Shorthead Lamprey

Mordacia mordax
Shorthead Lamprey - Marinewise © 2025 MarineWise

Quick Facts

Scientific name Mordacia mordax
Other names Murray Lamprey
Size Up to 56 cm (22 in)
Weight Under 1 kg (2.2 lb)

Distribution

Habitat & AU Distribution Fresh & marine waters in coastal rivers, streams & other water ways connected to the sea
Depth Range 0 - 10 m (33 ft)
Shorthead Lamprey Distribution

Interesting Info

  • The Shorthead Lamprey is a primitive, eel-like fish that are found in coastal rivers and estuaries from southern Queensland through New South Wales, Victoria, Tasmania, and eastern South Australia.
  • It belongs to the jawless fish group (Agnatha), which split from other vertebrates millions years ago — making lampreys true “living fossils.”
  • Their bodies are long, slim, and scaleless, coloured blue-grey to brown on top and silvery below, with no paired fins.
  • They lack jaws — instead, they have a round, sucker-like mouth lined with sharp keratin teeth used to latch onto other fish.
  • They prefer rivers with clean gravel beds and good flow, which provide suitable spawning habitat.
  • Despite their gory feeding style, lampreys rarely kill their hosts and are an important part of the marine food web.
  • Adults return to rivers to spawn, completing a catadromous life cycle (opposite of salmon, which are anadromous).
  • Breeding occurs in freshwater rivers during winter and spring. Adults stop feeding, migrate upstream, and spawn in gravel nests before dying — they are semelparous (breed once, then die).
  • Eggs hatch into worm-like larvae called ammocoetes, which bury themselves in river silt and filter-feed on plankton and detritus for 3–4 years.
  • After metamorphosis, juveniles migrate downstream to the sea, where they become parasitic, attaching to larger fish and feeding on their blood and body fluids.
  • Lifespan is around 6–8 years, with most of that time spent in the larval stage.
Species Interaction

Recreational Fishing, Conservation & Research

The shorthead lamprey is not a targeted species for recreational fishing. It is however, an important traditional food source and may be harvested for subsistence or cultural purposes with some Indigenous communities. Their greatest value is ecological and scientific: they are an ancient lineage that helps researchers understand vertebrate evolution, and their migrations highlight the importance of maintaining fish passage past dams and weirs.

Scientific Classification

Kingdom: Animalia

Phylum: Chordata

Class: Hyperoartia

Order: Petromyzontiformes

Family: Mordaciidae

Genus: Mordacia

Species: Mordacia mordax

Conservation Status

The conservation status of the shorthead lamprey varies depending on the state or territory where it is found. In Victoria, the species is listed as “vulnerable” under the Victorian Flora and Fauna Guarantee Act 1988. In Tasmania, the species is considered to be “rare” under the Tasmanian Threatened Species Protection Act 1995, and in South Australia, it is listed as “near threatened” under the National Parks and Wildlife Act 1972. However, in New South Wales, the shorthead lamprey is not considered to be a threatened species.

Fish Taste Quality

Shorthead lamprey is not a widely consumed or highly valued food fish, and is not typically considered to be of high culinary quality.

Taste Rating: 1/5

How to catch
Shorthead Lamprey

Catch Difficulty: Easy

Tackle: Fish Trap

Bait: Fresh cut flesh baits

Technique: Bait in a fish trap

Popularity: Targeted