Australian lungfish
The Australian lungfish (Neoceratodus forsteri) is listed under the EPBC Act as vulnerable and a
recovery plan has been drafted (DCCEEW, 2017).
It is also a no-take species under the Fisheries Act 1994. The species was eligible for listing as vulnerable given (DotE, 2014): as a result of past changes to its core habitat, it is suspected that the recruitment to the adult breeding population has been, and is still, unsustainably low; and that the species is likely to undergo a substantial population reduction over the next three generations.
The species also has a limited geographic distribution that is precarious for its survival. Its area of occupancy is estimated to be less than 2,000 km2 and continued decline in quality and extent of spawning and nursery habitat is likely as further water infrastructure development occurs in this populated area of Queensland.
The Australian lungfish is a large and elongated freshwater fish which can reach a maximum size of approximately 150 cm in length and 48 kg in weight.
The Australian lungfish is one of only six lungfish species in the world and is considered to be one of the oldest known extant vertebrate species.
Diet
Adult Australian lungfish are suctorial feeders and consume large amounts of material such as plant
matter and sand that they do not digest (Spencer, 1892).
Adults have crushing plates and, in captivity,
would eat fish, insect larvae, molluscs, tadpoles, crustaceans (such as Macrobrachium spp.) and
aquatic vegetation such as Vallisneria spp. and Hydrilla spp. making them low level benthic carnivore.
Juvenile and hatchling lungfish are active predators and consume small invertebrates such as tubifex worms and water fleas.
The Australian lungfish are nocturnal foragers, with the ability to detect prey via electroreception
which allows lungfish to sense electric fields generated by prey.
Within Mary River adults have been noted to predominately forage within macrophyte beds in water less than 2 m deep.
Juveniles are
ambush predators using aquatic macrophytes as cover to catch prey.
Habitat
The Australian lungfish requires clear or turbid, low-flow or still, vegetated, shallow pools to support spawning and feeding..
Macrophytes are essential for reproduction with submerged or emergent variants providing nesting surfaces for egg laying and
refuges for juveniles.
Adult lungfish favour submerged logs, dense banks of aquatic vegetation, or underwater caves
formed by bed scouring under submerged logs. While lungfish can be found in both pools and riffles, their preferred habitats are pools of 3-10 m depth. In habitats such as these, they can often live in large groups.
All lungfish under 500 mm in length collected by Brooks and Kind (2002) were caught in dense macrophyte growth favoured for spawning, suggesting that juveniles prefer the same habitat and are probably slow to disperse after hatching.
