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Dusky Sea Snake (Aipysurus fuscus)

The Dusky Sea Snake is a marine snake found on offshore reefs in the Timor Sea off Western Australia. It is associated with shallow coral reefs, which provide important habitat for prey and shelter.

Conservation status

Commonwealth, EPBC Act 1999: Endangered.

Western Australia, Biodiversity Conservation Act 2016: Endangered.

Commonwealth, EPBC Act 1999: Listed marine. A listed marine species under Part 13 of the EPBC Act. Killing, injuring, taking or moving it in a Commonwealth area needs a permit.

Seasonal planning

No species-specific activity or breeding months were found in the published sources used. Use the following as a works-planning prompt, not as seasonal biology.

Seasonal knowledge: Not documented in the sources used.

The month values are a general planning prompt only and do not represent known activity or breeding months for Aipysurus fuscus.

  • Plan checks before disturbance: General planning window only. Check the work area before disturbance whenever works are scheduled.

Identification: Appearance

It is a relatively small brown or purple-brown sea snake, sometimes with faint cross-bands. Adults can reach about 90 cm in total length.

It is a relatively small brown or purple-brown sea snake, sometimes with faint cross-bands. Adults can reach about 90 cm in total length.

Identification: Confirming identity

Confirm the identity of any suspected record with a specialist and a photograph or voucher, as required by the relevant permit.

Distribution: Known range

In Australia, it is associated with offshore reefs of the Sahul Shelf in the Timor Sea off Western Australia. Records include Ashmore, Hibernia, Scott and Seringapatam reefs, as well as Cartier Island.

In Australia, it is associated with offshore reefs of the Sahul Shelf in the Timor Sea off Western Australia. Records include Ashmore, Hibernia, Scott and Seringapatam reefs, as well as Cartier Island.

Distribution: National mapping

The Commonwealth species distribution model (SNES) maps where the species or its habitat is known, likely or may occur. Use it with local records and site inspection.

Habitat: Habitat

It inhabits shallow, emergent coral reefs, generally at depths under 15 m. It has been observed among moderate to heavy coral growth and in sandy-bottomed gullies and channels.

It inhabits shallow, emergent coral reefs, generally at depths under 15 m. It has been observed among moderate to heavy coral growth and in sandy-bottomed gullies and channels.

Foraging habitat: Diet

It feeds mostly on wrasses (Labridae); fish and occasionally fish eggs are also reported in its diet.

It feeds mostly on wrasses (Labridae); fish and occasionally fish eggs are also reported in its diet.

Breeding habitat: Breeding

The species is ovoviviparous.

The species is ovoviviparous.

Sheltering habitat: Shelter

Coral reefs provide important shelter for the Dusky Sea Snake.

Coral reefs provide important shelter for the Dusky Sea Snake.

Threats: Threats

Loss of live coral has been identified as a possible contributor to declines at some locations.

Loss of live coral has been identified as a possible contributor to declines at some locations.

Threats: Works risk

Works that damage or remove live coral could affect habitat on which the species depends for prey and shelter. Activities that disturb coral reef habitat may therefore affect its access to these resources.

Survey methodology: 1. Species-specific methods

Use methods consistent with the Commonwealth survey guidelines and engage a specialist with the right permits.

Surveys have recorded the species in shallow water under 10 m and in the 12 to 25 m depth zone.

Survey methodology: 2. Commonwealth guidance

For EPBC Act referrals, survey effort and methods should be consistent with the ePBC Act publications, including the National Guidelines for the Survey of Cetaceans, Marine Turtles and the Dugong (2024), read with the Significant impact guidelines 1.1.

Survey methodology: 3. Limits

A non-detection is not proof of absence. Match survey timing to the species and season, and record effort.

Vegetation associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific vegetation association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Ecosystem associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific ecosystem association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Soil and substrate associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific soil association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Water and wetland associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific water association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Fauna records and mapped habitat: Not yet analysed

Record locations can be overlaid with mapping, but record frequency alone does not measure habitat preference. No species is excluded from desktop assessments by this analysis.

No quality-controlled record-to-map analysis has been completed for this species. The existing generalised distribution dots and indicative range polygons have not been treated as precise occurrence coordinates.

A defensible run needs dated, independently attributable records, coordinate uncertainty, duplicate and captive-record checks, layer versions and regional scope. Preference and absence require additional survey-effort and detection evidence.

Habitat limitations and contrary evidence: No supported exclusion recorded

Not recorded is not the same as cannot occur. Low suitability, resident habitat, breeding habitat and occasional movement are different conclusions.

This library has not established a vegetation, ecosystem or soil-type exclusion for this species. This does not mean all habitat is suitable; the evidence needed to justify an exclusion has not been assembled.

Habitat limitations and contrary evidence: Before using a negative association

  • Confirm the taxon, geographic region, life stage and habitat function covered by the evidence.
  • Check survey methods, season, repeated effort and detectability before interpreting non-detection.
  • Investigate credible contradictory records and microhabitats absent from broad mapping.
  • Do not convert a missing map class, low record count or failed data request into species absence.

Before disturbance: 1. Desktop and approvals

Confirm whether the project could affect the species before works begin.

Check national mapping, state records and recent surveys for the site. An action likely to have a significant impact on this nationally listed species needs EPBC Act referral, and state permits apply where it is state listed.

Before disturbance: 2. Plan to avoid

Plan in-water works, vessel movements and lighting to avoid known habitat and sensitive periods, and set observer and shutdown procedures before works start.

During disturbance: 1. Controls

Keep works inside the approved footprint and conditions.

Use spotters and exclusion zones for in-water works and vessels, and pause works if the species is seen within the zone.

During disturbance: 2. Stop and report

If the species is found unexpectedly, stop work at that spot and contact the project ecologist and the relevant agency.

After disturbance: 1. Records

Record outcomes.

Record sightings, habitat lost or retained and any injury or death, and report them under the approval conditions.

Rehabilitation: 1. Restore

Restore disturbed habitat where possible.

Remove temporary structures, restore natural flow and substrate, and monitor water quality until it returns to baseline.

Sources