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Dargo Galaxias (Galaxias mungadhan)

The Dargo galaxias is a small, non-migratory freshwater fish endemic to cool alpine and subalpine headwater creeks in eastern Victoria. It is Critically Endangered because its range is very restricted and fragmented, and because trout, fire, drought, sedimentation and altered stream flow continue to reduce habitat quality and population size on development sites.

Conservation status

Commonwealth, EPBC Act 1999: Critically endangered.

Victoria, Flora and Fauna Guarantee Act 1988: Critically endangered.

Breeding season

The annual cycle is poorly documented. The pattern below combines species records with information from the former mountain galaxias complex and should be treated as a planning guide rather than a confirmed species calendar.

Month values are January to December: 0 means not typical, 1 means occurs, and 2 means peak or higher planning concern. The breeding and young-fish timing is uncertain and should be confirmed with current species-specific advice before works.

  • Breeding: Spawning is undocumented but is thought to occur in spring. Fish collected in mid-November and mid-December were at an early stage of development, while fish collected in mid-April were at an advanced stage.
  • Eggs and young: In the former mountain galaxias complex, eggs hatch after about 20 to 30 days. Early developmental stages have been recorded in November and December, and presumed 0+ fish have been recorded from late March, April and early May.
  • Low-flow and fire risk: Drought, declining water levels, fire and post-fire rainfall can affect all life stages. The timing varies between years and is not restricted to one season.
  • Highest clearing risk: Clearing and in-stream disturbance are most likely to harm the species from late winter through spring and into early summer if spawning, eggs or young are present. Because the species is non-migratory and may shelter in the substrate during low flow, disturbance can harm fish in any month.

Identification

The Dargo galaxias is a small, elongated, scaleless fish with a tubular body and soft-rayed, translucent yellow-brown fins. It is usually brown and mottled, but fish from Lightbound Creek can be dark chocolate brown.

Adults are predominantly brown on the back and upper sides, becoming light brown on the lower sides with a tan belly. Diffuse, irregular dark brown to black blotches extend from the back towards the lower sides. A moderately wide mid-lateral band of gold spots or flecks may be visible.

The head and snout are small, the mouth is comparatively large, and the eyes are small and silver to copper-gold. The body has no scales. The fins are soft-rayed, translucent and yellow-brown. Adult fish have climbing flanges on the underside of the pectoral and ventral fin rays.

Usual adult length: 70 to 80 mm length to caudal fin

Maximum recorded length: 110 mm length to caudal fin

Maximum recorded weight: 11 g

Identification: Separating characters

Identification should use a combination of characters rather than colour alone. Compared with other taxa in the former mountain galaxias complex, the Dargo galaxias has a long distance between the pectoral and ventral fin bases, a relatively narrow gap between the eyes, and a lower jaw shorter than the upper jaw.

The climbing flanges on the pectoral and ventral fin rays are useful characters. The species lacks distinct black bars along the lateral line. The Dargo galaxias is the only Galaxias species known from the headwaters of the Dargo River system, although other Galaxias species occur further downstream.

Identification: Field detection

There are no documented terrestrial field signs such as tracks, scats, calls, nests or eyeshine. Detection is by targeted aquatic survey, with fish generally located in shallow riffles and pools and captured or observed using approved freshwater fish survey methods.

Do not rely on visual inspection alone. The species is small, non-migratory and occurs in isolated headwater subpopulations. Electrofishing and handling require appropriate authorisation, qualified personnel and biosecurity controls.

  • Record the creek name, stream reach, water depth, channel width, flow condition, substrate, cover and any trout observed.
  • Photograph fish only where this can be done without prolonging handling or increasing stress.
  • Treat any small Galaxias in suitable headwater habitat as potentially significant until identification is confirmed by an appropriately qualified freshwater fish specialist.

Distribution: National range

The Dargo galaxias is endemic to Victoria and is known from the headwaters of the Dargo River system in eastern Victoria. Its current distribution is highly fragmented, with subpopulations isolated above waterfalls and other barriers.

The species is restricted to Victoria, in the Mitchell and Thomson Rivers region of eastern Gippsland. It occurs in the upper Dargo River system, at approximately 1,150 to 1,620 m above sea level.

The species is non-migratory. It does not undertake diadromous migrations, so a local population cannot be expected to recolonise a disturbed reach from downstream or marine habitat.

Australian states: Victoria only

Bioregional setting: Eastern Gippsland alpine and subalpine headwaters, within the Mitchell and Thomson Rivers region

Distribution: Known subpopulations

Before surveys in 2016, the species was known from two sites in Lightbound Creek, near Dargo High Plains and off Kings Spur Track. Surveys in 2016 recorded 10 additional subpopulations in Precipice, Paw Paw, Tabletop, Eighteen Mile, Frazers, Frosty, Jones, Pike, Shepherd and Twenty-Five Mile creeks.

These subpopulations are isolated from the Lightbound Creek subpopulation above waterfalls. All known subpopulations are important because the species is Critically Endangered and the remaining populations are small and fragmented.

  • Lightbound Creek, including the Dargo High Plains area and the Kings Spur Track area.
  • Precipice, Paw Paw, Tabletop, Eighteen Mile, Frazers, Frosty, Jones, Pike, Shepherd and Twenty-Five Mile creeks.

Distribution: Population size and trend

A reliable current estimate of the total number of mature individuals is not provided in the supplied documents. The population declined by an estimated 50 to 70 percent between 2002 and 2018, with drought and fire implicated in that decline.

Following the 2019 to 2020 bushfires, Victorian assessments reported reduced fish abundance and a high genetic risk rating. Approximately 200 fish were removed for temporary captive management in February 2020 and returned to the capture site in September 2020.

Known subpopulations recorded in 2016: 11, including the previously known Lightbound Creek subpopulation and 10 additional subpopulations

Estimated population decline, 2002 to 2018: 50 to 70 percent

2019 to 2020 fire response: About 200 fish salvaged for temporary captive management

Fire-affected distribution: Approximately 70 percent of the species' distribution was burnt in the 2019 to 2020 bushfires

Current conservation status: Critically Endangered under the EPBC Act and in Victoria

Habitat: Stream form and setting

The Dargo galaxias occupies small, cool, clear alpine and subalpine creeks flowing through grassy plains and forest ecosystems. Suitable habitat is restricted to headwater streams with persistent surface or groundwater flow and a mixture of riffles, pools, rock cover and vegetated margins.

Recorded creeks average about 0.5 to 2 m in width and 0.05 to 0.8 m in depth. They are predominantly made up of riffles and pools, with varying degrees of riparian shading.

The species can survive water temperatures below 5 degrees Celsius in winter, and its catchment is often covered by snow. Suitable habitat is associated with high-elevation alpine and subalpine conditions.

Recorded elevation: 1,150 to 1,620 m above sea level

Average creek width: 0.5 to 2 m

Average creek depth: 0.05 to 0.8 m

Winter water temperature: The species can survive below 5 degrees Celsius

Habitat: Habitat structure

The streambed is mostly bedrock, with loose boulders and smaller amounts of cobble, pebble, gravel, sand and clay. Backwaters may contain silt.

Rock, undercut banks and vegetation overhang provide instream cover. Riparian grasses and other vegetation also help maintain shade, bank stability and low sediment inputs.

  • Protect the full drainage network, including wet and dry channels and headwater drainage lines.
  • Avoid clearing, soil disturbance, machinery access and stock or feral animal access near stream banks.
  • Maintain stream flow, clean coarse substrate, pools, riffles, overhanging vegetation and natural barriers that exclude trout.

Habitat: Habitat critical to survival

Habitat critical to survival includes known subpopulation sites and similar adjoining habitat that could support range extension through natural movement or translocation. The most suitable adjoining areas are those without introduced salmonids and with enough surface water or groundwater to maintain the creek.

No Critical Habitat has been identified or entered in the Register of Critical Habitat under the EPBC Act. This does not remove the need to protect known occupied streams and adjoining suitable headwater habitat.

Foraging habitat: Food

The species' diet has not been studied directly. Information from the former mountain galaxias complex indicates that it feeds on small aquatic and terrestrial invertebrates in and around flowing headwater creeks.

The likely diet includes benthic, drifting aquatic and terrestrial macroinvertebrates. Reported prey for the mountain galaxias complex include insects, crustaceans, molluscs, worms and spiders.

No species-specific food plant, prey density or foraging range has been established.

Likely prey: Aquatic and terrestrial macroinvertebrates, including insects, crustaceans, molluscs, worms and spiders

Foraging range: Not documented; the species is non-migratory and is associated with its occupied headwater creek reach

Foraging habitat: Foraging habitat on project sites

Retain riffles, pools, coarse bed material, backwaters, undercut banks and vegetation overhang. These features provide access to benthic and drifting prey and also provide cover.

Prevent sediment pulses, turbidity, chemical contamination, reduced flow and loss of riparian vegetation. Fire, earthworks, unsealed roads, track crossings and stock or feral animal access can reduce food availability by smothering the streambed or altering water quality.

  • Keep fuels, concrete washout, herbicides, sediment and other pollutants out of the drainage network.
  • Use sediment and erosion controls before ground disturbance begins, including at stream crossings and on unsealed roads.
  • Do not infer that a dry channel is unused habitat, because the species may seek refuge in the substrate during declining water levels.

Breeding habitat: Breeding biology

Breeding biology is poorly known and most available information comes from studies of the former mountain galaxias complex. Breeding habitat is likely to be shallow, flowing creek habitat with clean rocky substrate and adequate year-round flow.

The spawning period has not been documented for the Dargo galaxias. It is thought to occur in spring, but the timing may vary with local conditions. Sampling records indicate early development in fish collected in mid-November and mid-December, and advanced development in fish collected in mid-April.

In the mountain galaxias complex, eggs are small, about 2 mm in diameter, spherical, demersal and adhesive. They are laid in sticky masses attached to rocky substrates. Eggs hatch after about 20 to 30 days, with larvae about 9 mm long after hatching.

Spawning season: Unknown for the species, but thought to be in spring, with possible annual variation

Annual egg production: Fewer than 400 eggs annually in species of the former mountain galaxias complex

Egg size: About 2 mm diameter

Egg development: About 20 to 30 days to hatching

Larval size at hatching: About 9 mm

Age at maturity: Not documented

Lifespan: Not documented

Breeding habitat: Breeding habitat features

Potential spawning habitat includes clean rocky sections of shallow creeks, particularly riffles and pool margins. Rocky substrate is important because adhesive eggs in the former mountain galaxias complex attach to rock.

Maintain natural low flows, water quality, coarse substrate, bank cover and riparian vegetation during the likely breeding period. Sediment deposition can smother spawning substrate and reduce food, refuge and recruitment habitat.

  • Avoid in-stream works, dewatering, bed disturbance and sediment release in occupied or adjoining suitable creeks.
  • Keep fire retardant, herbicide, fuels and other chemicals out of the stream.
  • Maintain barriers that exclude introduced salmonids, unless a barrier modification is part of an approved species recovery action.

Sheltering habitat: In-stream refuges

Shelter is provided by the physical complexity of small headwater creeks. The species has no known terrestrial refuge, den or nest, but may use the streambed when surface water levels fall.

Known cover includes bedrock, boulders, undercut banks and vegetation overhang. Pools and backwaters provide deeper water than adjacent shallow riffles.

During declining water levels and surface water loss, Dargo galaxias and related Galaxias species are suspected to burrow into the substrate. This behaviour has not been confirmed as a species-specific observation.

Known shelter features: Rock, bank and vegetation overhang, pools and coarse streambed material

Possible drought refuge: Burrowing into the substrate during declining water levels

Refuge dimensions: Not documented

  • Retain pools, riffles, coarse bed material, undercut banks and overhanging riparian vegetation.
  • Do not place sediment, spoil, slash or debris in the channel or on the active bank.
  • Avoid compaction and disturbance of the streambed, including during access, crossings, pumping and dewatering.

Sheltering habitat: Barriers and refuge security

Climbing flanges on the pectoral and ventral fins suggest that the species can negotiate some instream barriers, including waterfalls. Despite this, waterfalls and other barriers isolate the known subpopulations and also help prevent trout invasion.

Do not remove, fill, drown out or otherwise alter natural barriers unless the action has been assessed and approved as part of species recovery planning.

  • Inspect stream crossings and temporary works for changes that could allow trout or other non-native fish to move upstream.
  • Keep fish passage works, pumping and water diversions under an approved aquatic fauna management plan.
  • Use disease and aquatic pest biosecurity between catchments and between occupied creeks.

Threats: Introduced trout

The Dargo galaxias has a very small, fragmented distribution and low numbers of mature fish. Any project that changes flow, water quality, bed material, riparian cover or barriers in an occupied or adjoining headwater creek can affect the species.

Brown trout and rainbow trout are the highest priority biological threat. They prey on Dargo galaxias, compete for food and shelter, and have historically fragmented the species' range.

Further trout incursion could rapidly remove a subpopulation. Incursion may occur when high flows drown out barriers or through illegal or accidental fish stocking.

  • Do not stock or transfer non-native fish, water, equipment or aquatic animals into occupied catchments.
  • Maintain natural or artificial barriers that exclude trout, with routine inspection and maintenance.
  • Report trout, fish deaths, damaged barriers or suspected illegal stocking promptly to the relevant Victorian authority.

Threats: Fire, drought and hydrology

Fire can remove riparian cover, increase water temperature, reduce dissolved oxygen and deliver ash and sediment to creeks after rain. Sediment can smother food, refuge and spawning habitat and can prevent fish from burrowing into the substrate during low flows.

Drought and climate change can reduce stream flow, create new barriers, reduce wetted habitat and reduce spawning and recruitment. Intense rainfall can also increase debris flows and allow trout to cross barriers.

Fire impact in 2019 to 2020: Approximately 70 percent of the species' distribution was burnt

Observed post-fire response: Victorian assessments reported reduced fish abundance and a high genetic risk rating

  • Include mapped Dargo galaxias records and likely habitat in fire plans, access plans and incident response maps.
  • Keep machinery, fire suppression chemicals and disturbed soil away from occupied drainage lines.
  • Maintain surface and groundwater inputs needed to keep occupied headwater habitat wet.

Threats: Clearing, roads and sediment

Clearing riparian vegetation, constructing roads or firebreaks, and operating machinery near stream crossings can increase erosion and sediment delivery. Recreation and unsealed tracks near Lightbound Creek can widen tracks, damage vegetation and pollute waterways.

Feral pigs, horses, deer and domestic stock can trample banks, graze riparian vegetation and wallow in streams. These impacts increase erosion, turbidity and siltation and can reduce feeding, refuge and spawning habitat.

  • Avoid clearing or soil disturbance within riparian protection zones and across wet or dry drainage lines.
  • Design crossings to prevent direct sediment entry, channel damage and altered low flows.
  • Fence or otherwise exclude domestic stock and feral ungulates from occupied stream banks where required.
  • Stabilise disturbed ground before rain and inspect erosion controls after high rainfall.

Threats: Disease and water quality

Parasitic flatworm cysts have been reported in species of the former mountain galaxias complex. The prevalence and population-level effect in Dargo galaxias are unknown.

Poor water quality from sediment, ash, fire retardant, herbicide, fuel, concrete or other contaminants can injure or kill fish and reduce food and spawning habitat.

  • Use clean, disinfected equipment between catchments and follow approved aquatic fauna biosecurity procedures.
  • Do not release captured fish, water, bait or equipment into another creek.
  • Keep chemicals, sediment and contaminated runoff out of occupied and potentially occupied headwaters.

Threats: Survey and project controls

The species is non-migratory and occurs in small isolated populations, so local mortality may not be offset by recolonisation. Survey planning should account for occupied sites, adjoining suitable habitat and barriers that separate subpopulations.

Fish handling, electrofishing, salvage and translocation require relevant approvals and qualified aquatic fauna personnel. Emergency salvage after fire is time-sensitive because post-fire rainfall can rapidly deliver ash and sediment to streams.

  • Obtain current species records and approvals before clearing, construction, water extraction, crossing works or fire response in the Dargo headwaters.
  • Use a suitably qualified freshwater fish ecologist to assess potential habitat and prepare any capture, exclusion, dewatering or salvage method.
  • Stop work and seek specialist advice if a Galaxias is found in a project-affected creek or if stream flow, bed material or water quality changes unexpectedly.

Survey methodology: 1. Electrofishing survey

The Dargo galaxias is a small, non-migratory freshwater fish confined to cool, clear alpine and subalpine headwater creeks. Surveys must cover shallow riffles, pools, backwaters and instream cover in the Dargo River headwaters, and must account for isolated subpopulations and low abundance.

Use a portable backpack electrofishing unit operated by trained personnel, with a second person using a dip net. The documented method works upstream during daylight and targets all available habitats with the anode.

Survey riffles, pools, backwaters, rock cover, bank overhang and vegetation overhang. Record creek width, water depth, flow, substrate, cover, water quality and evidence of introduced salmonids.

Place captured fish in a bucket, identify them, and record fork length or total length in millimetres and weight in grams where appropriate. Return fish to the capture site after recovery.

The species has been recorded in creeks averaging 0.5 to 2 m wide and 0.05 to 0.8 m deep, with mainly bedrock, boulders and cobbles. Give particular attention to these habitats.

Typical adult size: 70 to 80 mm length to caudal fin; maximum recorded size 110 mm and 11 g

Recorded density: 4.2 to 6.4 fish per square metre in one Victorian assessment

Survey timing in the documented method: Daytime, moving upstream

Survey methodology: 2. Site coverage and detection

Survey the full area that could be affected, including upstream and downstream reaches, tributary headwaters, dry channels that may reconnect during flows, and adjoining similar habitat that could support the species.

Include known or modelled habitat near the works. Current records include 11 isolated subpopulations in Lightbound, Precipice, Paw Paw, Tabletop, Eighteen Mile, Frazers, Frosty, Jones, Pike, Shepherd and Twenty-Five Mile creeks.

Treat a negative result cautiously. The species is restricted, often isolated above barriers, and may occur at low abundance. Record the length of creek surveyed, habitat sampled, electrofishing time, number of passes, crew, equipment and conditions so that detection effort is clear.

Survey for introduced brown trout and rainbow trout at the same time. Confirm species identifications and photograph unusual or potentially ambiguous galaxias specimens before release, where this can be done safely and lawfully.

Known elevation range: 1150 to 1620 m above sea level

Known creek habitat: Cool, clear alpine and subalpine creeks with riffles and pools

Known barriers: Subpopulations are isolated from the Lightbound Creek subpopulation above waterfalls

Survey methodology: 3. Post-fire, rainfall and sediment risk checks

Where fire, clearing, roadwork or earthworks may increase sediment delivery, inspect the creek before and after forecast rainfall and after major runoff events.

Assess ash, sediment, debris, bank erosion, water temperature, turbidity, dissolved oxygen where available, and loss of riffle, pool or spawning substrate. Fire and post-fire runoff can smother substrate, reduce food and refuge, and reduce water quality.

If a high-risk sediment event is possible, arrange reconnaissance and any required salvage with the relevant aquatic fauna specialists before the event. Victorian experience indicates that reconnaissance and extraction should begin as soon as practicable after fire, preferably within one week and before post-fire rainfall where possible.

Do not apply fire retardant, foam, herbicide or other chemicals where they can enter occupied or potentially occupied streams without approval and species-specific risk controls.

Survey methodology: Minimum effort and reporting

Use a qualified aquatic ecologist and trained electrofishing crew, and document the method rather than reporting only whether fish were detected.

Submit confirmed records, including negative survey results where relevant, to the relevant Victorian wildlife or biodiversity database and provide records to the project approval authority.

Report coordinates, datum, date, start and finish time, waterway, reach length, habitat sampled, electrofishing effort, weather and flow conditions, all fish captured, lengths, weights, photographs, trout observations and the fate of each animal.

Retain field sheets, calibration and equipment records, chain of custody for any specimens, permits, photographs and the names and authorisations of all people handling fauna.

Before habitat disturbance: Avoid and minimise

Plan works around the species' very small, fragmented headwater habitat. Avoid changing stream flow, water quality, barriers or riparian protection zones, and obtain advice before disturbing any creek, drainage line or wet area connected to known habitat.

Keep works out of known subpopulation reaches and adjoining cool, clear headwater creek habitat wherever practicable.

Retain riffles, pools, shallow runs, bedrock, boulders, cobbles, bank overhang, vegetation overhang and riparian protection zones.

Maintain natural or approved barriers that exclude introduced salmonids. Do not create a passage for brown trout, rainbow trout or other non-native fish through crossings, temporary diversions or high-flow pathways.

Prevent changes to surface water and groundwater that could reduce flow, dry pools, increase temperature or interrupt connectivity between occupied habitat and refuge areas.

Avoid new sediment sources from roads, tracks, crossings, machinery, stock access, spoil, drainage, trenching and bank disturbance.

Before habitat disturbance: Approvals and work planning

Check whether the proposed action is likely to have a significant impact on this EPBC Act Critically Endangered species and refer it under the EPBC Act where required.

Confirm Victorian Flora and Fauna Guarantee Act requirements, permits, wildlife handling authorisations, electrofishing permissions and any park, reserve, waterway or land manager approvals before works begin.

Prepare a fauna management plan that identifies known records, likely habitat, survey results, exclusion zones, sediment and water quality controls, fauna handling arrangements, stop-work triggers and reporting responsibilities.

Schedule in-stream or bank works outside periods of low flow, drought, fire recovery and high runoff where practicable. The spawning period is unknown and may vary with conditions, although spring spawning is suspected, so obtain species-specific advice before setting a breeding exclusion period.

Stage works so that occupied habitat, clean water and fish passage remain available throughout construction.

National status: Critically Endangered under the EPBC Act

Victorian status: Critically Endangered

Generation length: About 2 to 4 years, with a best estimate of 3 years in the Australian Government advice; Victorian assessment estimates 3 to 4 years

Before habitat disturbance: Site preparation

Complete a pre-clearance aquatic survey before machinery enters the creek, drainage line or adjoining riparian area, and repeat it if the design, footprint, flow or timing changes.

Mark the approved work footprint, no-go habitat, access routes, refuelling areas, spoil areas and machinery exclusion zones on plans and on the ground.

Install exclusion fencing where it can keep people, vehicles, stock and spoil out of retained stream habitat without blocking fish passage or concentrating runoff into the creek.

Brief all workers to recognise a small, elongated, scaleless brown fish with dark blotches and a gold-flecked mid-lateral band, and to report any galaxias or trout immediately.

Locate and protect waterway crossings, banks, undercut areas, rocks, logs and vegetation that provide cover. Do not remove habitat features unless the fauna management plan specifically allows it.

During habitat disturbance: Daily controls and machinery coordination

Keep machinery, sediment and contaminated water away from occupied or potentially occupied creeks. The fauna spotter catcher must work as part of the construction crew's daily control system, with authority to pause work when aquatic habitat or fish are at risk.

Inspect exclusion fencing, silt controls, diversion structures, crossings, pumps, hoses and creek banks before work starts each day and after rainfall.

Use clean machinery and keep refuelling, chemical storage, concrete washout, spoil and dirty water away from the drainage network.

Keep machinery on approved access routes. Do not drive through water unless the approved method specifically requires it and protects fish, substrate and water quality.

Maintain downstream water quality and fish passage during dewatering, temporary diversions and crossings. Use screened pumps and prevent fish being drawn into hoses or pumps.

The spotter catcher must remain in direct communication with the operator and supervisor, watch the active work area and downstream pathway, and stop or pause the activity before an animal or habitat feature is disturbed.

During habitat disturbance: Fish handling and finds

If a galaxias is found, stop the activity that could affect it and keep the fish in water using clean, suitable equipment.

Only an appropriately authorised person may capture, identify, measure, hold or relocate the fish. Do not handle it unnecessarily or move it between catchments.

Where relocation is approved, move the fish only to nearby retained habitat that is suitable, connected where appropriate, free of introduced salmonids and approved by the relevant authority or species specialist.

Do not relocate fish across a waterfall, catchment boundary or project footprint without a written translocation or salvage plan. The conservation advice states that translocations require relevant state legislation, policies, protocols and guidelines.

Record the exact location, time, habitat, condition, identification, measurements, person handling the fish, destination and release time. Photograph the fish only if this does not extend handling.

During habitat disturbance: Stop-work triggers and incident response

Stop work immediately if a Dargo galaxias is found in the impact area, if fish are stranded or drawn into a pump, or if water becomes turbid, contaminated, unusually warm or disconnected from retained habitat.

Stop work if sediment, ash, fuel, concrete, herbicide, fire retardant or other chemicals enter the creek or if a barrier is damaged and could allow trout or other non-native fish to enter.

Notify the fauna spotter catcher supervisor, aquatic ecologist, construction environmental manager and approval authority as required by the fauna management plan.

Send injured fish to a suitably equipped aquatic facility or other approved wildlife care arrangement. Do not release injured, diseased or unidentified fish without specialist direction.

Keep a daily fauna log, including inspections, captures, deaths, injuries, relocations, water quality incidents, rainfall, corrective actions, stop-work events and approvals to recommence.

After habitat disturbance: Post-work checks

Clearance is not complete when machinery leaves. Check the retained creek and downstream reach for delayed sediment, stranding, barriers and fish mortality, then keep controls in place until the site is stable.

Inspect the work area, upstream and downstream reaches, banks, crossings and temporary water controls after each work stage and after substantial rainfall.

Check for stranded fish, dead or injured fish, sediment deposition, ash, debris, bank collapse, altered flow, blocked passage, exposed pipes and loss of instream cover.

Remove temporary barriers, pumps, hoses, spoil and waste without releasing dirty water or trapping fish. Reinstate the approved channel and fish passage before demobilisation.

Repeat aquatic surveys where the approval, fauna management plan or aquatic ecologist identifies a risk of delayed mortality or recolonisation failure.

After habitat disturbance: Monitoring and reporting

Monitor water quality, flow, turbidity, sediment movement, bank stability, riparian recovery and introduced salmonids at the frequency set in the approval or fauna management plan.

Use the same reach boundaries and survey method on repeat visits so changes in abundance and habitat condition can be compared. The documented Victorian method records captured animals, measurements and return to the capture site.

Report all Dargo galaxias observations, mortality, injuries, relocations, trout detections, incidents and corrective actions to the relevant approval authority and state biodiversity database.

Maintain sediment, erosion, exclusion and chemical controls until monitoring shows that the risk to the creek has ended.

After habitat disturbance: Offsets and residual impacts

Demonstrate that impacts were avoided and minimised before relying on any offset or compensatory measure.

Seek approval advice where works have caused unavoidable loss or degradation of Dargo galaxias habitat. Any offset or conservation action should support salmonid exclusion, secure flow and water quality, protect all populations and improve the species' long-term persistence.

Do not treat translocation as an offset or as a substitute for retaining occupied habitat. Translocations require a separate, approved plan and ongoing management.

Rehabilitation actions: Restore creek and riparian habitat

Rehabilitation should restore cold, clear, flowing headwater creek habitat and prevent trout access. It must address the creek, banks, drainage lines and sources of sediment, not only the construction footprint.

Re-establish stable banks and vegetated protection zones along the entire affected drainage network, including wet and dry channels and headwater drainage lines.

Use locally appropriate native alpine and subalpine riparian vegetation suited to the site. Do not plant species or install structures that shade, block or simplify the shallow riffle and pool habitat used by the fish.

Reinstate natural bedrock, boulder, cobble and pebble structure where it was removed, and retain bank and vegetation overhang that provides cover.

Remove weed sources and prevent grazing, trampling, wallowing and machinery access that could increase erosion or siltation.

Reference habitat dimensions: Creeks average 0.5 to 2 m wide and 0.05 to 0.8 m deep

Typical habitat form: Cool, clear creeks with riffles and pools

Typical substrate: Mainly bedrock, with boulders, cobbles and smaller amounts of pebble, gravel, sand and clay

Rehabilitation actions: Protect flow, barriers and water quality

Design drainage, crossings and erosion controls to maintain adequate surface and groundwater flow and prevent sediment entering the creek.

Retain approved natural or artificial barriers that prevent salmonid invasion, inspect them after high flows and repair damage promptly.

Do not stock, release or allow accidental entry of brown trout, rainbow trout or other non-native fish into rehabilitated or proposed translocation habitat.

Coordinate fire planning with the land manager and fire authorities. Protect known occurrences and likely habitat from avoidable fire suppression chemicals, severe sedimentation and loss of riparian cover.

Rehabilitation actions: Monitoring and success measures

Monitor rehabilitation until banks are stable, vegetation is established, water quality and flow are suitable, and no project-related sediment source remains.

Use repeat electrofishing surveys by qualified personnel to assess fish presence, abundance, size structure and recruitment, while recording effort and habitat conditions consistently.

Treat successful rehabilitation as retention or recovery of cool, clear flowing water, stable riffles and pools, suitable cover, maintained fish exclusion barriers, no project-related fish mortality and no new trout incursion.

Investigate declining counts, loss of young fish, drying pools, rising sediment, damaged barriers or new trout detections promptly with the relevant aquatic ecologist and land manager.

Sources