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Oxleyan Pygmy Perch (Nannoperca oxleyana)

The Oxleyan pygmy perch is a very small, endangered freshwater fish restricted mainly to acidic, nutrient-poor wallum waters in coastal Queensland and northern New South Wales. On development sites, clearing, drainage, sediment, altered water quality, road crossings and loss of aquatic or riparian cover can damage occupied habitat or interrupt movement between waterbodies.

Conservation status

Commonwealth, EPBC Act 1999: Endangered.

Queensland, Nature Conservation Act 1992: Endangered.

Breeding season

The species can breed through much of the warmer part of the year. Timing varies with water temperature and day length, and local abundance may also change after recruitment, floods and drying events.

Timing is based on records from across Queensland and New South Wales. Local conditions, water temperature, rainfall and hydrology can shift breeding and movement activity.

  • Breeding: Spawning begins around September, with a peak from October to December. Fish develop stronger breeding colouration and lay adhesive eggs on vegetation or substrate.
  • Breeding and young: A second peak is reported from February to April. Eggs hatch within about 2 to 4 days depending on conditions, and larvae begin feeding shortly after hatching.
  • Movement and recruitment: Floods and high-flow events may transport fish within connected drainages. Surveys indicate that abundance can vary between years and sites, and young fish may occur in small groups after recruitment.
  • Highest clearing risk: Disturbance is most likely to harm the species during the September to May breeding period, especially during the October to December and February to April peaks, when eggs, larvae and spawning adults may be present. Late autumn and winter are preferred for surveys to reduce disturbance to breeding fish and habitat, but occupied wetlands remain sensitive year round.

Identification

This is a very small, laterally compressed freshwater fish. It is secretive and can be missed in suitable habitat, so identification should be confirmed by an experienced freshwater fish ecologist where possible.

Adults are usually light brown to olive, darker on the back and paler on the sides, with three to four patchy dark brown bars running from the head towards the tail. A conspicuous round dark spot with an orange margin occurs at the base of the caudal fin, and a blue ring surrounds the eye.

The dorsal fin is deeply notched and the species has no lateral line. The mouth is small and reaches to about below the pupil. The tail is square or truncate, rather than rounded.

Common length: About 35 to 45 mm

Maximum recorded length: About 60 mm

Body pattern: Three to four patchy dark bars and a dark caudal-fin-base spot with an orange margin

Identification: Breeding colour

During breeding, males develop stronger red and brown colouration, with darker or jet-black pelvic fins and more intense colour on the body and other fins. Females show a similar but less intense change, and their pelvic fins remain transparent.

Colour can vary with breeding condition, so it should be used with body shape, fin structure, markings and habitat rather than as the only identification feature.

Identification: Similar small fishes and field detection

The species can be confused with other pygmy perches and small perch-like fish, particularly juveniles. Useful field characters are the deeply notched dorsal fin, blue eye ring, small mouth, absent lateral line, patchy bars and orange-rimmed dark spot at the caudal fin base.

It is generally found alone, in pairs or in small groups of younger fish rather than in large schools. Individuals are mobile and evasive, and dip-netting alone can miss them. Small collapsible traps and backpack electrofishing are recommended methods for suitable waterbodies, with handling kept brief and fish held in water.

Typical social observation: Alone or in pairs; younger fish may occur in groups of three or four

Trap water depth: At least 20 cm for small collapsible traps

Recommended survey timing: Late autumn and winter are preferred where possible, to reduce disturbance to breeding fish and breeding habitat

  • Treat any small perch-like fish from acidic wallum water as a potential Oxleyan pygmy perch until it has been checked.
  • Avoid disturbing dense aquatic vegetation, leaf litter and undercut banks during searches.
  • Use wet hands and minimise handling because the scales are easily lost and the fish are sensitive to stress.

Distribution: Queensland

The species has a restricted, discontinuous range along approximately 534 km of coastal eastern Australia. It occurs in southern Queensland and northern New South Wales, including several sand islands, with a major gap of about 250 km separating northern and southern subpopulations.

Queensland records extend from Coongul Creek on K'gari, formerly Fraser Island, south through the Mary, Noosa and Maroochy catchments and associated coastal catchments. Records also occur on K'gari, Moreton Island and North Stradbroke Island.

Northern populations are generally rarer and more fragmented than southern populations. Mainland records include Coondoo and Tiana Creeks, Noosa River tributaries, Marcus Creek, Blue Gum Creek and Mellum Creek, while island records include Rocky, Bogimbah, Woralie, Spitfire, Warrajamba, Blue Lagoon, Ben Ewa, Craven, Tempest, 18 Mile Swamp and Little Canalpin Creek.

Northern range limit: Coongul Creek, K'gari, about 25°16'S, 153°09'E

Queensland subpopulations: Small, isolated populations across the Mary, Noosa and Maroochy catchments, coastal catchments, K'gari, Moreton Island and North Stradbroke Island

Distribution: New South Wales

New South Wales populations occur in coastal lowlands from the Richmond and Clarence catchments south to the Wooli area. Documented areas include Broadwater and Bundjalung National Parks, the Evans Head area, the Esk River subcatchment, Angourie, Wooloweyah and the Wooli and Minnie Water areas.

The southern subpopulation has been recorded in 86 waterbodies within 67 permanently connected drainage systems across eight subcatchments of the Richmond and Clarence catchments. Some populations extend about 100 km inland.

Southern range limit: Tick Gate Swamp near Wooli, about 29°54'S, 153°15'E

Known NSW strongholds: The Evans Head and South Evans Head area, Broadwater and Bundjalung National Parks, and the Wooli and Minnie Water area

Historical range loss: Historic localities at places including Beerwah, Noosa, Maryborough, Bookram Creek and Cassons Creek no longer exist or no longer support confirmed populations

Distribution: Population size and trend

A national estimate of mature individuals is not provided in the supplied documents. Abundance is usually low and varies markedly between waterbodies and between survey years. The species has been absent from some sites where it was previously recorded, and routine NSW surveys from 2008 to 2012 suggested declining abundance at most sites.

Less than 20 percent of suitable waterbodies surveyed in NSW contained the species. A survey in the Esk River catchment recorded about 100 individuals at one site, representing 55 percent of the fish catch there, while other sites in the same drainage had about 3 percent of the catch.

National mature population: Not quantified in the supplied documents

NSW suitable waterbodies occupied: Less than 20 percent in the cited survey

Example local abundance: About 100 fish at one Esk River catchment site, compared with about 3 percent of the catch at some other sites

Habitat: Waterbodies and water quality

Oxleyan pygmy perch is primarily a fish of coastal wallum, where sandy substrates, acidic water and low nutrient availability support heathland wetlands and slow-flowing freshwater systems. It can also occur in modified ponds, dams and some waters outside typical wallum vegetation when suitable cover and water quality remain.

Core habitat includes slow-flowing pools and backwaters of river channels and tributaries, swampy drainages, lakes, ponds and dams. Water is generally fresh, low in conductivity and acidic, ranging from clear water at about pH 6 to 6.5 to darkly stained water at about pH 4 to 6.

The older recovery material records a broader range, including pH greater than 3 and less than 7, with a mean pH of 4.39 across 82 NSW localities. Conductivity was usually low, with a mean of 171 microsiemens per centimetre and a reported range of 90 to 830, apart from one estuarine outlier of 8860.

Typical water movement: Still to slow flowing

Typical pH: About 4 to 6.5, with recorded sites ranging from 3.32 to 6.96 in NSW data

Typical conductivity: Low, often below 250 microsiemens per centimetre

Recorded water temperature range: 11.7 to 29.7°C in NSW locality data

Habitat: Vegetation and structure

Wallum habitat is usually associated with Banksia-dominated heath on siliceous, quartz-rich sands. Aquatic vegetation can include emergent and submerged sedges and rushes, water lilies, bladderworts, mosses and algae.

The species is closely associated with dense aquatic cover, steep or undercut banks, semi-submerged branches, fine rootlets from riparian plants, leaf litter and snags. Surveys and site assessments should map these features rather than assessing only the open-water area.

Preferred in-stream cover: About 60 to 80 percent at sites reported in the recovery material

Core substrate setting: Sandy, siliceous coastal lowlands

  • Map all connected pools, backwaters, swamps, drains, lakes and ponds within and downstream of the work area.
  • Record aquatic plant beds, undercut banks, root mats, leaf litter, snags and riparian vegetation as potential habitat features.
  • Retain shaded or vegetated bank edges and avoid unnecessary entry into shallow, plant-filled water.

Habitat: Climate and elevation

The supplied documents describe coastal lowlands and do not provide a species-specific elevation limit. Wallum country is associated with annual rainfall of about 1016 to 1778 mm. Southern NSW records can extend about 100 km inland, but the species remains associated with sandy coastal drainage systems and wetlands.

Foraging habitat: Diet

Oxleyan pygmy perch is a small carnivorous fish that feeds within dense aquatic vegetation and along sheltered margins. Adults commonly forage alone or in pairs, while younger fish may forage in small groups.

Recorded prey include zooplankton, aquatic insects, atyid shrimps, terrestrial arthropods and flying aquatic insects. Larvae feed on rotifers and protozoans, while larger fish take copepods, cladocerans, shrimps and aquatic insects, especially chironomid midges.

Gut contents from fish sampled in the Noosa River and Spitfire Creek comprised about 31 percent zooplankton, 23 percent aquatic insects, 22 percent atyid shrimps, 3 percent terrestrial arthropods and 2 percent flying aquatic insects. Other recovery material also records diatoms and filamentous algae in the diet.

Main prey groups: Zooplankton, aquatic insects and atyid shrimps

Recorded gut-content proportions: Zooplankton 31 percent, aquatic insects 23 percent, atyid shrimps 22 percent

Prey size: Generally less than 5 to 6 mm

Foraging habitat: Foraging sites and behaviour

Adults forage along the stems of aquatic plants, often alone or in pairs. Younger fish forage in groups of three or four. Dense plants provide feeding surfaces and shelter from birds and larger aquatic predators.

The fish generally occupies roughly the lower 70 percent of the water column and favours still or slow-flowing water. No fixed foraging distance or home range is given in the supplied documents.

  • Retain aquatic plant beds, leaf litter, fine rootlets and woody debris that support prey and provide cover.
  • Prevent sediment, nutrient enrichment and toxic contamination from entering feeding areas.
  • Assess connected upstream and downstream habitats because fish can move within drainage systems and may be redistributed during floods.

Breeding habitat: Breeding biology

Breeding occurs over an extended warm-season period in sheltered water containing submerged plants or other firm spawning surfaces. Eggs are adhesive and remain attached near the bottom, so disturbance to aquatic vegetation and substrate can directly affect spawning sites.

Breeding season: September to May

Peak spawning periods: October to December, with another peak reported from February to April

Spawning trigger: Water temperatures above 20°C are reported to induce spawning; another study recorded spawning at mean temperatures of at least 16.6°C with day length of at least 10.7 hours

Spawning pattern: Serial spawning, with a few eggs released regularly over several days

Eggs: Adhesive and demersal, attaching to aquatic vegetation or substrate

Hatching: About 3 to 4 days in field and recovery information; about 2 days at 25°C in aquarium material

First feeding: About 2 days after hatching in the recovery material, or 5 days after hatching in aquarium observations

Age at maturity: About 8 months for females and 18 months for males in the wild; 4 to 5 months in aquaria

Length at maturity: Reported minimums of about 19 to 23 mm, with other wild measurements of about 24 to 26 mm for males and 28 to 30 mm for females

Fecundity: Reported estimates include 225 to 270 eggs per fish and about 7.8 eggs per female per day in captive batches

Lifespan: About 6.5 years in the wild and 6 years in aquaria

Breeding habitat: Breeding habitat features

Spawning has been observed in association with submerged artificial plant-like substrate in aquaria, and field habitat includes dense emergent or submerged plants, leaf litter, snags and sheltered margins. These features provide attachment surfaces for eggs and reduce exposure to flow and predators.

Breeding habitat should be treated as more than the wetted channel. Riparian roots, undercut banks, shallow vegetated margins and connected upstream refuge areas can support adults, eggs and juveniles.

  • Avoid clearing, dredging, dewatering, sediment release and heavy machinery access to occupied pools and vegetated margins during the September to May breeding period where practicable.
  • Keep aquatic vegetation and stable spawning substrates in place.
  • Prevent sudden changes in water temperature, flow, acidity and conductivity during works.

Sheltering habitat: Cover used by fish

The species does not construct nests, burrows or hollows. Shelter is provided by aquatic and riparian structure within the waterbody, particularly dense plants, rootlets, leaf litter, snags and undercut banks.

Preferred cover includes beds of emergent and submerged sedges and rushes, water lilies, bladderworts, mosses and algae. Fish also use leaf litter beds, woody debris, steep or undercut banks and fine riparian rootlets extending into the water.

Plant beds provide shelter from surface predators such as birds and aquatic predators such as eels and larger fish. They may also reduce the effect of short high-flow events that could displace small fish downstream.

Reported habitat cover: About 60 to 80 percent in-stream cover at occupied sites

Water depth for small collapsible traps: At least 20 cm

  • Retain continuous aquatic plant beds and submerged root structure through and beside the work area.
  • Do not remove snags, leaf litter or undercut banks unless they have been assessed as unoccupied and removal has been approved.
  • Keep fish in water during any authorised capture, processing or relocation, and minimise handling time.

Sheltering habitat: Refuge and connectivity

Upper-catchment swamps and lakes may act as refuges or sources of breeding fish for downstream habitats. Movement and mixing appear to occur within individual drainages, while movement between isolated drainages is limited.

Floods and high-flow events may transport fish between connected waterbodies, although the importance of this process is not fully established. Barriers, culverts, drainage works and drying can therefore reduce access to refuge and breeding habitat.

  • Inspect culverts, crossings, drains and temporary water diversions for barriers to fish passage.
  • Maintain connected pools and backwaters where works affect a drainage line.
  • Include upstream and downstream wetlands, not only the construction footprint, in the habitat assessment.

Threats: Clearing and development

The main risks are loss and fragmentation of acidic coastal wetland habitat, degradation of water quality and the spread of introduced fish. Impacts can be local, but isolated populations have limited opportunities for recolonisation.

Coastal housing, roads, sand mining, agriculture, forestry and tourism have cleared, drained and fragmented wallum heath and its wetlands. Historic localities have been lost through development, and remaining populations are often small and isolated.

Clearing or filling riparian vegetation, aquatic plants, wetland margins or connected drainage habitat can remove shelter, feeding areas and spawning surfaces. Development can also increase erosion, sedimentation and nutrient inputs.

  • Delineate occupied and potential habitat before clearing or construction, including connected pools, backwaters, wetlands and downstream receiving waters.
  • Keep clearing, access tracks, stockpiles and laydown areas out of wetland margins and riparian buffers where practicable.
  • Use erosion and sediment controls suited to acidic sandy catchments, and inspect them after rainfall.

Threats: Roads, crossings and hydrology

Road crossings and drainage works can release sediment, remove aquatic and riparian cover, alter flow and obstruct movement between waterbodies. Dredging and barriers that block fish passage can damage habitat and may require specific approvals.

Drying of a waterbody can cause local loss. Floods may help move fish within connected systems, but excessive or altered flows can also displace small fish and damage vegetation.

  • Design crossings and temporary works to maintain fish passage and avoid isolating pools or wetlands.
  • Do not pump, divert or discharge water into occupied habitat without assessing effects on flow, temperature, acidity, conductivity and sediment.
  • Keep machinery, fuels, concrete washout and contaminated runoff away from waterways and wetland depressions.

Threats: Introduced fish and collection

The introduced eastern gambusia, also called the plague minnow or mosquito fish, is a major identified threat through competition and other interactions. Other introduced fish may also prey on or compete with pygmy perch, and common carp can damage aquatic vegetation in comparable pygmy perch habitats.

Unauthorised collection for aquaria can harm small populations and can compromise genetic differences between isolated drainages if fish are moved or released.

  • Prevent transfer of gambusia and other non-native fish between waterbodies through equipment, pumps, nets and water containers.
  • Do not release captured fish into another waterbody.
  • Use only authorised and appropriately permitted personnel for fish capture, handling or relocation.

Threats: Other pressures

Nutrient enrichment, toxic contaminants, sedimentation, loss of riparian vegetation and altered nutrient dynamics can reduce habitat suitability. The supplied documents do not identify a specific disease threat or provide a species-specific fire response.

Fire effects should therefore be assessed through likely impacts on riparian vegetation, ash and sediment entering water, bank stability, water quality and post-fire runoff rather than assumed from fire alone.

  • Inspect water quality and aquatic cover after major earthworks, floods, droughts, fire or pollution events.
  • Retain riparian vegetation and stabilise exposed sandy soils before rainfall.
  • Report any injured, stranded or unexpectedly captured fish through the relevant state threatened species process.

Survey methodology: 1. Select habitat and timing

Oxleyan pygmy perch surveys must target shallow, still or slow flowing freshwater habitats in coastal wallum, including swamps, creeks, lakes, ponds and dams. The species is small, secretive and easily missed, so use a combination of low impact methods and record habitat conditions as well as captures.

Map all freshwater habitats and connected drainage lines within the project area, including downstream areas that could receive sediment, altered flows or contaminated water.

Prioritise waterbodies with acidic, low conductivity water, dense aquatic vegetation, leaf litter, snags, undercut banks and submerged riparian roots.

Schedule surveys in late autumn or winter where practicable. The species breeds from September to December and may continue breeding until May, so avoid disturbing breeding habitat during this period.

Do not treat an absence from one survey as proof that the species is absent. Local abundance varies substantially and fish may be missed during dry periods or after population fluctuations.

Typical habitat: Still to slow flowing, acidic freshwater in coastal wallum and Banksia dominated heath

Known range: Approximately 534 km of coast, from K'gari in Queensland to near Wooli in northern New South Wales

Breeding period: September to April or May, with peak spawning reported from October to December

Preferred water depth for small traps: At least 20 cm

Survey methodology: 2. Backpack electrofishing

Use backpack electrofishing in wadeable creeks, wetlands, shallow lake margins and other suitable habitats, in accordance with the applicable Australian Code of Practice and state requirements.

Sample dense aquatic vegetation, sheltered margins, undercut banks, root mats, leaf litter and snags without stripping or unnecessarily disturbing the habitat.

Use electrofishing with trapping and dip netting where appropriate. Operate equipment to minimise stress, scale loss, injury and mortality.

Do not use boat based electrofishing as the default method for this species group. Obtain the required authority before any electrofishing.

Detection: Backpack electrofishing and trapping have similar detection rates for pygmy perches

Handling: Keep fish out of water for the shortest possible time and hold them in a container of site water

Survey methodology: 3. Collapsible traps and dip nets

Set small, unbaited collapsible traps for 30 to 60 minutes in suitable habitat, particularly beside aquatic vegetation, root-filled banks and other cover.

Saturate the site with unbaited traps where access and approvals allow, with traps set for at least 30 minutes as part of a standardised search.

Check traps frequently and remove fish promptly. Leave an air space in traps where overnight deployment is authorised, to reduce the risk of low oxygen and mortality.

Use dip nets only as a supplementary method because Oxleyan pygmy perch are mobile and evasive and can be easily missed.

Use fine mesh seine nets only where electrofishing is unavailable or cannot be deployed. Avoid dragging nets through littoral or submerged vegetation because seine netting can disturb habitat and has higher mortality risk.

Trap depth: At least 20 cm of water

Trap duration: 30 to 60 minutes, with at least 30 minutes for a standardised saturating search

Seine mesh: 2 to 5 mm where seining is authorised and necessary

Survey methodology: 4. Handling, identification and survey records

Handle fish with wet hands and minimal contact because scales are easily lost and the species is sensitive to handling.

Keep captured fish in site water while they are being identified, measured or photographed, and return them promptly to the capture location unless an authorised officer directs otherwise.

Record the method, trap or electrofishing effort, survey date and time, waterbody, coordinates, water depth, water level, vegetation cover, substrate, flow, pH and conductivity where measured.

Record negative results with the same detail as positive results, including the area and habitat searched and any limitations caused by access, water depth, turbidity or weather.

Adult size: Up to about 60 mm, more commonly about 35 to 45 mm

Key identification features: Small mouth, blue eye ring, deeply notched dorsal fin, and dark spot with an orange rim at the caudal fin base

Survey methodology: Minimum effort and reporting

  • Use more than one method where practicable, combining backpack electrofishing with unbaited collapsible traps and careful dip netting.
  • Survey all suitable waterbodies and connected drainage features within the impact area, and inspect habitats that may receive indirect impacts such as sediment, altered drainage or contaminated runoff.
  • Plan surveys outside the breeding period where practicable, with late autumn and winter preferred for reducing disturbance to breeding fish and habitat.
  • Obtain all state and Commonwealth permits required for electrofishing, trapping, handling and threatened species surveys before fieldwork starts.
  • Submit positive and negative survey records, capture details, photographs and coordinates to the relevant state wildlife database and to the project approval holder.
  • Report any suspected Oxleyan pygmy perch record promptly to the relevant state threatened species authority and retain the original field data with the project records.

Before habitat disturbance: Avoid and minimise

Treat every suitable wallum waterbody and connected drainage feature as potential habitat until survey evidence and approvals show otherwise. Avoid direct disturbance first, then reduce changes to water quality, flow, connectivity and aquatic cover.

  • Redesign the project to avoid swamps, creeks, lakes, ponds, dams, backwaters and slow flowing pools that contain suitable habitat.
  • Retain aquatic vegetation, leaf litter, snags, undercut banks, submerged roots and riparian vegetation around occupied and potential habitat.
  • Prevent barriers that block fish passage between connected waterbodies, including poorly designed crossings, temporary causeways and drainage controls.
  • Maintain natural drainage, low flow conditions and water levels as far as practicable, and prevent rapid dewatering of occupied or potential habitat.
  • Establish project specific no go areas and buffers around retained waterbodies and riparian margins, based on the risk of sediment, runoff, dewatering, vibration and accidental machinery entry.

Before habitat disturbance: Approvals and work planning

  • Check whether the proposed action is likely to have a significant impact on this EPBC Act listed endangered species or its habitat, and refer the action under the EPBC Act where required.
  • Obtain state permits and scientific, threatened species, fisheries, animal ethics and electrofishing approvals required for survey, capture, handling, relocation or salvage.
  • Prepare a fauna management plan that identifies suitable habitat, survey methods, exclusion areas, stop work triggers, authorised personnel, aquatic hygiene controls and incident reporting.
  • Stage clearing and earthworks so that habitat is retained until surveys, approval conditions and fauna management measures are complete.
  • Schedule in stream work outside the September to May breeding period where practicable, and avoid works during high rainfall or flow conditions that could spread sediment or contaminants.

Before habitat disturbance: Site preparation

  • Complete a pre clearance aquatic habitat survey using the approved methods before machinery enters the work area.
  • Mark retained waterbodies, drainage lines, riparian vegetation, aquatic plant beds, undercut banks and snags on plans and on the ground.
  • Install exclusion fencing and no entry markers where they can prevent machinery, spoil, fuel, concrete washout and sediment controls from entering habitat.
  • Set up clean water, dirty water and refuelling zones away from waterbodies and drainage lines.
  • Confirm the nearby retained habitat that would receive an authorised relocation, if relocation is approved, and confirm that it has suitable water levels, cover and water quality.

During habitat disturbance: Daily controls and machinery interface

A fauna spotter catcher must work as part of the construction team, with authority to pause works where fish habitat or water quality is at risk. The species is small and aquatic, so prevention of habitat damage and uncontrolled water movement is more effective than relying on capture during clearing.

  • Inspect exclusion fencing, sediment controls, pumps, crossings, screens and retained habitat before work starts each day and after substantial rain.
  • Brief operators on the mapped habitat, exclusion zones, access routes, refuelling rules and stop work triggers.
  • Keep machinery, spoil, stockpiles, concrete washout, fuels and chemicals out of waterbodies, drainage lines and riparian exclusion areas.
  • Use a spotter catcher to control machinery movements near retained aquatic habitat and to confirm that no fish habitat is being crushed, drained, blocked or filled.
  • Stop pumping or diversion if fish, aquatic vegetation, sediment or contaminated water could be drawn into equipment or discharged into retained habitat.

During habitat disturbance: Aquatic habitat and feature handling

  • Avoid removing aquatic vegetation, submerged roots, leaf litter and snags from retained habitat unless the approved method specifically requires it.
  • Treat logs and snags in or beside water as fish cover and retain them where safe and consistent with the approved design.
  • Do not use hollow bearing tree, nest box or burrow protocols as a substitute for aquatic habitat controls, because Oxleyan pygmy perch use waterbodies, aquatic vegetation, undercut banks, roots, leaf litter and snags rather than tree hollows.
  • Keep rocks and woody debris that form bank cover in place where practicable, and prevent bank collapse and sediment entry during access or crossing works.
  • Do not drain, isolate or fill a waterbody until the authorised aquatic fauna survey and any approved salvage procedure are complete.

During habitat disturbance: If a fish is found

  • Stop the activity that could harm the fish or its habitat and keep machinery, pumps and people clear of the water until the authorised fauna lead gives direction.
  • Do not catch, possess, move or release the fish unless the person and method are authorised under the relevant approvals.
  • Keep any captured fish in clean, aerated site water and handle it with wet hands and minimal contact.
  • Return the fish promptly to the capture location unless an approved relocation or salvage plan directs release into nearby retained habitat with suitable water quality and cover.
  • Send injured fish to an authorised aquatic wildlife carer, veterinarian or other approved facility, and record the advice and outcome.
  • Treat any uncertain pygmy perch identification as a potential threatened species record until confirmed by a suitably qualified person.

During habitat disturbance: Stop work and records

  • Stop work immediately for a confirmed or suspected Oxleyan pygmy perch, unexpected occupied habitat, fish mortality, dewatering, a failed sediment control, a spill or a blocked fish passage.
  • Do not restart until the fauna lead, site environmental officer and relevant approval holder have assessed the risk and documented the control measures.
  • Record the date, time, location, activity, personnel, weather, water conditions, species identification, photographs, handling, release or injury outcome and notifications.
  • Report breaches, mortality, injury, unauthorised capture and water quality incidents in accordance with approval conditions and state reporting requirements.

After habitat disturbance: Post clearance checks

Post work checks must confirm that retained habitat still functions as connected, acidic, low nutrient freshwater habitat with adequate cover. Monitoring should be scaled to the approval risk and focused on occupied sites, retained habitat and receiving waterbodies.

  • Inspect the cleared area, retained waterbodies, drainage lines, crossings and downstream receiving habitat for fish, stranded animals, sediment, erosion, spills, changed flow and damaged aquatic vegetation.
  • Check for trapped or isolated pools after dewatering, pumping, storm events and temporary access removal.
  • Remove temporary barriers and restore fish passage when the work stage is complete, unless an approved design requires a permanent structure.
  • Repair failed exclusion fencing, sediment controls, bank stabilisation and riparian protection without entering retained habitat unnecessarily.

After habitat disturbance: Monitoring and reporting

  • Monitor occupied and retained habitat using the approved combination of backpack electrofishing, unbaited traps and other authorised methods, with late autumn and winter preferred where practicable.
  • Compare post work results with the pre disturbance survey using the same methods, locations and effort so that changes in detection are interpretable.
  • Measure and report water quality, water levels, flow, aquatic vegetation, bank condition, sedimentation and fish passage at the frequency required by approvals.
  • Submit records and any confirmed impacts to the relevant state wildlife database and the Commonwealth reporting system where required by the approval.
  • Maintain a project register of captures, deaths, injuries, relocations, complaints, incidents, corrective actions and monitoring results.

After habitat disturbance: Offsets and corrective action

  • Apply any EPBC Act, state or approval based offset requirement using the approved offset calculation and conservation mechanism.
  • Do not use an offset as a substitute for avoiding occupied habitat, retaining connectivity or controlling sediment and water quality impacts.
  • Escalate corrective action if monitoring shows declining detections, loss of aquatic cover, reduced connectivity, altered acidity or conductivity, increased sedimentation or repeated fish mortality.

Rehabilitation actions: Restore habitat structure and water

Rehabilitation should recreate the quiet, low nutrient, acidic freshwater habitat and structural cover used by Oxleyan pygmy perch. The goal is functional habitat with stable water quality, connected drainage and persistent aquatic vegetation, not simply revegetated banks.

  • Reinstate natural drainage patterns and shallow slow flowing pools, backwaters, swales or wetland areas where these were disturbed and where the approved design permits.
  • Use local wallum and riparian plant material suited to the site, including native sedges, rushes, emergent plants and Banksia dominated heath vegetation where appropriate.
  • Replant riparian margins to provide undercut roots, shade, bank stability and leaf litter, while avoiding dense planting that blocks required access or changes approved flow paths.
  • Retain or reinstate submerged logs, snags, woody debris, leaf litter and root structure where they provide cover and do not create a flood or safety hazard.
  • Do not add nutrients, lime or other materials that would raise pH or alter the naturally oligotrophic and acidic condition of the habitat.

Rehabilitation actions: Connectivity, weeds and predators

  • Maintain fish passage between retained pools, swamps, lakes, creeks and connected drainage features, including through road crossings and temporary works areas.
  • Control weeds that displace native aquatic or riparian cover, using methods that prevent herbicide or disturbed sediment entering the water.
  • Prevent the introduction and spread of Gambusia holbrooki and other non native fish through fish stocking controls, clean equipment and managed water transfers.
  • Manage fire in accordance with the approved wallum habitat plan and local fire authority advice, avoiding actions that remove riparian cover, expose erodible sand or cause ash and sediment to enter occupied water.

Rehabilitation actions: Monitoring and success measures

  • Inspect rehabilitation after rainfall and at the approved monitoring intervals for bank stability, erosion, sediment, water levels, flow, pH, conductivity, aquatic vegetation and fish passage.
  • Use authorised fish surveys to assess whether Oxleyan pygmy perch return to, persist in or successfully use the rehabilitated habitat, while avoiding the September to May breeding period where practicable.
  • Set success measures for stable water quality, persistent native aquatic cover, functioning fish passage, no uncontrolled sediment input, no Gambusia introduction and detection of the species where it was present before disturbance.
  • Continue weed, erosion, predator and access controls until the success measures are met and responsibility has been formally transferred to the land manager.

Sources