Western Dwarf Galaxias (Galaxiella munda)

Conservation status

Commonwealth, EPBC Act 1999: Vulnerable.

Western Australia, Biodiversity Conservation Act 2016: Vulnerable.

Breeding season

The western dwarf galaxias has a predominantly annual life cycle, with breeding in winter and spring and breeding-age fish generally absent from surveyed waterbodies by the following March. Timing can vary with local flow, temperature and inundation.

The season pattern is based on the supplied records for the species. Local conditions, especially flow, groundwater discharge and flooding, should be checked before works begin.

• Breeding: Spawning occurs from July to October and peaks in late August. Adults may spawn more than once in a season.
• Young: Larvae occur in very shallow water among flooded riparian vegetation, then move into deeper pool water and connecting streams as they grow.
• Movement and recruitment: Growing larvae move from shallow flooded margins into deeper pools and connecting streams. No long-distance migration is reported.
• Adult decline after breeding: Individuals die shortly after breeding, and growth surveys found breeding-age fish absent from waterbodies by the following March.
• Highest clearing risk: Clearing, bank works, dewatering and disturbance are most likely to harm the species from July to October, when adults spawn and larvae occupy shallow flooded riparian vegetation. Habitat and hydrology damage can affect the species at any time.

Identification

This is a small, stocky, scaleless galaxiid with an elongated body, large eyes and a short, bluntly rounded head. Identification is most reliable when body colour, longitudinal stripes, fin shape, size and the locality are considered together.

Adults can reach approximately 60 mm total length. The back is dark brown in tannin-stained swamp water and olive-green in clearer water. The underside is silvery-white. The body is scaleless and elongated, with mostly small membranous fins and a long, rounded caudal fin.

Maximum size: Approximately 60 mm total length

Body: Elongated and scaleless, with a short, bluntly rounded head, large eyes and a small mouth

Colour: Dark brown to olive-green above and silvery-white below

Identification: Breeding colour and sex

From about June to October, adults commonly develop an orange lateral stripe between two olive-brown longitudinal bands. The orange stripe becomes a thin silver-white line after October and disappears as body colour becomes uniform by January. The source material gives maturity sizes for females and males, but does not provide reliable external features for separating the sexes outside the breeding period.

Female maturity size: Approximately 47 mm total length

Male maturity size: Approximately 43 mm total length

Breeding colour: Orange lateral stripe between two olive-brown longitudinal bands

Identification: Similar species and field signs

The western dwarf galaxias may occur with western minnow, western pygmy perch and the black-striped minnow. The black-striped minnow is morphologically similar, but generally occurs closer to the coast in floodplain habitats, while the western dwarf galaxias is usually associated with smaller creeks and pools and can occur further inland. The two species overlap only to a limited extent in seasonally connected floodplain habitat.

• Do not rely on a single colour feature because body colour changes with water clarity and tannin staining.
• Record the exact capture location, waterbody type, habitat and photographs where possible, particularly where black-striped minnows may also occur.
• No species-specific tracks, scats, calls, nests, burrows, sloughs or eyeshine are expected. Detection is by observation or capture in suitable freshwater habitat.

Distribution: National range

The species is endemic to Western Australia. Its distribution is concentrated in the south-west, with a historically isolated northern population near Gingin whose current status is uncertain.

The species is known only from Western Australia. It occurs across nine coastal catchments: Swan Coastal, Busselton Basin, Blackwood River, Donnelly River, Warren River, Shannon River, Kent River Basin, Denmark Basin and Albany Coast.

States recorded: Western Australia only

Known catchments: Nine coastal catchments

Approximate northern population location: Near Gingin, about 100 km north of Perth

Southern range: From the Vasse River and Margaret River area to Albany

• The southern population extends from the Vasse River and Margaret River area in the Busselton Basin to Albany on the south coast.
• The northern population was recorded near Gingin, about 100 km north of Perth, in tributaries of the Moore River and Swan River systems.
• The species is generally restricted to a few kilometres of smaller freshwater tributaries rather than occurring throughout entire river systems.

Distribution: Strongholds and subpopulations

Known southern sites include the upper Vasse River, upper Margaret River, groundwater-fed tributaries of the Blackwood River and fewer than 20 water systems between the Donnelly and Angove rivers. The northern population has historical records from Lennard Brook, Gingin Brook and Ellen Brook.

• Most sites are in the south-western corner of Western Australia, including catchments associated with the Warren, Shannon, Kent, Denmark and Albany areas.
• Approximately 80 to 90 percent of sites are within national parks or state forests.
• Recorded sites overlap several national parks and nature reserves, including Shannon, D'Entrecasteaux, Mount Frankland South, Lake Muir, Walpole-Nornalup, Blackwood River, Jane, Mount Roe and Mount Lindsay areas.

Distribution: Population size and trend

A national estimate of mature individuals is not provided in the supplied documents. The species is generally rare, although it can be locally abundant. Genetic sampling across 13 sites found high divergence between most sites, indicating little connectivity and making each population important for retaining genetic diversity.

Mature population estimate: Not provided

Genetic sampling: 13 sites

Threat-defined locations: Six

Northern population consequence: Loss would reduce geographic extent of occurrence by approximately 80 percent

• Recent surveys have failed to locate the species at Lennard Brook or Gingin Brook, and its current persistence in the northern population is uncertain.
• The species is assessed as Vulnerable because its distribution is restricted to six threat-defined locations, with projected or inferred declines in distribution, habitat quality, populations and mature individuals.
• Loss of the isolated northern population would reduce the species' geographic extent of occurrence by approximately 80 percent.

Habitat: Waterways and vegetation

The western dwarf galaxias occupies small, freshwater headwaters and tributaries in peat flats and adjoining forest. It needs shallow pools, flowing connections, vegetated margins and, at some sites, groundwater discharge that maintains flow and moderates water conditions.

Adults occur near riparian vegetation, including Melaleuca, and among submerged vegetation in streams. They also use open water in pools. Larvae occur in very shallow water, generally less than 10 cm deep, among flooded riparian vegetation before moving into deeper pool water and connecting streams as they grow.

• Look for small headwater streams and tributaries of flowing rivers.
• Inspect shallow pools connected to streams, particularly pools in peat flats.
• Retain riparian and emergent vegetation at stream margins and around shallow pools.
• Treat groundwater-fed tributaries and spring-fed reaches as potentially important habitat, including where surrounding surface water is seasonally saline or unreliable.

Habitat: Water conditions and physical setting

Occupied waters are acidic, with recorded pH from 3.0 to 6.0, and experience strong seasonal temperature variation from 11 to 35 degrees Celsius. The species is generally associated with low-conductivity freshwater, below 1 mS/cm or below 550 mg/L total dissolved solids.

Recorded pH: 3.0 to 6.0

Recorded temperature range: 11 to 35 degrees Celsius

Typical conductivity: Below 1 mS/cm

Typical total dissolved solids: Below 550 mg/L

• Avoid increasing salinity, sedimentation or nutrient enrichment in occupied and connected tributaries.
• Maintain surface flows and groundwater expression that support permanent or semi-permanent pools and flooded spawning margins.
• Avoid in-stream dams, gully dams, altered channels and other works that interrupt small tributary connections or change flood timing.

Habitat: Climate and elevation

The supplied documents do not provide an elevation range. The species is confined to the Mediterranean climate of south-western Western Australia and is expected to be most exposed where hotter, drier conditions reduce surface flow, groundwater recharge and water quality.

• Do not assume that a dry channel is unoccupied. Small permanent pools, hyporheic areas and groundwater-fed reaches may provide refuge during dry periods.
• Include upstream catchment works in habitat assessment because clearing, drainage, abstraction and altered runoff can affect downstream habitat.
• Consider both the local stream and connected pools when defining the area that may be affected by a project.

Foraging habitat: Food and feeding sites

The western dwarf galaxias is a generalist carnivore. It feeds in shallow freshwater streams and pools, including areas near riparian and submerged vegetation.

The diet includes terrestrial insects, microcrustaceans and insect larvae. Adults use streams, vegetated margins and open pool water, while larvae initially occupy very shallow water among flooded riparian vegetation.

Diet: Terrestrial insects, microcrustaceans and insect larvae

Foraging habitat: Headwater streams, connected pools, riparian margins, submerged vegetation and open pool water

• Keep riparian vegetation and overhanging vegetation intact where practicable because these areas support the aquatic margin and can supply terrestrial invertebrate prey.
• Prevent sediment, nutrient and chemical inputs that could reduce water quality or alter aquatic invertebrate communities.
• Search shallow pool margins, submerged vegetation and slow-flowing sections as well as the main current.

Foraging habitat: Foraging range

No home-range or daily movement distance is reported. The species is thought to occupy only a few kilometres within the smaller tributaries where it occurs, but this is a distribution pattern rather than a measured individual foraging range.

• Do not use the absence of fish from one short reach to conclude that nearby connected habitat is unused.
• Assess adjacent pools, tributaries and groundwater-fed reaches because local habitat use can change with seasonal flow and water level.
• Maintain passage between pools and streams where works could otherwise isolate feeding habitat.

Breeding habitat: Breeding biology

Breeding occurs in flooded marginal vegetation in streams, pools and lakes. Maintaining shallow inundated margins, seasonal flow and suitable water quality is important during the breeding period.

Adults spawn more than once in a breeding season. Spawning is presumed to occur among emergent peripheral vegetation in flood waters, either within streams or in inundated vegetation around pools and lakes. Eggs are approximately 1 to 1.5 mm in diameter.

Breeding season: July to October

Peak spawning: Late August

Egg size: Approximately 1 to 1.5 mm diameter

Average fecundity: Approximately 65 eggs

Maturity: About one year old

Adult survival after breeding: Individuals die shortly after breeding; one-year-class fish were absent from surveyed waterbodies by the following March

Gestation or incubation: Not stated in the supplied documents

Lifespan: Not stated; available growth surveys indicate a predominantly annual life cycle

• Avoid clearing, draining or disturbing emergent vegetation and shallow flooded margins from July to October where occupied habitat is present.
• Plan crossings, dewatering and bank works to avoid reducing the duration or extent of shallow inundation.
• Treat all connected shallow pools and seasonally flooded margins as potential breeding habitat during winter and spring.

Breeding habitat: Larval habitat

Larvae are typically found in water less than 10 cm deep among flooded riparian vegetation. As they grow, they move into deeper pool water and then into connecting streams.

• Retain shallow flooded vegetation at pool edges and stream margins.
• Avoid rapid drawdown, sediment deposition and vehicle access through shallow breeding margins.
• Inspect flooded vegetation and shallow pools before disturbing water margins during the breeding season.

Sheltering habitat: Aquatic refuges

The species has no known terrestrial den, hollow, burrow or nest. Shelter is provided by aquatic habitat, especially shallow pools, submerged vegetation, vegetated margins and groundwater-fed or hyporheic reaches.

Adults occur close to riparian vegetation and submerged vegetation, as well as in open pool water. Groundwater discharge can create hyporheic habitat that buffers temperature, supports flow and water quality, and maintains aquatic habitat and movement routes.

Known aquatic cover: Riparian vegetation, including Melaleuca, submerged vegetation and shallow pool margins

Groundwater refuge: Hyporheic zones and groundwater-fed reaches can buffer temperature and maintain flow, oxygen, productivity and movement routes

Shelter structures: No species-specific dens, hollows, burrows or nests reported

• Protect permanent and semi-permanent pools during dry periods and construction dewatering.
• Keep submerged, emergent and riparian vegetation where it forms cover at occupied sites.
• Avoid blocking or sealing groundwater discharge points and spring-fed tributaries.
• Do not assume that refuge is limited to the visible channel. Assess hyporheic and groundwater-fed areas where the project may alter flow or groundwater levels.

Sheltering habitat: Seasonal refuge requirements

During dry conditions, fish may be concentrated in remaining permanent pools and stream sections. These areas can also attract invasive fish, increasing predation pressure.

• Survey remaining pools and groundwater-fed reaches when flows are low, while avoiding unnecessary disturbance.
• Keep pools connected to suitable stream habitat where practicable.
• Control access by invasive fish to refuge pools through prevention, containment and approved management actions.

Threats: Clearing and habitat alteration

The main project risks are loss or alteration of small freshwater tributaries, reduced surface or groundwater flow, salinisation, sedimentation, invasive fish and interruption of pool and stream connections. Risks can occur upstream or outside the occupied reach because the species depends on catchment water regimes.

Land clearing, agricultural and forestry activities have contributed to salinisation, eutrophication and siltation. The species has not been found at sites surrounded by cleared agricultural land. In-stream gully dams, altered channels and other works can isolate populations and reduce their available habitat.

• Avoid clearing riparian, emergent and submerged vegetation around occupied streams, shallow pools and flooded margins.
• Keep machinery, stockpiles, spoil and sediment out of streams and pools.
• Avoid new dams, weirs, gully dams, flood-control channels and drainage changes that reduce downstream flow or alter flood timing.
• Maintain vegetated buffers and protect small tributaries, not only larger named rivers.

Threats: Hydrology, water use and climate

Reduced rainfall, drought, groundwater abstraction and surface-water use can reduce streamflow, increase salinity and remove shallow breeding habitat. Groundwater discharge is particularly important at some sites, including the northern population and parts of the Margaret and Blackwood river systems.

• Assess both surface-water and groundwater effects before approving excavation, dewatering, drainage, pumping or abstraction.
• Maintain flows that support permanent pools, shallow flooded vegetation and groundwater-fed reaches.
• Prevent saline or nutrient-rich runoff from entering occupied or connected freshwater habitat.
• Include hotter and drier conditions in the assessment of long-term flow and water-quality impacts.

Threats: Invasive fish and fragmentation

Eastern gambusia is widespread through much of the species' range and can compete with native fish and prey on eggs, larvae and juveniles. Redfin perch, rainbow trout and brown trout are also established invasive fish in south-western Western Australia. Introduced redfin perch are associated with the disappearance of fish around Big Brook Dam, and eastern gambusia has been implicated in declines in the Margaret River and the uncertain status of the northern population.

• Prevent the release or spread of non-native fish during construction, water transfers, dam works and aquatic rehabilitation.
• Inspect connected waterways for eastern gambusia and other invasive fish before moving water, equipment or aquatic material between sites.
• Avoid creating new permanent pools or altered connections that favour invasive fish.
• Use project-specific invasive fish control methods approved by the relevant Western Australian authority.

Threats: Fire, roads and disease

The supplied documents identify fire as a potential additional climate-related impact but do not provide species-specific fire thresholds. They do not identify road mortality or disease as documented primary threats. Roads, crossings and construction access can still harm habitat indirectly through sediment, altered drainage, barriers, spills and disturbance of shallow pools.

• Keep crossings narrow and prevent sediment and contaminated runoff from entering tributaries and pools.
• Do not use occupied pools or streams as wash-down, water-supply or discharge points.
• Assess fire-related loss of riparian cover, altered runoff and post-fire sediment delivery after burns near occupied habitat.
• Include disease prevention in aquatic works by cleaning and drying equipment between catchments and following current hygiene procedures.

Threats: Fragmentation and genetic loss

Genetic evidence shows high divergence between most sampled sites and little connectivity. Local extinctions can therefore remove unique genetic variation, even where other populations remain.

Genetic sampling: 13 sites

Connectivity: Little connectivity between most sites

Conservation implication: Local extinction may result in loss of unique genetic variation

• Treat all confirmed populations as important, rather than relying only on larger or more frequently occupied sites.
• Protect nearby suitable habitat that could support natural migration or carefully planned translocation.
• Avoid works that isolate small tributaries, pools or groundwater-fed reaches.

Survey methodology: 1. Habitat and records assessment

Western Dwarf Galaxias is a small freshwater fish found in shallow headwater streams, tributaries, peat flats and connected pools in south-west Western Australia. Surveys should target suitable aquatic habitat and account for the species’ small size, seasonal breeding and highly isolated populations.

Before field work, map all headwater streams, small tributaries, shallow pools, peat flats, groundwater discharge areas and associated riparian vegetation within and downstream of the project area.

Check recent and historical records, including records from nearby catchments. The species has been recorded across nine coastal catchments and may occupy only a few kilometres of smaller freshwater tributaries.

Treat all sites as important where the species may occur, because genetic differences between sites are high and connectivity is low.

Known distribution: Western Australia, from the Vasse River and Margaret River area to Albany, with an isolated northern population near Gingin

Typical water quality: Acidic water, pH 3.0 to 6.0, generally low conductivity below 1 mS/cm

Typical habitat: Shallow flowing headwater streams, tributaries, peat flats, forested areas and shallow pools connected to streams

Survey methodology: 2. Targeted aquatic fish survey

Use appropriately permitted aquatic fish survey methods suited to shallow streams and pools, such as fine-mesh seine nets, small fyke or bait traps, or electrofishing where authorised and safe for the waterway and other fauna.

Sample shallow pool margins, flooded peripheral vegetation, submerged vegetation and riparian edges. Larvae are typically found in water less than 10 cm deep among flooded riparian vegetation.

Survey during the breeding period from July to October where project timing allows. Adults and larvae may use inundated vegetation during this period.

Use trained fish ecologists who can distinguish Western Dwarf Galaxias from other small galaxiids and record the survey method, effort, water depth, water quality, habitat condition and all captured species.

Breeding period: July to October

Maximum recorded length: Approximately 60 mm total length

Larval habitat: Very shallow pool margins, generally less than 10 cm deep, among flooded riparian vegetation

Survey methodology: 3. Seasonal and repeat coverage

Plan repeat surveys where the site contains suitable habitat but the species is not detected on the first visit, particularly where water levels, seasonal flow or groundwater discharge vary.

Include surveys of permanent pools and groundwater-fed sections because these areas may retain fish during dry periods and can provide thermal and flow refuge.

Record negative results with the exact site, date, water conditions, survey effort and method. A failure to detect the species should not be treated as proof that suitable habitat is unoccupied, especially at sites where the northern population has become difficult to locate.

Survey methodology: Minimum effort and reporting

• Use a suitably qualified aquatic ecologist and obtain all permits required for fish capture, handling, electrofishing, water access and threatened species work before surveying.
• Do not apply an invented fixed number of nights, trap nights, transect kilometres or survey hours. The supplied documents do not specify a species-specific survey effort or survey guideline for Western Dwarf Galaxias.
• Survey all suitable aquatic habitat within the disturbance footprint and any connected habitat that could be affected by altered flow, groundwater use, sediment or fish movement.
• Submit confirmed records and reliable negative survey information to the relevant Western Australian wildlife or biodiversity database, with coordinates, date, observer, method, effort, photographs where suitable and voucher or genetic material only where authorised.
• Report any suspected Western Dwarf Galaxias record promptly to the project environmental officer and the relevant state authority before works continue in the affected habitat.

Before habitat disturbance: Avoid and minimise

Avoiding disturbance to occupied and suitable aquatic habitat is the first control. This species depends on shallow freshwater habitat, stable flow, groundwater inputs and connected pools, and many populations have little connectivity.

Redesign the project to avoid headwater streams, small tributaries, shallow connected pools, peat flats, riparian vegetation and groundwater discharge areas wherever practicable.

Retain streamside vegetation, submerged vegetation, flooded peripheral vegetation and the natural bed and banks of streams and pools.

Prevent changes to surface flow, groundwater expression, water depth, salinity, temperature and acidity. Groundwater discharge can maintain flow, water quality, thermal refuge and habitat in otherwise unsuitable catchments.

Maintain connections between occupied pools and streams. Do not install dams, crossings, drains, culverts or other structures that isolate habitat or change seasonal flooding without specific assessment and approval.

Before habitat disturbance: Approvals and project controls

Confirm the species’ EPBC Act status and refer the action for environmental assessment if it may have a significant impact on the listed species or its habitat.

Check Western Australian threatened species, fish capture, animal handling, clearing, water abstraction and waterway approval requirements before mobilisation.

Prepare a fauna and aquatic habitat management plan that identifies no-go areas, waterway crossings, sediment controls, dewatering controls, fish rescue arrangements, stop-work triggers and reporting contacts.

Include the species in the project risk register where the works may reduce streamflow, alter groundwater, increase salinity, disturb spawning habitat or allow invasive fish to enter retained habitat.

Before habitat disturbance: Pre-clearance preparation

Complete a targeted aquatic survey and habitat inspection before clearing, excavation, dewatering, bank works or construction in or near suitable habitat.

Mark retained streams, pools, riparian vegetation, groundwater discharge areas and no-go buffers on plans and in the field. The supplied documents do not prescribe a standard buffer width, so set the buffer from a site-specific hydrological and ecological assessment.

Install exclusion fencing or other visible controls where they can keep machinery, vehicles, spoil, fuels and sediment out of retained aquatic habitat.

Stage works so that any necessary aquatic rescue, dewatering or temporary diversion occurs under an approved method and with qualified personnel present.

During habitat disturbance: Daily work controls

The main on-site risks are loss or isolation of shallow aquatic habitat, reduced flow, poor water quality and introduction or spread of invasive fish. Controls must remain active for the whole work period.

Inspect exclusion fencing, no-go markers, sediment controls, drainage controls and waterway crossings before work starts each day.

Keep machinery, refuelling, concrete washout, spoil, chemicals and stockpiled material away from streams, pools, riparian vegetation and groundwater discharge areas.

Prevent turbid water, saline water, contaminated water and altered runoff from entering retained habitat. Do not pump or discharge water to a waterway without approval and treatment under the project plan.

Use clean equipment and inspect pumps, nets, buckets and other aquatic equipment between waterways to reduce the risk of spreading invasive fish, pathogens and poor water quality.

During habitat disturbance: Fauna spotter and machinery interface

The fauna spotter catcher or aquatic ecologist must brief the operator before each work stage and identify the exact exclusion area and approved working limits.

Use a spotter when machinery approaches waterway margins, shallow pools, flooded vegetation, stream banks or other mapped habitat. The spotter must have authority to stop the activity.

Do not allow a general fauna spotter catcher to capture or handle this fish unless their authorisation, training and project plan permit aquatic threatened species work.

If dewatering or isolation of a pool is required, stop the work until an authorised aquatic fauna professional has inspected the area and implemented the approved fish rescue method.

During habitat disturbance: If the fish is found

Stop the activity that could affect the fish, its pool or its connecting stream, and protect the immediate area from machinery, sediment and people.

Do not handle, photograph in a way that delays release, collect or relocate the fish unless the person is authorised under the relevant approvals and the action is covered by the fauna management plan.

Where relocation is authorised, move the fish only to nearby retained habitat with suitable water quality, flow, cover and connectivity, using clean equipment and the approved method. Do not release it into an unrelated catchment or unassessed waterbody.

Send injured fish or other injured fauna to an approved aquatic wildlife rehabilitator or veterinarian where this is authorised and practical, and notify the project environmental officer and relevant authority.

Record the location, date, waterbody, condition, action taken, personnel, photographs where permitted and final outcome.

During habitat disturbance: Stop-work triggers and records

Stop work if a Western Dwarf Galaxias is detected in the work area, if a connected pool or stream is unexpectedly exposed or dewatered, or if flow, groundwater discharge or water quality changes outside the approved controls.

Stop work if sediment, saline water, contaminated water or invasive fish enters retained habitat, or if machinery breaches a marked exclusion area.

Keep daily records of inspections, weather and water conditions, flow changes, water quality incidents, aquatic fauna observations, captures, relocations, injuries, mortalities and corrective actions.

Escalate any unapproved impact to the project environmental officer, the qualified aquatic ecologist and the relevant regulator before restarting.

After habitat disturbance: Completion checks

Completion does not remove the risk to this species. Check that retained habitat still functions, that flow and groundwater inputs are maintained, and that construction controls remain effective through the next wet and dry conditions.

Inspect all retained streams, pools, riparian areas and groundwater discharge sites after clearing, excavation, crossings, dewatering and reinstatement.

Confirm that pools remain connected where they were connected before works, stream beds and banks are stable, and no new barriers, drains, dams or artificial channels are isolating habitat.

Remove temporary crossings, pumps, diversion structures, spoil and exclusion materials only when the environmental officer confirms that removal will not damage habitat or water quality.

Complete a post-work aquatic survey where the project affected suitable habitat, changed flow or groundwater conditions, or triggered a fish rescue.

After habitat disturbance: Monitoring and reporting

Monitor flow, water depth, water quality, bank stability, riparian cover, aquatic vegetation, sediment and invasive fish at locations upstream, downstream and within the work area where required by the management plan.

Continue monitoring through relevant wet and dry conditions where the project may affect groundwater-dependent habitat or seasonal pools.

Compare post-work observations with pre-work survey records and investigate any decline in habitat condition or fish detections.

Provide the completion report to the approval holder and relevant regulators, including maps, survey effort, records of incidents, corrective actions, rehabilitation results and any threatened species records.

After habitat disturbance: Ongoing controls and offsets

Maintain erosion, sediment, weed, access and exclusion controls until the site is stable and the environmental officer signs them off.

Manage any residual significant impact in accordance with the approval, including approved offsets or other compensatory measures where required.

Do not use an offset as a substitute for avoiding or minimising direct impacts to occupied habitat, groundwater inputs or connected pools.

Rehabilitation actions: Restore aquatic and riparian habitat

Rehabilitation should restore the shallow freshwater conditions used by Western Dwarf Galaxias, not just the appearance of the bank. Prioritise flow, groundwater inputs, low salinity, riparian cover, shallow spawning areas and connection between pools and streams.

Reinstate natural stream beds, shallow pool margins and seasonal inundation areas where works have altered them, using a design based on the pre-work channel and local reference sites.

Replant locally appropriate native riparian and wetland vegetation, including vegetation that provides submerged cover and flooded peripheral habitat. Melaleuca-dominated riparian vegetation is associated with adult habitat in streams.

Protect groundwater discharge points and restore surface connections to groundwater-fed tributaries where construction has interrupted them.

Do not deepen or over-clear shallow pools, and do not replace complex natural margins with bare, uniform banks.

Rehabilitation actions: Restore connectivity and water quality

Remove temporary barriers and reinstate fish passage between streams and connected pools where the project has interrupted movement.

Design crossings and drainage so they maintain the natural timing and volume of flows and do not create isolated pools or artificial channels.

Control erosion, sediment, nutrients, salinity and contaminated runoff. The species is generally associated with low-conductivity freshwater below 1 mS/cm and is thought to have low salinity tolerance.

Prevent access by eastern gambusia, redfin perch, trout and other invasive fish, and report any invasion found during rehabilitation monitoring.

Rehabilitation actions: Logs, rocks and artificial habitat

Retain and replace locally occurring woody debris, root structure, leaf litter and stable cover where these features were removed from stream or pool margins.

Do not add hollows, nest boxes or terrestrial fauna structures as a substitute for aquatic habitat. The supplied species information identifies shallow water, riparian vegetation, submerged vegetation and groundwater-fed habitat as the relevant features.

Use only clean materials and equipment in waterways, and ensure imported fill, rock and vegetation cannot introduce invasive fish, weeds, pathogens or altered water chemistry.

Rehabilitation actions: Fire, weeds and success measures

Manage weeds and excessive fuel loads in riparian areas in a way that retains shade, bank stability and flooded vegetation, and avoids sediment or chemical entry to the water.

Plan fire management with the land manager so that fire does not remove riparian cover, expose peat flats or increase erosion and sediment delivery to streams and pools.

Monitor rehabilitation for survival and cover of native riparian vegetation, stable banks, suitable shallow water, maintained flow and groundwater expression, low sediment and salinity, absence or control of invasive fish, and continued use by Western Dwarf Galaxias where monitoring is approved.

Set site-specific completion criteria before works begin and retain monitoring records, photographs, maps and aquatic survey data for the approval period.

Sources

• Consultation on Species Listing Eligibility and Conservation Actions - Galaxiella munda (western mud minnow), Australian Government DCCEEW: https://www.dcceew.gov.au/sites/default/files/documents/consultation-document-galaxiella-munda.pdf
• pone.0038433 1..15, journals.plos.org: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0038433&type=printable