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Scalloped Hammerhead (Sphyrna lewini)

The Scalloped Hammerhead is a coastal and semi-oceanic shark found in warm temperate and tropical seas. In Australia it occurs from Western Australia around the tropical north to New South Wales, using coastal and offshore waters, continental shelves and shallow nursery areas.

Conservation status

Commonwealth, EPBC Act 1999: Conservation dependent.

Victoria, Flora and Fauna Guarantee Act 1988: Conservation dependent.

Queensland, Nature Conservation Act 1992: Endangered.

Seasonal planning

In northern Australia, breeding occurs in February and March, while births in Australia occur around October to January.

Seasonal evidence: From published sources for this species.

Timing varies between sites and years.

  • Breeding and birth season: In northern Australia, breeding occurs in February and March, while births in Australia occur around October to January.

Identification: Appearance

A large hammerhead shark with a broad head that has a prominent central indentation and smaller notches near the eyes. Its head is 24 to 30% of its total length, and it is grey-brown above and white underneath.

A large hammerhead shark with a broad head that has a prominent central indentation and smaller notches near the eyes. Its head is 24 to 30% of its total length, and it is grey-brown above and white underneath.

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, the species is recorded in New South Wales, Queensland, the Northern Territory and Western Australia. It occurs from about Geographe Bay in Western Australia, around northern Australia, south to Sydney.

In Australia, the species is recorded in New South Wales, Queensland, the Northern Territory and Western Australia. It occurs from about Geographe Bay in Western Australia, around northern Australia, south to Sydney.

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

This coastal and semi-oceanic pelagic shark occurs over continental and insular shelves, in nearby deep water and from the intertidal zone to at least 275 m. Adults may use deeper offshore waters, while juveniles are found close to shore in shallow nursery habitats.

This coastal and semi-oceanic pelagic shark occurs over continental and insular shelves, in nearby deep water and from the intertidal zone to at least 275 m. Adults may use deeper offshore waters, while juveniles are found close to shore in shallow nursery habitats.

Foraging habitat: Diet

Prey includes bony fishes, sharks, rays and invertebrates.

Prey includes bony fishes, sharks, rays and invertebrates.

Breeding habitat: Breeding

Adult females occupy deeper water and move into shallower water to mate and give birth. The species bears litters of 14 to 26 pups.

Adult females occupy deeper water and move into shallower water to mate and give birth. The species bears litters of 14 to 26 pups.

Sheltering habitat: Shelter

Young sharks occur in shallow muddy areas. Bays and mangroves provide shallow coastal shelter for juveniles.

Young sharks occur in shallow muddy areas. Bays and mangroves provide shallow coastal shelter for juveniles.

Threats: Threats

Commercial and illegal fishing are identified as risks, as the species forms large aggregations and is vulnerable to fishing.

Commercial and illegal fishing are identified as risks, as the species forms large aggregations and is vulnerable to fishing.

Survey methodology: 1. Commonwealth guidance

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

For EPBC Act referrals, survey effort and methods should be consistent with the survey guidelines for Australia's threatened fish, read with the Significant impact guidelines 1.1.

Survey methodology: 2. 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