Great hammerhead
Sphyrna mokarran
Illustration: Bloom by Day
PROTECTED — look, don't shoot
The biggest hammerhead, pale grey and bronzy, its head almost straight across the front and its first dorsal very tall and pointed — a sail rather than a fin. Usually alone, usually deep, and usually gone before you have decided which hammerhead it was.
how to recognise it
- the front edge of the hammer is almost straight in adults, with a slight notch in the middle
- a very tall, curved first dorsal fin with a pointed tip
- second dorsal and pelvic fins also high, with deeply concave rear edges
- pale grey to bronzy greyish-brown, white below, with no conspicuous fin markings
- very large — the biggest of the hammerheads
don’t confuse with
- Scalloped hammerhead — the scalloped hammerhead has a forward-curved head notched in the middle, and a shorter, more curved first dorsal
Field marks read from Fishes of Australia, 2026-10-15. Our wording, their facts. Max size 610 cm TL.
facts
- habitat
- pelagic
- size
- ~350 cm, to 610 cm
Max size from Fishes of Australia (610 cm TL); the typical size is Bluebird’s, not from a cited source
- records
- 7420 at 22 spot(s), none of
them in this region
Recorded at Low Isles (Port Douglas), Green Island (Cairns), Dunk Island (Mission Beach), Hinchinbrook Island — Ramsay Bay, Magnetic Island — Geoffrey Bay, Border Island (Whitsundays — East), Cid Harbour (Whitsunday — West), Cairns Reef (Great Barrier), Heron Island (GBR), Lady Elliot Island (GBR), Fraser Island — Kingfisher Bay (West), Jew Shoal (Sunshine Coast), Bray Rocks (SC), Kings Beach (Caloundra), Fly Point (Nelson Bay), Shoal Bay (Port Stephens), Seal Rocks (NSW), Shark Point (Clovelly), Shelly Beach (Manly), Gordon's Bay (Sydney), Bare Island (La Perouse), Magic Point (Maroubra). A count of occurrence records, not abundance. Records are where someone looked.
when it has been recorded
JFMAMJJASOND
A gap means no record in the sample, not absence.
the rule
QLD — No take
source
· verified 2026-10-10
NSW — No take
source
· verified 2026-10-01
no closed season recorded for this species — that is not the same as open; check the official page
Rules checked 2026-10-13 against qld.gov.au
Rules change. Check before you dive.
Occurrence data: Atlas of Living Australia (ala.org.au), CC-BY 4.0.
Diver transect counts: Reef Life Survey (reeflifesurvey.com), CC-BY 4.0, supplied via ALA.
Target and protected species: Queensland tidal-water size and possession limits (qld.gov.au) and NSW saltwater bag and size limits plus threatened species lists (dpird.nsw.gov.au).
Habitat and size: Bluebird, approximate, from general knowledge. Not cited. FishBase is CC BY-NC and this app is commercial, so it is not used.
Description written for Bloom. RECORDS ARE WHERE SOMEONE LOOKED, NOT WHERE THE FISH ARE. A record count is a count of records near here and nothing else -- it is not abundance, and a species with few records is not rare. Absence of records is not absence of fish.
Diver transect counts: Reef Life Survey (reeflifesurvey.com), CC-BY 4.0, supplied via ALA.
Target and protected species: Queensland tidal-water size and possession limits (qld.gov.au) and NSW saltwater bag and size limits plus threatened species lists (dpird.nsw.gov.au).
Habitat and size: Bluebird, approximate, from general knowledge. Not cited. FishBase is CC BY-NC and this app is commercial, so it is not used.
Description written for Bloom. RECORDS ARE WHERE SOMEONE LOOKED, NOT WHERE THE FISH ARE. A record count is a count of records near here and nothing else -- it is not abundance, and a species with few records is not rare. Absence of records is not absence of fish.