Lorentz Grunter (Pingalla lorentzi)

Conservation status

Northern Territory, Territory Parks and Wildlife Conservation Act 1976: Vulnerable.

Breeding season

The seasonal pattern is based on the reported November to February spawning period and the observation of juveniles in September. Movement and dispersal timing is not described in the supplied sources.

Months are January to December. The seasonal pattern is indicative because the sources provide limited observations and no detailed population phenology.

• Breeding: Spawning appears to occur in the early to middle wet season, approximately November to February.
• Breeding: The reported spawning period extends through January and February. Males guard and fan the eggs.
• Young: Juveniles have been observed in September, indicating recruitment from the preceding wet-season spawning period.
• Highest clearing risk: Disturbance is most likely to harm the species during the November to February breeding period, when eggs may be guarded in affected freshwater habitat. Habitat damage can affect fish year round.

Identification

Lorentz Grunter is a small, perch-like freshwater fish with a generally silver body. It is most reliably identified from a combination of body markings and fin characters.

Adults reach about 20 cm in length. The body is uniformly silver, with darker scale margins on the upper surface.

A white stripe extends from below the eye to the upper lip. The fins are mostly transparent to dusky, and the anal fin has a dark grey to blackish blotch.

The dorsal fin has 13 to 14 spines and 11 to 13 soft rays. The anal fin has three spines and eight to nine soft rays.

Identification: Size and sex

The maximum recorded length is 20.0 cm standard length. No weight range, sexual differences, age at maturity or other reliable field characters separating males and females are provided in the supplied sources.

Male parental care is recorded during breeding, with males guarding and fanning the eggs.

Maximum length: 20 cm

Weight: Not reported in the supplied sources

Sexual identification: No external sex characters are described

Identification: Similar species and field signs

The supplied sources do not provide a comparison with similar grunters or other freshwater fish. Identification should therefore use the silver body, white eye to upper-lip stripe, dark anal-fin blotch and dorsal-fin counts together, with confirmation by an experienced freshwater fish specialist where required.

Lorentz Grunter does not produce terrestrial field signs such as tracks, scats, nests, calls or eyeshine. Its presence is established by live or preserved fish records, reliable photographs, or environmental DNA and targeted freshwater fish survey methods where those methods are appropriate.

• Record the waterbody, pool location, substrate, water temperature, habitat shading and survey method for each observation.
• Photograph the whole fish and the head, anal fin and dorsal fin where handling permits.
• Use appropriate animal ethics, permits and decontamination procedures when capturing or moving freshwater fish between sites.

Distribution: Australian range

Lorentz Grunter has a patchy distribution in northern Australia and southern New Guinea. Australian records are limited, and the Northern Territory government identifies the Finniss River as the only known Northern Territory location.

The species is reported from the Northern Territory and far north Queensland. Within the Northern Territory, it is known only from the Finniss River.

The supplied sources do not identify the relevant Australian bioregions. They also do not provide a complete locality list, mapped subpopulations or confirmed sites outside the Finniss River in the Northern Territory.

Northern Territory: Known only from the Finniss River

Queensland: Reported from far north Queensland

Bioregions: Not specified in the supplied sources

Distribution: Strongholds and population status

The Finniss River is the only named Australian stronghold in the supplied sources. No population estimate, abundance estimate, generation length, trend or number of subpopulations is provided.

The Northern Territory government identifies the distribution as very limited and recommends further surveys in the Finniss River and adjacent catchments, together with monitoring at known sites.

Known Northern Territory localities: Finniss River

NT conservation reserves with records: None reported

Population size and trend: Unknown

• Treat suitable pools and connected freshwater reaches in the Finniss River catchment as potential habitat until targeted surveys demonstrate otherwise.
• Report new records with precise coordinates, photographs or voucher information, habitat details and survey effort.

Distribution: Wider range

Outside Australia, Lorentz Grunter is reported from southern New Guinea. FishBase gives the broader distribution as New Guinea and Australia and describes a tropical range between approximately 3 degrees south and 15 degrees south.

Habitat: Waterbodies and substrates

Lorentz Grunter uses tropical freshwater streams and waterbodies, including both flowing and still water. Adults are associated particularly with large pools in open, unshaded stream sections.

Adults occur in lentic and lotic freshwater. Reported settings include backwaters, swamps, turbid channels of large rivers and small to large pools.

Pools with rock and sand substrates are typical. The fish uses open, unshaded sections of streams rather than being restricted to heavily vegetated or shaded margins.

• Retain large pools, backwaters and connected stream reaches during site planning and construction.
• Avoid sediment, spoil, concrete wash water, hydrocarbons and other pollutants entering pools or connecting channels.
• Protect both rocky and sandy pool substrates from unnecessary excavation, smothering and bed disturbance.

Habitat: Climate and water conditions

The species is tropical and is generally associated with water temperatures between 25°C and 30°C.

The supplied sources do not give an elevation limit, flow threshold, depth range, dissolved oxygen requirement or specific vegetation community.

Typical water temperature: 25°C to 30°C

Climate zone: Tropical

Elevation limit: Not reported

Habitat: Development-site habitat

Development, mining, agriculture and poor land management can affect the species through loss or degradation of riparian vegetation, erosion, pollution, altered water flow and reduced water quality.

The Northern Territory species profile does not identify a required riparian width. Retain riparian vegetation and maintain natural connections between pools wherever practicable.

• Plan crossings and in-stream works to minimise changes to pool structure, flow paths and sediment transport.
• Keep cleared areas, stockpiles and access tracks away from drainage lines and known or potential pools where practicable.
• Use sediment and erosion controls before ground disturbance starts and maintain them until exposed soil is stabilised.

Foraging habitat: Diet

Lorentz Grunter feeds mainly on benthic algae and other plant material attached to or occurring on hard and sandy surfaces. Its feeding adaptations indicate close grazing or scraping of the substrate rather than pursuit of large mobile prey.

The diet consists primarily of benthic algae. The teeth are adapted to scrape algae and other plant material from rock and wood surfaces and from sandy substrates.

FishBase also describes the species as omnivorous, but the Northern Territory profile identifies benthic algae as the primary food.

Primary food: Benthic algae

Other food: Plant material

Feeding mode: Scraping surfaces and sandy substrates

Foraging habitat: Foraging areas

Foraging habitat includes the rock, wood and sand surfaces of pools and other freshwater reaches. The sources do not provide a foraging range, daily movement distance, home range or specific algal species.

Works that increase turbidity, bury substrates, remove woody material or alter flow can reduce the surfaces and water conditions used for feeding.

• Maintain a variety of clean rock and sand surfaces within suitable pools.
• Prevent fine sediment and construction pollutants from coating feeding surfaces.
• Avoid unnecessary removal of submerged wood in occupied or potentially occupied pools.

Breeding habitat: Breeding biology

Spawning appears to occur in the early to middle wet season. Males guard and fan the eggs, but the sources do not describe the spawning surface, nest dimensions, egg number or development time.

Juveniles observed in September indicate spawning in the preceding early to middle wet season, approximately November to February. Eggs are guarded and fanned by the male parent.

The supplied sources do not provide clutch size, incubation period, age at maturity, lifespan or a confirmed spawning substrate.

Breeding season: Approximately November to February

Egg care: The male guards and fans the eggs

Clutch or egg number: Not reported

Incubation period: Not reported

Age at maturity: Not reported

Lifespan: Not reported

Breeding habitat: Breeding habitat

Breeding habitat is likely within the species' freshwater pool and stream habitat, but the specific spawning microhabitat has not been described in the supplied sources.

During the breeding period, avoid dewatering, blasting, heavy vibration, bed excavation, sediment release and rapid changes in flow or water quality at known sites.

• Schedule in-stream works outside November to February where practicable, subject to site-specific survey findings and approvals.
• Maintain suitable pool connectivity and water levels through the wet season.
• Treat adult fish, eggs and juveniles as potentially present even when adults are not detected.

Sheltering habitat: Known refuge settings

No specific refuge, nest, burrow, hollow or cover structure is described for Lorentz Grunter. The species is associated with freshwater pools and stream reaches, including open and unshaded sections.

Adults occur in large pools, backwaters, swamps and turbid river channels. The sources do not state whether the species requires undercut banks, submerged wood, dense aquatic vegetation, crevices or particular water depths for shelter.

The male guards and fans the eggs, so local spawning sites may be particularly sensitive to disturbance even though their physical structure is not documented.

Known shelter type: No specific shelter structure reported

Pool substrate: Rock and sand

Refuge dimensions: Not reported

• Retain pool habitat, rock and sand substrates, submerged wood and connected refuge areas unless surveys and design assessment show they are not required.
• Do not assume that open, unshaded water lacks fish habitat.
• Avoid isolating pools from adjacent freshwater reaches during temporary works or altered drainage.

Sheltering habitat: Survey and works implications

Fish may be present in pools, backwaters and turbid channels even when visual detection is poor. Targeted freshwater fish surveys should be designed by suitably qualified personnel and should account for waterbody type, access, season and animal welfare requirements.

Where fish relocation is proposed, obtain the required permits and use approved methods. Do not move water, sediment, aquatic plants, equipment or captured animals between catchments without appropriate biosecurity controls.

Threats: Clearing and construction

Lorentz Grunter has a limited known Australian distribution and occurs close to Darwin. The main project risks are damage to freshwater habitat, riparian vegetation, flow, water quality and substrates.

Development can degrade waterways and riparian vegetation. Clearing, earthworks, access tracks, crossings and in-stream construction can increase erosion, sediment loads, pollution and physical disturbance of pools.

Mining, agricultural development and poor land management are also identified as sources of altered water flow and water quality.

• Avoid clearing riparian vegetation beside known or potential habitat.
• Stage earthworks so exposed soil does not drain into pools or stream channels.
• Install and maintain erosion, sediment and spill controls before work begins.
• Keep concrete, fuels, chemicals, wastewater and contaminated water out of freshwater habitat.

Threats: Flow, water quality and fire

Altered water flow, erosion and pollution can affect the species' freshwater habitat and feeding surfaces. Changes to water quality may also affect the temperature and physical condition of pools.

Altered fire regimes are identified as a potential threat, although the supplied sources do not describe a specific fire response or fire interval for Lorentz Grunter.

• Maintain natural flow paths and avoid rapid changes in pool levels caused by diversion, pumping or drainage works.
• Prevent sedimentation and pollution from entering occupied or connected freshwater habitat.
• Assess proposed fire-regime changes near riparian corridors and catchments as part of the project impact assessment.

Threats: Invasive aquatic plants

Parrots feather, Myriophyllum aquaticum, can form dense mats that shade native aquatic plants, impede water flow and alter water temperature and dissolved oxygen. The Northern Territory weed assessment identifies Lorentz Grunter in the Finniss River as potentially threatened by this plant.

Although parrots feather had not naturalised in the Northern Territory at the time of the weed assessment, it had been detected in a Darwin suburban pond and can spread through stem fragments, water, boats, wildlife and equipment.

• Prevent aquatic weed fragments from being moved between waterbodies on boats, machinery, clothing or survey equipment.
• Inspect, clean, drain and dry equipment before leaving a freshwater site.
• Report suspected parrots feather infestations through the relevant Northern Territory weed management pathway.

Threats: Other threats and knowledge gaps

The supplied sources do not identify roads, vehicle strike, introduced predators, disease or fishing as confirmed threats for Lorentz Grunter. These issues should not be assumed to be absent, but species-specific evidence was not provided.

The Northern Territory government recommends defining the distribution and status more clearly, assessing threatening processes and establishing monitoring at known sites.

Key information gap: Distribution and population status are incompletely defined

Recommended management: Survey adjacent Finniss River catchments and monitor known sites

• Record all fish observations and non-detections with survey effort and habitat details.
• Use pre-clearance and construction monitoring at known sites where works could affect pools, riparian vegetation, flow or water quality.
• Refer unexpected records or fish kills to the relevant Northern Territory wildlife and aquatic biosecurity authorities.

Survey methodology: 1. Define and inspect aquatic habitat

Lorentz Grunter is known in the Northern Territory only from the Finniss River, but its wider distribution and population status are poorly defined. Survey effort should focus on large freshwater pools and connected stream sections with rock or sand substrates, especially open, unshaded habitat. [Sources are listed in each block.]

Map all permanent and seasonal freshwater habitat that could be connected to the works, including large pools, backwaters, channels and adjacent stream reaches.

Prioritise open, unshaded sections with rock or sand substrates and water temperatures between 25°C and 30°C, because these are the recorded adult habitats.

Inspect upstream and downstream connections so that potential movement between retained and disturbed habitat is considered.

Known NT distribution: Finniss River only

Recorded adult habitat: Lentic and lotic freshwater, including large pools, backwaters, swamps and turbid channels

Typical water temperature: 25°C to 30°C

Substrates: Rock and sand

• Record pool dimensions, substrate, water depth, flow, shade, aquatic vegetation, water quality and barriers to movement.
• Map any aquatic weed infestation, particularly parrots feather, because dense mats can reduce habitat quality, alter dissolved oxygen and impede water flow.

Survey methodology: 2. Fish survey methods

The supplied documents do not specify a Lorentz Grunter survey guideline, standard trap effort or detection probability. Use methods approved by the relevant state or territory wildlife and fisheries authority and select methods suited to the waterbody and its access conditions.

Use a combination of non-destructive methods where practicable, such as baited or unbaited traps, seine or dip nets, visual searches and underwater observation, with electrofishing only by appropriately trained and authorised personnel.

Survey both the affected reach and connected retained habitat because the species is patchily distributed and its occurrence may be more widespread in the Finniss River and adjacent catchments.

Species-specific survey effort in supplied documents: Not specified

Recommended approach: Use multiple approved methods and survey connected habitat

• Record the method, gear, number of traps or net sets, soak or search time, survey area, water conditions, operator qualifications and all species captured or observed.
• Release captured fish promptly at the point of capture unless an authorised permit or animal welfare direction requires another action.
• Do not present trap nights, transect lengths or search hours as species-specific minimums unless they are set by the approving authority or project permit.

Survey methodology: 3. Timing and detection

Plan surveys across suitable warm-water conditions where possible, while complying with seasonal restrictions, permits and weather safety requirements.

Include consideration of the early to middle wet season, from November to February, when spawning is thought to occur, and September, when juveniles have been observed.

Use repeated visits when the first survey does not detect fish, because the species is patchily distributed and adults may occur in lentic or lotic habitat.

Likely spawning period: November to February

Juvenile observation period: September

Maximum recorded length: About 20 cm

• Avoid concluding that the species is absent from a reach after a single unsuccessful visit.
• Record rainfall, recent flow changes, turbidity, water temperature, visibility, aquatic vegetation and disturbance at every visit.
• Use fish size, the white stripe below the eye to the upper lip, silver body, dark scale margins and dark anal-fin blotch to support identification, and retain clear photographs where handling is permitted.

Survey methodology: Minimum effort and reporting

• Obtain written advice from the relevant Northern Territory or other state or territory authority on approved fish survey methods, permits and minimum effort before fieldwork.
• Survey all potentially affected pools and connected stream habitat using the approved method and document the area and effort actually completed.
• Submit confirmed records, negative survey results where required, locations, photographs, voucher information and survey effort to the relevant state or territory wildlife database.
• Report any new locality promptly to the relevant conservation authority because the species has a limited known distribution and its status is not fully defined.
• Use the current scientific name, Pingalla lorentzi, and identify the record as a fish observation rather than relying only on the common name.

Before habitat disturbance: Avoid and minimise habitat loss

The species is listed as Vulnerable in the Northern Territory and is known there only from the Finniss River. Before works, treat all suitable Finniss River habitat and connected freshwater habitat as potentially occupied until an approved assessment supports another conclusion.

Avoid direct disturbance to large pools, open stream sections, rock and sand substrates, and connected backwaters wherever practicable.

Retain natural flow paths and prevent changes to water quality, sediment movement, erosion and riparian vegetation that could affect pools used by the species.

Maintain aquatic connectivity between retained pools and stream reaches, and do not create barriers that prevent fish movement.

• Set project-specific no-go areas and waterway buffers through the aquatic ecological assessment and approval conditions.
• Keep machinery, stockpiles, fuels, concrete washout and spoil away from water and riparian areas.
• Stage unavoidable works so that the smallest practicable area of aquatic and riparian habitat is exposed at one time.
• Assess whether nearby parrots feather infestations require control, containment or hygiene measures, because fragments can spread through water, boats, wildlife and equipment.

Before habitat disturbance: Approvals and work planning

Confirm the EPBC Act position before works begin, noting that the supplied NT fact sheet states that Lorentz Grunter is not nationally listed under the EPBC Act.

Confirm the relevant state or territory status, permits and approval conditions, noting that the species is Vulnerable under the Northern Territory Territory Parks and Wildlife Conservation Act 1976.

Prepare a fauna and aquatic habitat management plan that identifies survey methods, authorised personnel, fish handling, water quality controls, incident response and reporting.

EPBC Act status: Not listed

Northern Territory status: Vulnerable under the Territory Parks and Wildlife Conservation Act 1976

• Obtain any required wildlife, fisheries, animal ethics, capture, relocation, waterway, threatened species and clearing approvals before capture or disturbance.
• Schedule works to avoid the November to February spawning period where the authority or project risk assessment identifies that as practicable.
• Use staged works and isolate only the approved work area, while retaining connected refuge habitat and suitable flow conditions.
• Brief all operators on the species, its identification, stop-work triggers, exclusion zones and reporting chain.

Before habitat disturbance: Pre-clearance preparation

Complete the approved pre-clearance aquatic survey immediately before disturbance and repeat it if water levels, flow or the work footprint changes materially.

Mark the approved disturbance boundary, retained pools, riparian vegetation, access routes, exclusion areas and any aquatic weed containment zones before machinery enters the site.

Use exclusion fencing, bunding or equivalent controls where they can protect retained aquatic habitat, provided they do not block fish passage or alter flow without approval.

• Install clean equipment and vehicle washdown controls before entering the catchment or moving between waterbodies.
• Remove or contain parrots feather only under an approved weed hygiene and disposal procedure, and prevent viable fragments from entering connected waterways.
• Check that the fauna spotter catcher and aquatic ecologist have the required authorisations, equipment and communication arrangements.
• Brief the crew on the requirement to stop and notify the environmental representative if a Lorentz Grunter or unidentified grunter is found.

During habitat disturbance: Daily controls and supervision

Works near water must be controlled each day because degradation of waterways, riparian vegetation, flow and water quality are identified threats. The fauna spotter catcher must work with the aquatic ecologist and machine operators under the approved management plan.

Inspect the work area at the start of each shift and after rainfall, flow changes, spills, equipment movement or any change to the approved footprint.

Keep sediment, turbid water, pollutants, concrete, fuels, spoil and plant material out of the waterway.

Maintain the approved flow path and prevent sudden drainage, dewatering or isolation of pools unless the method is authorised and supervised by the relevant qualified person.

• Keep a fauna spotter catcher or aquatic fauna specialist present whenever machinery could enter or affect aquatic habitat, where required by the management plan or approval.
• Use clear hand signals or radio contact so the spotter can stop machinery before it reaches water or retained habitat.
• Limit machinery access to marked routes and keep plant out of retained pools, stream beds, riparian vegetation and exclusion zones.
• Check and clean nets, boots, waders, pumps, boats and machinery before moving between waterbodies to prevent weed and aquatic fauna transfer.

During habitat disturbance: Fish and habitat handling

If fish must be captured, isolated or relocated, use the approved method and only personnel authorised under the relevant permit or approval.

Move any Lorentz Grunter only to suitable nearby retained habitat approved by the relevant authority, with comparable freshwater conditions and no barrier to movement.

Keep handling time short, protect fish from heat and abrasion, and maintain suitable water quality during temporary holding.

Treat logs, rocks, aquatic vegetation and bank material as habitat unless the aquatic ecologist has confirmed that removal is permitted and the material can be safely reinstated.

• Do not transfer water, sediment, aquatic plants or fish between catchments or waterbodies without approval.
• Use fish-safe screens on pumps and temporary water management equipment where required by the approved method.
• Inspect dewatered areas, isolated pools and equipment for stranded fish before disturbance resumes.
• Manage parrots feather fragments as a biosecurity risk and prevent them from being washed downstream.

During habitat disturbance: Finds, stop-work and records

Stop the relevant work immediately if a Lorentz Grunter is found in the disturbance area, if fish become stranded, or if water quality, flow or sediment controls fail.

Keep people and machinery clear while the authorised aquatic fauna personnel confirm identification and decide whether capture, release, relocation or another approved response is required.

Take photographs and record the location, date, time, habitat, water conditions, number of fish, size range, action taken and final destination.

Send injured fish to a suitably qualified aquatic wildlife rehabilitator, veterinarian or other authorised facility according to the project response plan.

Identification features: Silver body, dark dorsal scale margins, white stripe from below the eye to the upper lip, and a dark grey to blackish blotch on the anal fin

Recorded maximum length: About 20 cm

• Do not allow untrained workers to capture, retain, transport or relocate the fish.
• Notify the environmental manager and relevant regulator immediately when a listed fish is found or harmed, as required by the approval and incident plan.
• Record all stop-work events, captures, mortalities, injuries, releases, relocations, permit details and corrective actions.
• Resume work only after the authorised environmental representative confirms that the trigger has been resolved and controls are in place.

After habitat disturbance: Close-out checks

Post-work checks must confirm that no fish remain trapped, that waterway controls have worked and that retained habitat remains connected and suitable. Monitoring should address both the species and the threatening processes identified for the site.

Inspect the full work area, isolated pools, culverts, temporary channels, pump intakes and downstream margins for stranded, injured or dead fish before demobilisation.

Remove temporary barriers, bunds, screens and equipment only when doing so will not cause erosion, sudden flow change or fish stranding.

Check that banks, riparian vegetation, rock and sand substrates, pool connections and water quality controls have been restored or stabilised as required.

• Complete a final weed hygiene inspection and remove or contain parrots feather fragments and other aquatic plant material under the approved procedure.
• Photograph the completed site from fixed locations where practicable.
• Record outstanding defects, responsible persons, due dates and confirmation of close-out.

After habitat disturbance: Monitoring and reporting

Implement the monitoring program required by the approval, with emphasis on known or potentially occupied sites because the Northern Territory fact sheet identifies monitoring at known sites as a primary management priority.

Use repeat fish surveys and habitat inspections where the project affects pools, flow, riparian vegetation or water quality.

Compare post-work records with pre-work conditions for fish detections, pool connectivity, substrate, temperature, turbidity, aquatic vegetation and riparian condition.

• Submit survey results, incidents, mortalities, relocations, photographs, coordinates and habitat data to the relevant regulator and state or territory wildlife database.
• Report newly detected localities because further surveys are recommended to define the species distribution in the Finniss River and adjacent catchments.
• Keep records of weed treatment, equipment hygiene, erosion controls, water quality results and corrective actions.

After habitat disturbance: Ongoing obligations and offsets

Maintain exclusion zones, erosion controls, flow controls, weed hygiene and water quality measures for the period specified in the approval or management plan.

Review whether the completed works have caused residual loss or degradation of occupied or suitable habitat.

Apply any approved offset, rehabilitation or compensatory measure required by the decision-maker, and do not treat an offset as a substitute for avoiding or minimising direct impact.

• Escalate unplanned habitat loss, persistent turbidity, altered flow, new aquatic weed infestations or fish mortality to the project environmental manager and regulator.
• Continue monitoring until the approval criteria are met and retained habitat is stable.
• Update the fauna management plan when monitoring identifies a new risk or a control that is not working.

Rehabilitation actions: Restore aquatic and riparian habitat

Rehabilitation should restore the freshwater conditions used by Lorentz Grunter rather than provide only terrestrial revegetation. The target is connected, good-quality freshwater habitat with suitable pools, rock or sand substrates, open stream sections and functioning riparian margins.

Reinstate natural channel form, pool connections, flow paths and stable banks where works have altered them.

Use clean rock and sand substrates that match the local stream reach where substrate replacement is approved and necessary.

Revegetate disturbed riparian areas with locally appropriate native species selected by the project ecologist and land manager, while retaining some open, unshaded stream sections because the species is recorded in such habitat.

Do not introduce aquatic plants or move sediment, plants or water from another catchment without approval.

Target habitat: Large pools and connected lotic or lentic freshwater with rock or sand substrates

Water temperature recorded for adults: 25°C to 30°C

Riparian objective: Stable native vegetation that protects water quality without shading all open stream habitat

• Remove temporary barriers that interrupt fish passage once the site is stable and safe.
• Prevent erosion and sediment delivery to pools through stabilised banks, controlled drainage and staged revegetation.
• Retain or replace natural woody material and bank cover only where it supports the approved habitat design and does not obstruct fish passage.
• Design culverts, crossings and temporary diversions to maintain aquatic connectivity and suitable flow.

Rehabilitation actions: Control weeds and other pressures

Survey for parrots feather after rehabilitation and control new infestations before they form dense mats or spread into connected waterways.

Dispose of parrots feather and contaminated material so that fragments cannot regenerate downstream or be moved by machinery, boats, wildlife or water.

Maintain erosion, pollution and flow controls because these are identified potential threats to Lorentz Grunter habitat.

• Use clean equipment when entering restored pools and stream reaches.
• Inspect downstream pools after high flows or storm events for transported weed fragments, sediment and altered flow.
• Coordinate weed control with the aquatic ecologist so treatment does not harm fish or degrade water quality.
• Manage fire and riparian disturbance in accordance with the approved catchment or site plan, noting that altered fire regimes are identified as a potential threat but no species-specific fire prescription is provided.

Rehabilitation actions: Monitor success

Monitor fish use, pool connectivity, water quality, bank stability, substrate condition, riparian recovery and aquatic weed presence at the frequency and duration required by the approval.

Repeat approved fish surveys during suitable conditions and include the November to February spawning period and September juvenile period where the monitoring design and authority permit.

Treat rehabilitation as successful only when the approved criteria are met, including stable habitat, functioning connectivity, acceptable water quality and no continuing spread of parrots feather.

Spawning period to consider in monitoring: November to February

Juvenile observation period to consider in monitoring: September

• Record Lorentz Grunter detections with coordinates, habitat description, survey effort, photographs and fish size where safely obtained.
• Investigate any failure to detect expected habitat recovery, fish stranding, mortality, persistent turbidity, altered flow or weed recurrence.
• Submit monitoring results and any new records to the regulator and relevant state or territory wildlife database.
• Continue corrective actions until the site meets the approved rehabilitation and monitoring requirements.

Sources

• Threatened species of the Northern Territory, Northern Territory Government: https://nt.gov.au/__data/assets/pdf_file/0004/1344532/lorentz-grunter.pdf
• Pingalla lorentzi, Lorentz's grunter, fishbase.se: https://www.fishbase.se/summary/Pingalla-lorentzi
• Parrots feather NT Weed Risk Assessment Technical Report, Northern Territory Government: https://denr.nt.gov.au/__data/assets/pdf_file/0004/258016/wra-report-parrots-feather-updated-logo.pdf