-dominated heath or wallum vegetation assemblages (Arthington & Marshall 1993; Leggett 1990; Wager 1992, Knight & Arthington 2008).

The coastal wallum heathlands where Oxleyan Pygmy Perch occur are unique, regionally significant communities that support a diversity of native flora and fauna. The flora includes species from families such as Proteaceae (including the endemic 'wallum banksia' Banksia aemula), Epacridaceae (Australian heaths), Myrtaceae, Rutaceae, Fabaceae, Euphorbiaceae, Restionaceae and Cyperaceae (NSW DPI 2005j). Wallum country has a well-distributed annual rainfall (1016—1778 mm) and freshwater lakes, creeks and wetlands are a prominent landscape feature (Arthington & Marshall 1993). Oxleyan Pygmy Perch have also been found at several sites with different habitat characteristics such as creeks that run into adjacent areas out of wallum heath. For example, they have been recorded from an intermediate eucalypt forest/heath community and from rainforest/melaleuca swamp (Knight 2001a), and from among saltrushes in an estuarine creek with high salt levels (conductivity: 8860 µs/cm) (Harrison et al. 2002).


Water Chemistry

The specific habitat requirements of the Oxleyan Pygmy Perch include fresh, acidic waters and abundant aquatic vegetation (NSW DPI 2005). The pH of Oxleyan Pygmy Perch habitat usually ranges from 5.9-7.2, depending on recent rainfall and runoff (Wager 1992), though values as low as 3 have been recorded (Arthington et al. 1996). These waters are usually organically stained and highly coloured (Wager & Jackson 1993), but are occasionally clear (Arthington & Marshall 1993). The Oxleyan Pygmy Perch is usually restricted to waters of low conductivity (low salt) (<330 µs/cm) and low flow environments (<0.3 m/sec) (Knight 2000). This species can tolerate water temperatures of 12—28 °C, and spawning occurs at temperatures greater than 20 °C (Wager 1992).

Riparian and In-stream Habitat

Oxleyan Pygmy Perch are known to inhabit ponds and creeks (Allen 1989a) usually with adense emergent and submerged marginal vegetation (60—80% cover), leaf litter beds, and occasionally woody debris if present (Arthington et al. 1996; Thompson et al. 2000). They are often found amongst fine rootlets of riparian vegetation growing into the stream (Wager & Jackson 1993) including stands of emergent sedges Lepironia articulata, Gaphnia sp., and Juncus sp., beds of submerged sedges Eleocharis ochrostachys and growths of Nymphaea sp., Chara sp. and Utricularia sp. (Arthington et al. 1996). In northern NSW, the paperbark Melaleuca quinquenervia occurred at 80% of the sites where Oxleyan Pygmy Perch were present, and assemblages of native riparian vegetation and aquatic macrophytes were found in association with the fish at many of the sites (Knight 2000). The presence of woody debris, undercut banks and leaf litter also provides protection for the species for the species and may be an important habitat feature. Other species of the genus Nannoperca prefer habitats with dense woody cover (Knight & Arthington 2008).

In the Noosa River, Arthington and Marshall (1993) noted that submerged sedge beds of Eleocharis ochrostachys in sheltered areas and tributaries were the preferred habitat. The species is often found where aquatic macrophytes or undercut banks provide cover (Arthington et al. 1996). Oxleyan Pygmy Perch were once common in many freshwater dune lakes (Lake 1978), where they occurred in reeds near the lake margins (Llewellyn 1980).

The Oxleyan Pygmy Perch tends to occupy the bottom 70% of the water column. Smaller individuals tend to be higher up in the water column. Cover is the important factor in environments where surface (i.e. avian) and aquatic predators (fish such as Striped Gudgeon and eels) are present (Arthington et al. 1996). Aquatic plants may also reduce the impact of short periods of high flow that can displace smaller fish some distance downstream (Arthington 1996). In aquarium situations, they prefer water temperatures of 21—23 °C and a pH of 6.2—6.6 (Leggett & Merrick 1987).

The reproductive biology of the Oxleyan Pygmy Perch is poorly known. On Moreton Island, Queensland, they spawn from about September—October to April—May in the Noosa River and some of its tributaries, and from September—October to December in Spitfire Creek. It is thought that most populations spawn between October and December (Arthington & Marshall 1993; Arthington et al. 1996). Spawning is probably stimulated by rising water temperatures (NSW DPI 2005j).

Females mature at 3 cm and males mature at 2.7 cm (Leggett & Merrick 1987). Breeding individuals display distinctive breeding colours, with red lateral stripes, a red tail and black dorsal, anal and pelvic fins. Courtship and mating involve a pair casually approaching each other and as they near, quickly shuddering and releasing eggs and milt (sperm). Spawning is protracted, with a few eggs laid daily over several days (Wager 1992). This method of spawning allows pygmy perch to produce a greater number of eggs in the breeding season than would otherwise be predicted from their body size (Knight 2000; Wootton 1992). Two ripe (egg-bearing) females collected in Spitfire Creek (Moreton Island) in January 1995 had a range of 225—270 eggs. However, these values may not be representative of the average fecundity as the fish were sampled near the end of their reproductive activity for the season (Arthington et al. 1996).

The eggs are adhesive and demersal, which means they sink or settle near the bottom, sticking to aquatic vegetation or other substrate (Arthington & Marshall 1996; Kuiter et al. 1996; Thompson et al. 2000; Wager 1992). The deposition of demersal eggs in protected areas would tend to shelter eggs and young fish from the full force of water movements and from exposure to aquatic and avian predators (Arthington et al. 1996). The eggs hatch in 1—3 days (Leggett & Merrick 1987) and larvae begin feeding 1—2 days after hatching (Wager 1992). In captivity, fish fry (juvenile fish) reached a size of 1.8 cm in ten weeks (Leggett 1990). Similarly, aquarium bred fry reached 2 cm in 7—8 weeks and matured in four to five months (Wager 1992). Fry grow rapidly, but most fish only survive for about one year and a few fish possibly live to an age of three to five years (Knight 2000).

The Oxleyan Pygmy Perch feeds primarily on aquatic insects and their larvae (Allen 1989a). In aquarium situations, they have a preference for live foods such as freshwater plankton containing Cladocerans (freshwater crustaceans, i.e. Daphnia), Ostracods (tiny shrimp), Copepods (crustaceans), Rotifers (microscopic plankton) and other invertebrates (Wager 1992). The stomach contents of 122 Oxleyan Pygmy Perch collected from the Noosa River (Queensland) in 1990—91 showed that the diet in the wild consisted of Copepods, Cladocera and Caridina (Crustaceans) and aquatic insects (especially Chironomidae or non-biting midges), plus a small component of algal material and other plant tissues, and a few terrestrial insects. There was slight seasonal variation in the diet (Arthington & Marshall 1993).

The stomach contents of 56 individuals from Spitfire Creek (Moreton Island, Queensland) showed that the dietary diversity was high and was composed principally of Cladocera (found in 61% of individuals), the Decapod shrimp, Caridina (Crustacea), Acarina (related to mites and ticks) and the larvae of various aquatic insects. Terrestrial sources of food (e.g. small insects) were found to be relatively unimportant in the diet of Spitfire Creek fish. Desmids (green algae) were consumed by one individual but there was no evidence of ingestion of filamentous algae. Fish collected from Eleocharis (sedge) beds had a more varied diet than those caught in large aquatic (macrophyte) plant beds.

The Spitfire Creek study also showed a dietary overlap between Oxleyan Pygmy Perch and the Empire Gudgeon (Hypseleotris compressa). The highest degree of overlap in diet composition between these two species occurred in shallow Eleocharis beds and deep macrophyte beds (Arthington et al. 1996). A high level of similarity in food resource use by these two numerous species in deep macrophyte beds (numbers were low in shallow vegetated habitats) could result in competition between the species if the shared resources are in short supply. However, results suggest that these species were able to co-exist in relatively large numbers in Spitfire Creek despite this dietary overlap (Arthington et al. 1996).

In northern NSW, the Oxleyan Pygmy Perch is often found in association with the Soft-spined Rainbowfish (Rhadinocentrus ornatus) (Knight 2000). The Soft-spined Rainbowfish could thus be used as an indicator species for habitats which may support populations of Oxleyan Pygmy Perch (Arthington et al. 1996). No direct competition for food resources was evident between these two species (Knight 2000).

No known movements or migrations have been observed for the Oxleyan Pygmy Perch. The large majority of waterbodies found to support populations of this species in northern NSW occur on low-lying coastal plains. Floods intermittently connect these waterbodies, which potentially facilitates the dispersal of Oxleyan Pygmy Perch (along with other aquatic organisms) within and amongst them (Knight 2000). The genetic analysis of populations from Lake Jabiru and Spitfire Creek (Moreton Island) and the Noosa River (Queensland), two very extensive systems compared to small coastal creeks, supports the view that fish move, mix and interbreed within individual drainage systems (Hughes et al. 1996).

Knight & colleagues (2007) give a detailed description of the most suitable methods of survey for this species and discuss adequate survey effort and the issue of destructive sampling techniques. The study highlights the benefits of utilising multiple survey techniques in regards to mimising the chance of a false absence. The selectivity of one survey method (ie: trapping) is offset by another method (ie: electrofishing or seine netting). Therefore, wherever it is considered to be feasible, multiple methods should be employed.

Trapping

Trapping is considered to be the most effective single method for sampling small, cryptic fish species, such as the Oxleyan Pygmy Perch. Rectangular, collapseable frame traps, measuring 250 x 250 x 450 mm, with 3mm mesh and 40 mm openings were found to be effective for sampling the species (Knight et al. 2007). Baiting has not been found to affect catch rates and for logistical reasons, unbaited traps are recommended. The minimum number of traps required to obtain a precise estimate in a particular locality is 10. Traps should be positioned 1.5—2 m apart and left in place for 30 minutes between inspections.

The level of replication of survey sites is contingent on the water course being sampled. If extensive replication throughout a large water course is not feasible, surveys should be targeted to areas where presence of the Oxleyan Pygmy Perch are most likely to be present (if the aim is to determine presence/absence).

Some pygmy perch species can be misidentified due to similarities in appearance. However, the location of the sighting or capture can assist in identifying to the species level. Oxleyan Pygmy Perch have the most northerly distribution of the Nannoperca genus. The Southern Pygmy Perch (Nannoperca australis), Ewen Pygmy Perch (Nannoperca variegata) and Yarra Pygmy Perch (Nannoperca obscura) are endemic to south-eastern Australia. The final two pygmy perch species, Nannatherina balstoni and Nannoperca vittata, are found only in south-western Australia.

Electrofishing

Electrofishing has been demonstrated to also be an effective method of sampling the Oxleyan Pygmy Perch, if conditions are suitable. A backpack electrofishing apparatus should be used; set at 200—500 v, 60 Hz pulsed DC. Electrofishing is a benign and non-lethal sampling method if settings are correct. Voltage should be set as low as possible to attain the desired effect.

Seine netting

Seine netting is less effective than trapping or electrofishing, but also has been shown to result in a higher mortality of captured individuals and damage to habitat. Seine netting is not a recommended survey method for this species when other methods are feasible.

Dip Netting

In waters less than 200 mm in depth (where trapping is not possible), dip netting is a highly effective method. If done with care, dip netting results in low mortality and is considered to be a suitable method for very shallow waterbodies.

Habitat Loss

The most serious threat affecting the Oxleyan Pygmy Perch is habitat degradation and loss. Wallum heath communities once formed an almost continuous band along the eastern coastline from Coffs Harbour in northern NSW, to Bundaberg in southern Queensland. However, the practice of land clearing for urban development, agriculture, forestry and mining has significantly reduced and fragmented these habitats (NSW DPI 2005). Road and bridge construction has increased the sediment load in a number of small coastal creeks along the Sunshine Coast (Arthington & Hughes 1996) and riparian clearing and the channelisation of creeks has also caused disturbance in northern NSW (Knight 2000). The delicate nature of wallum country makes it particularly susceptible to habitat damage. The sandy substrates are rapidly eroded following clearing of vegetation and infilling, and stream siltation usually follows (Wager 1992).

Intact areas of wallum heath are now largely confined to protected areas such as Broadwater, Bundjalung and Yuraygir National Parks in NSW and Cooloola (Great Sandy) and Moreton Island National Parks in Queensland. These protected areas preserve large tracts of wallum heath habitat and most recent reports of this species in NSW have come from water bodies within the parks (NSW DPI 2005j). However, even habitats in protected areas can be degraded through a range of recreational, management or development activities. Examples include run-off from unsealed roads, hazard reduction burning, bushfire fighting activities (where large amounts of debris and water are washed into creeks) and disturbance by recreational users such as four-wheel drive vehicles.

While some important tracts of wallum heaths are protected within coastal national parks, other remaining areas of Oxleyan Pygmy Perch habitat are found on private or Crown land that could be developed in the future (NSW DPI 2005j). Several Oxleyan Pygmy Perch sites are located close to residential areas (or areas zoned for development) and the survival of these populations may be threatened by surface run-off and other activities that degrade river habitats (NSW DPI 2005j).

Areas of comparatively undisturbed wallum heath occurring on freehold land are at risk of being lost through land demands for housing, agriculture and other developments as human populations continue to grow on the north coast of NSW and south-east Queensland. Housing development and road construction projects pose major habitat threats and need to be carefully managed to avoid or minimise impacts (NSW DPI 2005j).

Actions that are particularly threatening to the Oxleyan Pygmy Perch include: sand mining (Leggett 1990), drainage works (NSW DPI 2005j) and water pollution (NSW DPI 2005j).

Barriers to fish passage

Although there is little information about the dispersal mechanisms of Oxleyan Pygmy Perch, it is probable that floods or other high-flow events play an important role. This is because the temporary watercourses or overflows create pathways that carry the species between otherwise isolated bodies of water. This has significant implications for local populations of Oxleyan Pygmy Perch as habitat fragmentation, even on a small scale, could prevent genetic mixing or the recolonisation of areas where populations have been wiped out or are used on a seasonal basis.

Introduced species

Introduced Gambusia (Mosquito Fish) have high environmental tolerance, flexible feeding and habitat needs and adversely affect native species by exhibiting aggressive behaviour, competing for food and space and feeding on the eggs and larvae of native fishes (Arthington & Hughes 1996; Arthington & Marshall 1993; Arthington et al. 1996; Knight 2000; Merrick & Schmida 1984; Wager & Jackson 1993). Gambusia have been linked to the worldwide decline of many endemic fish species, and are now regarded as a pest in Australian waters. While there is little information about the specific impacts of Gambusia on Oxleyan Pygmy Perch, their aggression and ability to survive and compete for food in habitats native to Oxleyan Pygmy Perch, suggest their presence has been detrimental to this species (NSW DPI 2005). Gambusia holbrooki is known to occur in Oxleyan Pygmy Perch habitat in some Fraser Island localities (Woralie and Bogimbah Creeks), the freshwater section of the Noosa River, a tributary of Mellum Creek (Queensland) (Arthington et al. 1996), and in the southern region of the Broadwater National Park (northern NSW) (Knight 2000). Gambusia also co-occurred with Oxleyan Pygmy Perch at 12 sites in northern NSW, usually in disturbed habitats near areas of human settlement (Knight 2000). Although the interactions between the two species are not well known (Arthington et al. 1996) Gambusia display similar habitat preferences to Oxleyan Pygmy Perch in terms of a preference for shallow sandy areas with an abundance of aquatic vegetation, thereby emphasising the threat posed to Oxleyan Pygmy Perch by this pest species (Knight 2000). The occurrence of Gambusiain the above localities could threaten local populations.

Gambusia is the only known exotic fish species to have established self-maintaining breeding populations in freshwater wallum ecosystems (Arthington & Hughes 1996; Coaldrake 1961). Further research on the biology of Gambusiain heathland waters is required to accurately determine the level of threat posed by this species on Oxleyan Pygmy Perch (Arthington et al. 1996). A monitoring strategy to track the population density and range of this introduced species is necessary (Arthington & Hughes 1996).

An exotic weed known as Para Grass (Brachiaria mutica) has invaded the lower reaches of Marcus Creek (South of Noosa, Queensland) and has the potential to impact upon the biodiversity of native aquatic organisms, including the Oxleyan Pygmy Perch (Arthington & Hughes 1996), through reducing light penetration, smothering of native macrophytes, degradation of water quality and aquatic habitats (Knight & Arthington 2008). Additionally, the exotic Whisky Grass (Andropogon virginicus) was present at about one third of the sites that contained Oxleyan Pygmy Perch in northern NSW (Knight 2000). No reports exist of the incidence of diseases and/or parasites impacting on the species (Knight 2000).

Aquarium collecting

Aquarium collecting has the potential to cause population declines (Arthington & Marshall 1996). The number of Oxleyan Pygmy Perch illegally collected for aquariums is difficult to estimate, but aquarium collectors have been observed removing large numbers of indigenous fish from wallum heath water bodies (ANGFA 1986). There have also been several reports in aquarium journals on collecting and keeping pygmy perch. The random collection of Oxleyan Pygmy Perch for aquariums is likely to be harmful to some small, restricted populations of the species. While collection alone is unlikely to remove a complete population, even in highly accessible areas, any reduction in numbers may affect the population's ability to recover from other threats, including floods, pollution, or introduced species such as Gambusia.

Loss of genetic diversity

The loss of genetic diversity is a potential threat to any species that occurs in a small number of isolated populations (Wager & Jackson 1993). The results of a study using allozyme and mitochondrial DNA variation to examine genetic structure in Oxleyan Pygmy Perch populations in south-east Queensland showed that there was little genetic variation within each population but large variation between populations (Hughes et al. 1999). This suggests the opportunities for dispersal are limited among the populations that live in small, specific habitats in different drainage systems.

These results have important implications for the long-term conservation of Oxleyan Pygmy Perch, verifying the need to maintain as many different populations as possible to preserve genetic diversity. The large genetic differences between populations would also have to be considered if fish taken from other areas or bred in aquaria were used to restock any habitat in future. The limited dispersal abilities and isolated populations of the species suggest that once locally extinct, they are likely to remain so (Hughes et al. 1999). Alternatively, the low genetic variability in each drainage system supports the view that fish do move, mix and interbreed within individual drainages (Arthington 1996).


Natural events

Natural environmental changes such as droughts and floods can cause extreme fluctuations in Oxleyan Pygmy Perch populations due to the alterations to available habitat (Knight 2000). Such fluctuations in population densities need to be considered when assessing the seasonal and/or annual abundances of this species, as abundances are likely to vary.

The NSW Department of Primary Industries (DPI) in consultation with the Queensland Environmental Protection Agency/Queensland Parks and Wildlife Service has prepared a National Recovery Plan for the Oxleyan Pygmy Perch (Nannoperca oxleyana). The overall objective of this National Recovery Plan is to prevent the extinction and ensure the recovery and ongoing viability of Oxleyan Pygmy Perch populations (NSW DPI 2005j). The specific recovery objectives recommended by the National Recovery Plan are to:

  • Increase scientific knowledge and understanding about the distribution, habitat, life history, ecology and genetics of Oxleyan Pygmy Perch.
  • Increase community awareness and support of Oxleyan Pygmy Perch recovery actions.
  • Protect and restore essential habitats for Oxleyan Pygmy Perch.
  • Minimise the impacts of introduced fish on Oxleyan Pygmy Perch.
  • Reduce the illegal collection of Oxleyan Pygmy Perch by encouraging and involving aquarium enthusiasts to support recovery efforts.
  • Establish a program to monitor the status of Oxleyan Pygmy Perch and assess the effectiveness of recovery actions.

Oxleyan Pygmy Perch do not have a high profile in the community or among planners and developers. This is partly because they are considered a small, rare fish with no recreational fishing value. In many cases access to accurate information about the species, improved awareness and appropriate planning could avoid many of the impacts on Oxleyan Pygmy Perch caused by human activities (NSW DPI 2005j).

Significant gaps exist in information about the life history, population dynamics, dispersal patterns and genetics of the Oxleyan Pygmy Perch. For example, little is known about why the species is present or absent at certain sites over time. More knowledge about the genetic structure of Oxleyan Pygmy Perch populations and methods of dispersal would help in understanding what effect barriers to their distribution, population fragmentation or changes to topography or hydrology have on the viability of the species. Genetic studies would also provide data that would assist in the conservation of Oxleyan Pygmy Perch genetic diversity and genetic population structure, which is critical to ensuring their long-term viability (NSW DPI 2005j). Further studies are also necessary to determine how populations of the Oxleyan Pygmy Perch in small streams respond to discharge variability, fluctuations in water level and other environmental factors over various time scales (Arthington & Hughes 1996). As riparian vegetation is an important habitat characteristic for this species (Arthington et al. 1996), it is crucial to monitor and eliminate any threats to the destruction of riparian habitat at sites where the species is still known to occur.

Management documents relevant to the Oxleyan Pygmy Perch are at the start of the profile.

The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.

Threat Class Threatening Species References
Agriculture and Aquaculture:Agriculture and Aquaculture:Land clearing, habitat fragmentation and/or habitat degradation The Oxleyan pygmy perch - maintaining breeding populations. Fishes of Sahul. Journal of the Australia New Guinea Fishes Association. 7(2):310-312. (Wager, R., 1992) [Journal].
Biological Resource Use:Gathering Terrestrial Plants:Commercial harvest Threatened fishes of the world: Nannoperca oxleyana Whitley, 1940 (Nannopercidae). Environmental Biology of Fishes. 46:150. (Arthington, A.H. & C.J. Marshall, 1996) [Journal].
Biological Resource Use:Logging and Wood Harvesting:Habitat loss, modification and degradation due to timber harvesting The Oxleyan pygmy perch - maintaining breeding populations. Fishes of Sahul. Journal of the Australia New Guinea Fishes Association. 7(2):310-312. (Wager, R., 1992) [Journal].
Climate Change and Severe Weather:Climate Change and Severe Weather:Reduced rainfall caused by climate change Distribution, populations structure and habitat preferences of the Oxleyan pygmy perch Nannoperca oxleyana (Whitley 1940) near Evans Head, northeastern New South Wales Page(s) 141. Hons. Thesis. (Knight, J.T. , 2000) [Hons. Thesis].
Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat loss, modification and/or degradation Northern Rivers Regional Biodiversity Management Plan (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010p) [State Recovery Plan].
Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat modification, destruction and alteration due to changes in land use patterns Natural Temperate Grassland of the Southern Tablelands of NSW and the Australian Capital Territory in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006abj) [Internet].
Climate Change and Severe Weather:Sea level rise:Inundation associated with climate change Inundation study (Environmental Resources Information Network, 2007) [Database].
Ecosystem/Community Stresses:Indirect Ecosystem Effects:Loss and/or fragmentation of habitat and/or subpopulations Northern Rivers Regional Biodiversity Management Plan (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010p) [State Recovery Plan].
Energy Production and Mining:Mining and Quarrying:Habitat modification through open cut mining/quarrying activities A fish in danger Nannoperca oxleyana. Fishes of Sahul. Journal of the Australia New Guinea Fishes Association. 6(1):247-249. (Leggett, R., 1990) [Journal].
Human Intrusions and Disturbance:Human Intrusions and Disturbance:Human induced disturbance due to unspecified activities Northern Rivers Regional Biodiversity Management Plan (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010p) [State Recovery Plan].
Human Intrusions and Disturbance:Recreational Activities:Disturbance, especially from human recreational activities and development Part C Conservation Status of Nannoperca oxleyana and Recovery Plan. A.H. Arthington, ed. Recovery Plan for the Oxleyan Pygmy Perch Nannoperca oxleyana. Page(s) 97-117. (Arthington, A.H. & J.M. Hughes, 1996) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation by weeds Part C Conservation Status of Nannoperca oxleyana and Recovery Plan. A.H. Arthington, ed. Recovery Plan for the Oxleyan Pygmy Perch Nannoperca oxleyana. Page(s) 97-117. (Arthington, A.H. & J.M. Hughes, 1996) [Recovery Plan].
Distribution, populations structure and habitat preferences of the Oxleyan pygmy perch Nannoperca oxleyana (Whitley 1940) near Evans Head, northeastern New South Wales Page(s) 141. Hons. Thesis. (Knight, J.T. , 2000) [Hons. Thesis].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation Gambusia holbrooki (Eastern Gambusia, Mosquitofish) Part A Distribution and Ecology. A.H. Arthington, ed. Recovery Plan for the Oxleyan Pygmy Perch Nannoperca oxleyana. Page(s) 1-84. (Arthington, A.H., C.J. Thompson & J. Esdaile, 1996) [Recovery Plan].
The threat posed by pest animals to biodiversity in New South Wales (Coutts-Smith, A.J., P.S. Mahon, M. Letnic & P.O. Downey, 2007) [Management Plan].
Invasive and Other Problematic Species and Genes:Invasive and Other Problematic Species and Genes:Predation, competition, habitat degradation and/or spread of pathogens by introduced species Northern Rivers Regional Biodiversity Management Plan (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010p) [State Recovery Plan].
Invasive and Other Problematic Species and Genes:Problematic Native Species:Competition, grazing, predation and/or habitat degradation by rats The Oxleyan pygmy perch - maintaining breeding populations. Fishes of Sahul. Journal of the Australia New Guinea Fishes Association. 7(2):310-312. (Wager, R., 1992) [Journal].
Invasive and Other Problematic Species and Genes:Problematic Native Species:Psittacine Circoviral Disease Species threats data recorded on the SPRAT database between 1999-2002 (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2012i) [Database].
Distribution, populations structure and habitat preferences of the Oxleyan pygmy perch Nannoperca oxleyana (Whitley 1940) near Evans Head, northeastern New South Wales Page(s) 141. Hons. Thesis. (Knight, J.T. , 2000) [Hons. Thesis].
Natural System Modifications:Dams and Water Management/Use:Alteration of hydrological regimes and water quality Northern Rivers Regional Biodiversity Management Plan (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010p) [State Recovery Plan].
Natural System Modifications:Dams and Water Management/Use:Alteration of hydrological regimes including flooding Distribution, populations structure and habitat preferences of the Oxleyan pygmy perch Nannoperca oxleyana (Whitley 1940) near Evans Head, northeastern New South Wales Page(s) 141. Hons. Thesis. (Knight, J.T. , 2000) [Hons. Thesis].
Natural System Modifications:Fire and Fire Suppression:Inappropriate and/or changed fire regimes (frequency, timing, intensity) Northern Rivers Regional Biodiversity Management Plan (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010p) [State Recovery Plan].
Pollution:Pollution:Deterioration of water and soil quality (contamination and pollution) Northern Rivers Regional Biodiversity Management Plan (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010p) [State Recovery Plan].
Residential and Commercial Development:Housing and Urban Areas:Habitat loss, modification and fragmentation due to urban development A fish in danger Nannoperca oxleyana. Fishes of Sahul. Journal of the Australia New Guinea Fishes Association. 6(1):247-249. (Leggett, R., 1990) [Journal].
Species Stresses:Indirect Species Effects:Low fecundity, reproductive rate and/or poor recruitment Natural Temperate Grassland of the Southern Tablelands of NSW and the Australian Capital Territory in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage, 2006abj) [Internet].
Species Stresses:Indirect Species Effects:Low numbers of individuals The Action Plan For Australian Freshwater Fishes (Wager, R. & P. Jackson, 1993) [Cwlth Action Plan].

Allen, G.R. (1989a). Freshwater Fishes of Australia. Brookvale, NSW: T.F.H. Publications.

Arthington, A.H. (1996). Recovery Plan for the Oxleyan Pygmy Perch Nannoperca oxleyana. Page(s) 129. Ctr Catchment & In-stream Res. Griffith U, Qld.

Arthington, A.H. & C.J. Marshall (1993). Distribution, ecology and conservation of the Honey Blue-eye, Pseudomugil mellis, in south-eastern Queensland.:158. Ctr Catchment & In-stream Res. Griffith U, Qld. ANCA, Canberra.

Arthington, A.H. & C.J. Marshall (1996). Threatened fishes of the world: Nannoperca oxleyana Whitley, 1940 (Nannopercidae). Environmental Biology of Fishes. 46:150.

Arthington, A.H. & J.M. Hughes (1996). Part C Conservation Status of Nannoperca oxleyana and Recovery Plan. A.H. Arthington, ed. Recovery Plan for the Oxleyan Pygmy Perch Nannoperca oxleyana. Page(s) 97-117. Ctr Catchment & In-stream Res. Griffith U, Qld.

Arthington, A.H., C.J. Thompson & J. Esdaile (1996). Part A Distribution and Ecology. A.H. Arthington, ed. Recovery Plan for the Oxleyan Pygmy Perch Nannoperca oxleyana. Page(s) 1-84. Ctr Catchment & In-stream Res. Griffith U, Qld.

Australia New Guinea Fishes Association (ANGFA) Southeast Queensland Regional Group (1986). Fraser Island - freshwater habitat survey. Fishes of Sahul. 132:134-136.

Coaldrake, J.E. (1961). The Ecosystems of the Coastal "Wallum" of Southern Queensland. CSIRO Australia Bulletin. 283.

Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC) (2011i). Survey guidelines for Australia's threatened fish. EPBC Act survey guidelines 6.4 . [Online]. EPBC Act policy statement. Canberra, ACT: DSEWPAC. Available from: http://www.environment.gov.au/epbc/publications/threatened-fish.html.

Department of the Environment and Heritage (2006abi). Nannoperca oxleyana in Species Profile and Threats (SPRAT) database. [Online]. Canberra: DEH. Available from: http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=64468.

Harrison, P.H. & M.B. Howland (1998). Surveys of the aquatic ecology and options for the eradication of Gambusia mosquitofish and the remediation of Lake Kounpee, North Stradbroke Island. Centre for Coastal Management, Southern Cross University, Lismore.

Hughes, J.M., D.A. Hurwood & M.H. Ponniah (1996). Part B Population Genetics. A.H. Arthington, ed. Recovery Plan for the Oxleyan Pygmy Perch Nannoperca oxleyana. Page(s) 85-95. Ctr Catchment & In-stream Res. Griffith U, Qld.

Hughes, J.M., M.H. Ponniah, D. Hurwood, S. Chenoweth & A. Arthington (1999). Strong genetic structuring in a habitat specialist, the Oxleyan pygmy perch Nannoperca oxleyana. Heredity. 83:5-14.

Jerry, D.R., M.S. Elphinstone & P.R. Baverstock (2001). Phylogenetic relationships of Australian members of the family Percichthyidae inferred from mitochondrial 12S rRNA sequence data. Phylogenetics and Evolution. 18:335-347.

Knight, J. & A. Arthington (2008). Distribution and habitat associations of teh endangered Oxyleyan pygmy perch, Nannoperca oxleyana Whitley, in eastern Australia. Aquatic Conservation: Marine and Freshwater Ecosystem. 18:1240-1254.

Knight, J.T. (2001a). Distributional limits of the endangered Oxleyan pygmy perch Nannoperca oxleyana (Whitley 1940) in northeastern New South Wales. Unpublished report, Office of Conservation, NSW Fisheries.

Knight, J.T. (2001b). Recent observations regarding Nannoperca oxleyana near Evans Head. Unpublished report, Office of Conservation, NSW Fisheries.

Knight, J.T. (2000). Distribution, populations structure and habitat preferences of the Oxleyan pygmy perch Nannoperca oxleyana (Whitley 1940) near Evans Head, northeastern New South Wales. Page(s) 141. Hons. Thesis. Southern Cross University, Lismore. Unpublished.

Knight, J.T., T.M. Glasby & L.O Brooks (2007). A sampling protocol for the endangered freshwater fish, Oxleyan Pygmy Perch Nannoperca oxleyana Whitley. Australian Zoologist. 34:148-157.

Kuiter, R.H. & Allen, G.R. (1986). A synopsis of the Australian pygmy perches (Percichthyidae), with the description of a new species. Review fr. Aquariol. 12(4):109-116.

Kuiter, R.H., P.A. Humphries & A.H. Arthington (1996). Pygmy Perches. In: McDowall, R.M., ed. Freshwater Fishes of South-eastern Australia. Rev ed:168-175. Reed Books, Chatswood, Sydney.

Lake, J.S. (1971). Freshwater Fishes and Rivers of Australia. Page(s) 61. Melbourne: Thomas Nelson.

Lake, J.S. (1978). Australian Freshwater Fishes. Page(s) 160. Melbourne: Thomas Nelson.

Lawrence, C. (1998). 94/075 Enhancement of yabby production from Western Australian farm dams. Western Australian Marine Research Laboratories. Fisheries Research Report No 112. Perth: Fisheries Western Australia.

Leggett, R. (1990). A fish in danger Nannoperca oxleyana. Fishes of Sahul. Journal of the Australia New Guinea Fishes Association. 6(1):247-249.

Leggett, R. & J.R. Merrick (1987). Australian Native Fishes For Aquariums. Merrick, Sydney.

Llewellyn, L.C . (1980). Chapter 25 Family Kuhliidae Pigmy Perches. In: McDowall, R.M., ed. Freshwater Fishes of South-eastern Australia. First ed:153-155. Reed Books, Sydney.

McDowall, R.M. ed (1996). Freshwater Fishes of South-Eastern Australia rev. edn. Chatswood, NSW: Reed Books.

Merrick, J.R. & G.E. Schmida (1984). Australian Freshwater Fishes - Biology and Management. Netley, South Australia: Griffin Press.

NSW Department of Primary Industries (NSW DPI) (2005f). Endangered species - Oxleyan pygmy perch. [Online]. Available from: http://www.dpi.nsw.gov.au/fisheries/species-protection/conservation/what-current/endangered-species/oxleyan-pygmy-perch.

NSW Department of Primary Industries (NSW DPI) (2005j). Recovery plan for the Oxleyan pygmy perch (Nannoperca oxleyana). [Online]. Department of Environment and Conservation, NSW. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/n-oxleyana.html.

Sanger, A.C. (1978). Aspects of the ecology and evolution of the pygmy perches (Teleostei: Kuhlidae). Unpublished Honours Thesis, Department of Zoology, University of Melbourne.

Thompson, C., A. Arthington & M. Kennard (2000). Threatened Fish Profile Oxleyan Pygmy Perch Nannoperca oxleyana Whitley, 1940. ASFB Newsletter. 30(1):31-32.

Wager, R. (1992). The Oxleyan pygmy perch - maintaining breeding populations. Fishes of Sahul. Journal of the Australia New Guinea Fishes Association. 7(2):310-312.

Wager, R. & P. Jackson (1993). The Action Plan For Australian Freshwater Fishes. Canberra, ACT: Australian Nature Conservation Agency.

Woods, K. & T. Marsden (2004). Valentines Creek Fisheries Survey. Queensland Department of Primary Industries and Fisheries.

Wootton, R.J. (1992). Fish Ecology. Chapman and Hall,: New York.

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This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.

Citation: Department of the Environment (2014). Nannoperca oxleyana in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Tue, 22 Jul 2014 21:25:37 +1000.