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 Vulnerable|
|Listing and Conservation Advices||
Commonwealth Listing Advice on Nannatherina balstoni (Threatened Species Scientific Committee, 2006dy) [Listing Advice].
Commonwealth Conservation Advice on Nannatherina balstoni (Threatened Species Scientific Committee, 2008yc) [Conservation Advice].
|Recovery Plan Decision||
Recovery Plan not required, included on the Not Commenced List (1/11/2009).
|Adopted/Made Recovery Plans|
|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
Inclusion of species in the list of threatened species under section 178 of the Environment Protection and Biodiversity Conservation Act 1999 (50) (10/11/2006) (Commonwealth of Australia, 2006c) [Legislative Instrument].
|State Listing Status||
|Scientific name||Nannatherina balstoni |
|Species author||Regan, 1906|
This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.
Scientific name: Nannatherina balstoni
Common name: Balston's Pygmy Perch
Other common name: King River Perchlet
Balston's Pygmy Perch is a small freshwater fish that grows to a maximum length of around 90 mm (commonly 60 mm). The total length of this species at one year of age (when sexually mature) averages 60 mm for males and 63 mm for females (Morgan et al. 1995). This species is brownish dorsally and silver below, usually with a prominent brown mid-lateral stripe and a series of vertical brown bars on sides giving a cross-hatched pattern (Allen et al. 2002).
Historically, Balston's Pygmy Perch had a distribution that ranged from Moore River (approximately 75 km north of Perth), in the north, to Two Peoples Bay (Goodga River near Albany, approximately 400 km south-east of Perth), in the south, and the Collie River (approximately 150 km south of Perth), to the east (Allen et al. 2002; Morgan et al. 1995, 1998).
Balston's Pygmy Perch has been lost from the northern half of its range, including the Moore River (Morgan et al. 2000), and is extremely rare or lost from many other rivers of the south-west including Blackwood River, Frankland River, Margaret River and King River (Morgan et al. 2002). It is also likely that the species has been lost from rivers and also in many lakes on the Swan Coastal Plain south of Perth, although historical records are largely absent from the region. It is now regarded as the rarest of all the endemic freshwater fishes of south-west Australia (Morgan et al. 1995).
The streams that Balston's Pygmy Perch occupy cover an area of 2000 km². The species has been captured in low numbers in major rivers, including Scott, Donnelly, Shannon, Gardner, Deep, Kent and Denmark Rivers, and lakes, including Quitjup, Smith, Doggerup, Maringup and Moates Lakes (Morgan et al. 1995). It has also been found in Bokanup and Mulgarnup Swamps, Kulunilup Lake and Lake Unicup in the Lake Muir and Unicup catchments (Storey 1998).
The species' distribution is fragmented. There are a number of extant populations that still occur over an area of 2000 km² and within a number of river systems, however these populations are restricted to only a few streams within the river systems (Allen et al. 1994).
The freshwater fishes of south-west Australia have been well surveyed in recent years. For example, almost 70 sites were surveyed in the Moore River and its tributaries and 151 sites within the Blackwood River catchment (Morgan 2005d). Eight sites on the Margaret River were surveyed in March 2003 by electrofishing, seine and gill netting, and a visual diving survey to assess fish fauna (Morgan & Beatty 2003). Fifteen wetlands were surveyed by Storey (1998) in the Lake Muir/Lake Unicup catchments on three occasions with sweep netting, rotenone and trapping, and occasionally seine netting in the larger, more open wetlands where sandy beaches were present. The considerable sampling effort suggests that the known disjunct distribution and low population sizes are an accurate representation of the current status of the species.
The species total population size is currently unknown, but there are likely to be < 1000 mature fish in each river system, suggesting that there the total population size is < 12 000 mature individuals (Morgan 2005d).
Balston's Pygmy Perch occurs in a number of highly fragmented, smaller subpopulations, which are confined to smaller streams within the major river systems of south-west Western Australia (Allen et al. 1994). The subpopulations occur within the Scott, Donnelly, Gardner, Shannon, Deep, Kent and Denmark Rivers, Lake Quitjup, Lake Muir, Doggerup Creek, Broke Inlet and Two Peoples Bay Watersheds (Morgan et al. 1998; Storey 1998). These twelve river systems are considered subpopulations.
The loss of populations from all rivers between, and including, the Moore and Margaret Rivers, represents a loss of approximately 50% of Balston's Pygmy Perch populations. Populations have become severely fragmented or lost from many of the rivers within their current distribution, e.g. Blackwood River (Morgan et al. 2003), Margaret River (Morgan & Beatty 2003), Moore River (Morgan et al. 2000) and all rivers where the species persists are occupied by feral fishes that are known to predate upon Balston's Pygmy Perch (Morgan 2005d). The trend towards population decline is therefore likely to continue in the future, due to further loss of habitat through predation by introduced species, salinisation and their low salt tolerance, damming, eutrophication and dewatering of habitat (Morgan 2005d).
It is unknown if the species undergoes extreme natural fluctuations. Balston's Pygmy Perch generally die after spawning in their first year, however, individuals have been recorded, in the wild, living to three years of age (Morgan et al. 1995). The short lifespan of this species makes it vulnerable if juvenile recruitment is low.
No cross breeding has been recorded for this species.
Many of the populations of Balston's Pygmy Perch occur within reserve systems, particularly within the Mount Frankland, Mt Roe-Mt Lindsay, D'Entrecasteaux and Shannon National Parks; from Two Peoples Bay and Lake Muir Nature Reserves; from the Hay, Rapids and Deep State Forest Blocks, and from roadside reserves (i.e. roadside ponds) in the Shire of Nannup (WA CALM 2005a). None are actively managed for the species.
Balston's Pygmy Perch inhabits acidic, tannin-stained freshwater pools, streams and lakes in peat flats within 30 km of the coast of south-west Western Australia, preferring shallow water, and commonly associated with tall sedge thickets and inundated riparian vegetation (Allen et al. 2002; Morgan et al. 1998).
Balston's Pygmy Perch is typically found in freshwater with a pH range of 3.06.5 and seasonally fluctuating temperatures of 1130 °C. It is typically found amongst inundated riparian vegetation where it is thought to feed and spawn, though adults are also found in open water. Larvae tend to be confined to shallow water < 10 cm deep amongst the flooded riparian vegetation, and as the larvae increase in size they gradually move to deeper waters (Morgan et al. 1995).
The very dry summers characteristic of south-west Western Australia result in many of the pools in which Balston's Pygmy Perch occur becoming very low, or even dry, in the later summer and autumn (Berra & Allen 1989). The species does not appear to have any adaptations to withstand desiccation, relying on their ability to recolonise these areas when water flow resumes (Morgan et al. 1995).
This species is not currently associated with a threatened ecological community, however, Western Trout Minnow (Galaxias truttaceus hesperius), listed as critically endangered under the EPBC Act, occurs in a similar area.
Balston's Pygmy Perch reach sexual maturity at the end of their first year, and, at this time, total length of individuals is about 60 mm for males and 63 mm for females (Morgan et al. 1995). Life expectancy for this species is between one and three years of age (Morgan et al. 1995).
A two-year study of the biology of the species, based upon monthly sampling, demonstrated that the life-cycle is typically one-year. The species breeds during winter (spawning occurs from June through to September with a peak in mid-July to early August when water levels are at their maximum) at the end of their first year of life, and then die shortly after spawning (Morgan et al. 1995). Females lay between 500 and 1600 eggs each (Morgan et al. 1995).
Early winter spawning allows larval and juvenile of this species to utilise the abundant zooplankton food resource in winter and spring, in turn enabling rapid growth and reducing the likelihood of competition for food resources with other sympatric species of endemic freshwater fish, which continue to feed on aquatic and benthic fauna over the summer (Morgan et al. 1995).
The diet of adult Balston's Pygmy Perch (> 25 mm) consists primarily of terrestrial insects (predominantly arachnids, adults of hymenopterans, coleopterans and dipterans) in all seasons (Morgan et al. 1995). Zooplankton (predominantly Cladocera, but also Copepoda, Ostracoda and Diptera larvae) have been identified as the food source of Balston's Pygmy Perch in the larval stage (< 15 mm), while small juveniles (1525 mm) consumed Cladocera, but also a wider range of aquatic organisms and some terrestrial fauna, including Cladocera, Ostracoda, Diptera larvae in winter and calanoid Copepoda in spring. The species is thought to feed amongst inundated riparian vegetation, and larvae are typically found feeding in very shallow water (< 10 cm), gradually moving into deeper water as they increase in size (Morgan et al. 1998).
Larvae are typically found in very shallow water (< 10 cm) and gradually move into deeper water as they increase in size, and adults may also be found in open water (Morgan et al. 1998).
Maturing fish are able to spread rapidly away from the riparian vegetation associated with spawning when water levels overflow after winter rainfall (Morgan et al. 1995).
Balston's Pygmy Perch is found with its closest relative Edelia vittata at some locations, but is usually less abundant, and has a prominent brown mid-lateral strips and a series of vertical brown bars on the sides, giving a cross-hatched pattern (Allen et al. 2002).
Balston's Pygmy Perch adults have been collected using a seine net consisting of two 4 m long wings and a 1.5 m wide pocket, each made of 3 mm mesh, and with a depth of 1.5 m (Morgan et al. 1995). Larvae were sampled using a conical 100 micrometre mesh plankton net, a 1 mm sweep net and larval fish light traps (Kilgore & Morgan 1993). Sweep netting of the marginal and emergent vegetation has been used, with 250 micrometre and 1 mm mesh aperture dip nets, rotenone (Derris Root), fish traps consisting of mesh or plastic covered funnel traps baited with cat biscuits, and seine netting in larger, more open wetlands, to catch a variety of freshwater fish in wetlands in the Lake Muir/Lake Unicup catchments (Storey 1998).
Balston's Pygmy Perch is now confined to smaller streams within the major river systems of south-west Western Australia (Allen et al. 1994). This range contraction is suspected to be due to the extensive loss of suitable habitat as a result of urban and rural development (Morgan et al. 2002). Changed hydrology conditions (salinity), alteration of drainage systems and the introduction of introduced fish species has also impacted on the distribution and range of this species.
Salinisation is is a primary cause of Balston's Pygmy Perch habitat contraction. For example, much of the main channel of Moore River is salt-affected as a result of large scale land clearing in the area. During surveys of 151 sites within the highly salt-affected Blackwood River catchment, Balston's Pygmy Perch was recorded at a single location characterised by low salinity levels (Morgan et al. 1998; Morgan et al. 2003). Many of the larger rivers of south-west Australia that encompassed the former range of Balston's Pygmy Perch have become salinised and the species is now restricted to small tributaries, headwater streams and lakes that remain fresh and are largely undisturbed. The species has only ever been recorded in fresh water (generally < 2 ppt), suggesting that its salinity tolerance is low.
The Margaret River represents one of the few river systems in south-west Australia that has not become salinised due to widescale land clearing (Morgan et al. 2002) and has retained much of the natural riparian and fringing vegetation (Morgan & Beatty 2003). Salinity levels in March 2003 were very low, ranging from 0.20.5 ppt (Morgan & Beatty 2003). Balston's Pygmy Perch were captured at only two of the eight sites above Canebreak Pool in the upper reaches of the river.
Habitat degradation is likely to have occurred through the construction of water points for fire fighting, road maintenance, mineral sand exploration and mining, groundwater extraction, and agricultural and forestry practices in the upper areas of catchments, leading to changes to river inflow, salinisation, siltation and eutrophication (Morgan et al. 1996). The 'fresh' tributaries of the Moore River are degraded as a result of the incursion into the streams by livestock (rendering many of them eutrophic and silted) and increased temperatures exacerbated by the subsequent loss of riparian vegetation.
Altered Drainage Systems
The majority of the Swan Coastal Plain, between Moore River and Margaret River, is now a network of drains that were constructed to mitigate flooding and allow for uninterrupted agriculture (Morgan & Beatty 2004). Associated agriculture and encroachment of the Perth Metropolitan Area has lead to the contraction of suitable habitat as waters are over drawn or eutrophication occurs in associated rivers.
The introduced Mosquitofish (Gambusia holbrooki) is widespread in Western Australia and is a known aggressor of south-west Australia's small endemic fishes, often nipping the entire caudal (tail) fin of its prey (Gill et al. 1999; Morgan et al. 1995; Morgan & Beatty 2003). This species represented over 50% of captures in the Blackwood River and has contributed to 93% of the total fish captures in Margaret River (Morgan & Beatty 2003). Mosquitofish have been shown to cause death in Balston's Pygmy Perch closest Western Australia relative, the Western Pygmy Perch (Edelia vittata) (Gill et al. 1999). Balston's Pygmy Perch is a surface feeder, is small in size, has a short life-cycle and occupies a similar niche to Mosquitofish, making this species vulnerable to competition, attack and ultimately population decline (Morgan et al. 1995, Gill et al. 1999). Other feral species throughout much of the range of Balston's Pygmy Perch include the piscivorous Redfin Perch (Perca fluviatilis), Rainbow Trout (Oncorhynchus mykiss) and Brown Trout (Salmo trutta) (Morgan et al. 1996).
Balston's Pygmy Perch has only been captured on two occasions with feral fishes. Mosquitofish was introduced into one of the uppermost upstream pools of the Margaret River in 2003, which had previously been regarded as free from introduced fishes (Morgan et al. 1998; Morgan & Beatty 2003). The infestation of approximately 35 individuals (thought to be the product of a single pregnant female) was eradicated (Morgan & Beatty 2003).
The Department of Fisheries have proposed to introduce three other native fish from the Murray-Darling Basin into river systems within Western Australia for the purposes of recreational stocking, domestic stocking, and commercial and non-commercial aquaculture (Department of Fisheries 2003). The species that are proposed for introduction include Golden Perch (Macquaria ambigua), Murray Cod (Maccullochella peelii) and Australian Bass (Macquaria novemaculeata). All three species are top-order predators, utilising a diversity of prey species, which includes fish, birds, mammals, amphibians, aquatic and terrestrial insects and crustaceans (Department of Fisheries 2003). Their impact upon native fish species, such as Balston's Pygmy Perch, is unknown.
The vulnerability of Balston's Pygmy Perch to population decline is compounded by their short life-cycle (one-year), low fecundities, single breeding event, low population sizes (predict < 1000 mature individuals per river system), predation from feral species (evidenced by lack of co-occurrence) and an inability to tolerate marginally saline or eutrophic waters (characteristic of the larger rivers and wetlands of south-west Australia, including those on the Swan Coastal Plain) (Morgan 2005d).
A report to the Western Australian Water and Rivers Commission (Morgan et al. 1996) regarded the most important conservation action as ensuring that the small pools, shallow areas, and riparian vegetation associated with the peat flats in which the species still occur in south-western Western Australia, are conserved. Carefully monitoring of the position of any new water points, roads, and other developments in the area was recommended. The need to introduce non-endemic species into appropriate water bodies only was highlighted.
A report prepared for the Western Australian Department of Conservation and Land Management (Storey 1998) made a number of general recommendations for the future management of the Lake Muir/Lake Unicup catchment, including:
- As a general principle, discourage the introduction of exotic species.
- Apply slow release fertilisers in agricultural areas within catchments, maintaining effective buffers around wetlands, and redirect drains away from wetlands to avoid nutrient enrichment of wetlands.
- Avoid prescribed burning in buffers surrounding wetlands.
- Fence off wetlands and their buffers to limit stock access, and limit water removal to avoid altering the inundation regime of the wetland.
The life cycle, growth and diet of Balston's Pygmy Perch was examined by Morgan and colleagues (1995). The distribution of a number of freshwater fish in south-west Australia including Balston's Pygmy Perch was described by Morgan and colleagues (1996, 1998).
Balston's Pygmy Perch
The Action Plan for Australian Freshwater Fishes (Wager & Jackson 1993) does not list Balston's Pygmy Perch, however it discusses management issues for threatened freshwater fishes.
Two Peoples Bay Nature Reserve Management Plan 19952005 (Orr et al. 1995) discusses the management priorities of an area in which the species is known to occur.
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||Commonwealth Conservation Advice on Nannatherina balstoni (Threatened Species Scientific Committee, 2008yc) [Conservation Advice].|
|Biological Resource Use:Logging and Wood Harvesting:Habitat disturbance due to foresty activities||Commonwealth Conservation Advice on Nannatherina balstoni (Threatened Species Scientific Committee, 2008yc) [Conservation Advice].|
|Climate Change and Severe Weather:Sea level rise:Inundation associated with climate change||Inundation study (Environmental Resources Information Network, 2007) [Database].|
|Ecosystem/Community Stresses:Ecosystem Degradation:Decline in habitat quality||Commonwealth Conservation Advice on Nannatherina balstoni (Threatened Species Scientific Committee, 2008yc) [Conservation Advice].|
|Energy Production and Mining:Mining and Quarrying:Habitat destruction, disturbance and/or modification due to mining activities|
|Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation||Gambusia holbrooki (Eastern Gambusia, Mosquitofish)|
|Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation||Oncorhynchus mykiss (Rainbow Trout)|
|Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation||Perca fluviatilis (Redfin, Redfin Perch)|
|Salmo trutta (Brown Trout)|
|Invasive and Other Problematic Species and Genes:Problematic Native Species:Competition, predation and/or habitat degradation by fish|
|Natural System Modifications:Dams and Water Management/Use:Alteration of hydrological regimes and water quality|
|Natural System Modifications:Dams and Water Management/Use:Extraction of ground water|
Allen, G., I. Potter & R. Lenanton (1994). Proposed addition deletion or change to the schedules of declared threatened or specially protected fauna or the reserve list Nannatherina balstoni. Perth: Department of Conservation and Land Management.
Allen, G.R., S.H. Midgley & M. Allen (2002). Field Guide to Freshwater Fishes of Australia. Perth: Western Australian Museum.
Berra, T.M. & G.R. Allen (1989). Clarification of the differences between Galaxiella nigrostriata (Shipway, 1953) and Galaxiella munda (McDowall, 1978) (Pisces: Galaxiidae) from Western Australia. Records of the Western Australian Museum. 14(3):293-297.
Department of Fisheries (2003). The Translocation of Golden Perch, Murray Cod and Australian Bass, into and within Western Australia, for the purposes of recreational stocking, domestic stocking and commercial and non-commercial aquaculture. Fisheries Management Paper No. 174. Perth: Department of Fisheries.
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.
Gill, H.S., S.J. Hambleton & D.L. Morgan (1999). Is Gambusia holbrooki a major threat to the native freshwater fishes of south-western Australia?. In: Seret, B. & J.Y. Sire, eds. Proceedings 5th Indo-Pacific Fish Conference, Noumea, 3-8 November 1997. Page(s) 79-87. Paris: Societe Francaise d'Ichtyologie et Institut de Recherche pour le Development.
Kilgore, K.J. & D. Morgan (1993). Easily constructed light trap helps scientists collect larval fishes in wetlands. The Wetlands Research Program Bulletin. 3:1-4.
Morgan, D. (2005d). Nomination form for listing changing the status, or delisting a native species under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) Nannatherina balstoni.
Morgan, D. & S. Beatty (2003). Fish fauna of Margaret River Western Australia. Report to the Margaret River Regional Environment Centre.
Morgan, D. & S. Beatty (2004). Fish fauna of the Vasse River and the colonisation by feral Goldfish (Carassius auratus). Perth: Centre for Fish and Fisheries Research, Murdoch University.
Morgan, D., H. Gill & I. Potter (1996). The distribution of freshwater fish in the south-western corner of Australia - Report to Water and Rivers Commission. Perth: Water and Rivers Commission.
Morgan, D.L., D.C. Thorburn & H.S. Gill (2003). Salinisation of south-western Western Australian rivers and the implications for the inland fish fauna - the Blackwood River, a case study. Pacific Conservation Biology. 9:161-171.
Morgan, D.L., H.S. Gill & I.C. Potter (1995). Life cycle, growth and diet of Balston's pygmy perch in its natural habitat of acidic pools in south-western Australia. Journal of Fish Biology. 47:808-825.
Morgan, D.L., H.S. Gill & I.C. Potter (1998). Distribution, identification and biology of freshwater fishes in south-western Australia. Records of the Western Australian Museum. Supplement No. 56. Perth: Western Australian Museum.
Morgan, D.L., H.S. Gill & I.C. Potter (2000). Age composition, growth and reproductive biology of the salamanderfish Lepidogalaxias salamandroides: a re-examination. Environmental Biology of Fishes. 57:191-204.
Morgan, D.L., S.J. Hambleton, H.S. Gill & S.J. Beatty (2002). Distribution, biology and likely impacts of the introduced redfin perch (Perca fluviatilis) (Percidae) in Western Australia. Marine & Freshwater Research. 53:1211-1221.
Orr, K., A. Danks & K. Gillen (1995). Two Peoples Nature Reserve Management Plan 1995-2005. Perth: Department of Conservation and Land Management for National Parks and Nature Conservation Agency.
Storey, A.W. (1998). Assessment of the nature conservation values of the Byenup-Muir peat swamp system, southwestern Australia: physiochemistry, aquatic macroinvertebrates and fishes. Perth: Report prepared for Department of Conservation and Land Management.
Wager, R. & P. Jackson (1993). The Action Plan For Australian Freshwater Fishes. Canberra, ACT: Australian Nature Conservation Agency.
Western Australia Department of Conservation and Land Management (WA CALM) (2005a). Records held in CALM's Fauna Database and rare/priority fauna files. Perth, Western Australia: WA CALM.
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). Nannatherina balstoni in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Tue, 22 Apr 2014 00:16:10 +1000.