Species Profile and Threats Database

For information to assist proponents in referral, environmental assessments and compliance issues, refer to the Policy Statements and Guidelines (where available), the Conservation Advice (where available) or the Listing Advice (where available).
In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.

EPBC Act Listing Status Listed as Endangered as Maccullochella mariensis
Recovery Plan Decision Recovery Plan required, this species had a recovery plan in force at the time the legislation provided for the Minister to decide whether or not to have a recovery plan (19/2/2007).
Adopted/Made Recovery Plans The Mary River Cod Research and Recovery Plan - 1996-2001 (Simpson, R. & Jackson, P., 1996) [Recovery Plan] as Maccullochella mariensis.
Policy Statements and Guidelines Survey guidelines for Australia's threatened fish. EPBC Act survey guidelines 6.4 (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2011i) [Admin Guideline].
Federal Register of
    Legislative Instruments
Declaration under s178, s181, and s183 of the Environment Protection and Biodiversity Conservation Act 1999 - List of threatened species, List of threatened ecological communities and List of threatening processes (Commonwealth of Australia, 2000) [Legislative Instrument] as Maccullochella peelii mariensis.
Amendment to the list of threatened species under section 178 of the Environment Protection and Biodiversity Conservation Act 1999 (119) (01/08/2011) (Commonwealth of Australia, 2011e) [Legislative Instrument] as Maccullochella mariensis.
Scientific name Maccullochella mariensis [83806]
Family Percichthyidae:Perciformes:Actinopterygii:Chordata:Animalia
Species author (Rowland, 1993)
Infraspecies author  
Reference Nock, C.J., Elphinstone, M.S., Rowland, S.J. & Baverstock, P.R. (2010). Phylogenetics and revised taxonomy of the Australian freshwater cod genus, Maccullochella (Percichthyidae). Marine and Freshwater Research 61:980-991
Other names Maccullochella peelii mariensis [64680]
Distribution map Species Distribution Map

This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.

Illustrations Google Images

Scientific name: Maccullochella mariensis

Common name: Mary River Cod

The Mary River Cod was not formally recognised as distinct from the Eastern Cod Maccullochella ikei and the Murray Cod Maccullochella peelii, until the subspecies was described in 1993 (Rowland 1993). The Mary River Cod differs from the Murray Cod by the combination of a deeper and shorter caudal peduncle (the region of the body between the end of the anal fin and the base of the caudal fin), longer pelvic fins, larger sagittal otoliths (part of the inner ear) and lesser extension of the first anal pterygiophore (the internal cartilage or bone that supports a median fin ray) towards the first caudal vertebra. It differs from the Eastern Cod by the combination of a deeper caudal peduncle, greater postorbital head length, smaller orbit, larger interorbital width, fewer scale rows behind the lateral line, shorter fifth-sixth dorsal spines and lesser extension of the first anal pterygiophore (Rowland 1993).


Two forms of this species, designated 'sharp-nose' and 'boof-headed', were recognised by fisherman from the Mary River system (Winkel 1982, as cited in Merrick & Schmida 1984). 'Boof-headed' forms tend to be spotted, and 'sharp-nosed' forms mottled. Rowland (1993) did not find that there are two different morphological forms, but spotted markings and possibly a blunter snout are probably features of older fish (G. Cook, as cited in Simpson & Jackson 1996). This species may be identical to the species that once occurred in the Brisbane River, Logan River, Albert River and Coomera River drainages (Wager & Jackson 1993).

The Mary River Cod is a yellowish to pale green fish. Formerly, cod as large as 23.5 kg (and anecdotally up to 38 kg) were caught. Today, cod larger than 5 kg and 70 cm are uncommon (Simpson & Jackson 2000). It has dark heavily reticulated mottling on the back and sides, sometimes extending onto the belly. The belly is grey-green to whitish. The fins are clear to dark with grey-green mottling on bases, with whitish margins (McDowall 1996).

According to local residents, anglers, foresters and fish hatchery workers, the Mary River Cod disappeared from (or became extremely rare in) the main channel of the Mary River around Conondale, Kenilworth, and Gundiah in the 1950s, from Munna Creek in the 1950s, from Yabba Creek and Munna Creek the 1960s, and from Booloumba Creek in the 1970s. A single cod caught in Yabba Creek by Simpson (1994) was thought to be a stocked fish from Borumba Dam, rather than part of a remnant population from the creek. The range of the cod within Tinana and Coondoo Creeks is around 70 km. It is estimated that the subspecies now occurs in less than 30% of its former known range in the Mary River system (Simpson & Jackson 2000).

The length of the creek occupied by Mary River Cod within Tinana and Coondoo Creeks is 17 to 21 km, the length occupied within Six Mile Creek is around 20 km, and the length occupied in Obi Obi Creek is around 10 km (Simpson & Jackson 2000). Therefore, the total length of stream where the subspecies is regularly found is 51 km. As the maximum stream width is around ten to 15 m, the main area of occupancy is between 5 km² and 7.5 km².

The Mary River Cod has been stocked in impoundments for recreational angling since 1983. Official stocking sites are Baroon Pocket Dam, Borumba Dam, and Lake Macdonald in the Mary River catchment, Wivenhoe Dam, Somerset Dam, Cressbrook Dam, and Moogerah Dam in the Brisbane River catchment, Hinze Dam on the Nerang River, Maroon Dam on the Albert-Logan River, and Lake Samsonvale on the North Pine River. According to reports in the 1950s and 1960s, the Mary River Cod may also have been introduced to the Dawson River, but it does not occur there now (Simpson & Jackson 2000).

The Mary River Cod occurs in three natural subpopulations (Lake Macdonald, Tinana Creek and Coondoo Creek upstream of Tinana Barrage, and upper Obi Obi Creek) in different tributary systems, isolated from one another by impoundments and the main river channel (Simpson & Jackson 2000).

Simpson has extensively surveyed the stream habitat and undertaken fishing surveys of the Mary River Cod within the Mary River (1994).

The total estimated number of Mary River Cod in Tinana-Coondoo Creek, Six Mile Creek and Obi Obi Creek is fewer than 600 individuals (Simpson & Jackson 2000).

Tinana-Coondoo and Six Mile Creek each support around 250 Mary River Cod, and Obi Obi Creek supports around 50 to 70 (Simpson & Jackson 2000).

The population size of the Mary River Cod has declined severely since the early 1900s, when it was common in the Mary River system (Rowland 1993; Simpson & Jackson 1996).

Fishing is banned in two sections of Tinana-Coondoo Creek (totalling 6 km) and one section of Obi Obi Creek (4 km between the Baroon Pocket Dam and Skenes Creek) (Simpson & Jackson 2000).

Water characteristics
The Mary River Cod occurs mainly in pools within relatively undisturbed tributaries (Wager & Jackson 1993). Cod prefer relatively large and deep (0.8 to 3.2 m) shaded pools with abundant, slowly flowing water (Simpson & Jackson 2000). Simpson (1994) found that tributaries were cooler than the main channel of the Mary River, especially Six Mile Creek. According to a radio-tracking study by Simpson & Mapleston (2002), the 95% of locations of Mary River Cod were in water between one and 3 m deep, and the fish strongly avoids shallow areas (Simpson 1994). Cod were frequently found immediately downstream of a constriction of the stream (e.g. a riffle) where food was presumably concentrated by the water flow. Physiochemical parameters such as pH, conductivity, dissolved oxygen content and turbidity varied widely. Mary River Cod appear to tolerate a wide range of conditions (Simpson 1994). The flow regime of the Mary River and its tributaries is naturally highly variable, and the timing and duration of flow changes is unpredictable through the year (Pusey et al. 1993). Mary River Cod tolerate high gradient upland stream habitats as well as slow-flowing lower reaches (Simpson & Jackson 2000). The habitat of hatchlings and juveniles is poorly known. In the closely-related Murray River Cod, larvae do not shelter in shallow backwaters, but remain in the channel and disperse widely by drifting for around one to two weeks (Humphries 2005; Koehn & Harrington 2005). They appear to move into the current at night, when they drift downstream to new pools (King 2004). Preliminary observations suggest that one and two-year-old fish use shallow, flowing reaches more than adults do (Simpson & Mapleston 2002).

Mary River Cod use submerged logs and branches (snags) as cover from which to ambush prey, as resting sites, and as nesting sites. Branches, logs and submerged vegetation also provide habitat for prey, including invertebrates that are eaten by juvenile fish, although too much debris can reduce water quality (Simpson 1994). Simpson & Mapleston (2002) radio-tracked nine adult Mary River Cod in Tinana Creek, Condoo Creek and Six Mile Creek. Ninety-five percent of 344 radio-tracking locations were within 2m of large woody debris (44% in logpiles, 32% next to large single logs, 12% in single logs next to undercut banks, and 7% next to small logs or branches). Cod rarely used undercut banks without woody debris, and rarely used rocks. Although open water formed 72% of the habitat, cod were only found in open water in 4% of locations. Logpiles were the most preferred habitat. Large snags of the type used by cod persist for long periods in the Mary River, and tend not to be displaced by floods (Pusey et al. 1993). Simpson (1994) surveyed habitat throughout the Mary River system and found that submerged cover was more common in tributaries than in the main river channel, and that it was most abundant (24% to 32%) at Tinana-Coondoo Creek, Six Mile Creek, and Glastonbury Creek.

Habitat in Tinana-Coondoo Creek
Tinana Creek, and its branch, Coondoo Creek are relatively long, low gradient streams (Simpson 1994). They are surrounded by pine plantations which have buffer strips of tall native vegetation along the creeks, and some areas of native forest. The riverside vegetation provides shading and cover such as logs, logpiles, branches and overhanging vegetation. There are large, deep, permanent pools throughout Coondoo Creek and in Tinana Creek below the junction with Coondoo Creek. The stream beds are fine sand or mud. In contrast to many other parts of the Mary River, these streams have not been degraded by siltation. Around 17 to 21 km of the creeks consist of pools suitable as permanent habitat for Mary River Cod (25% to 30% of the range of the subspecies within these creeks).

Habitat in Six Mile Creek
Six Mile Creek is a relatively long, low gradient stream with mainly shallow pools of less than 2 m average maximum depth (Simpson 1994). It is surrounded by cleared agricultural land, but the riverside vegetation is generally in good condition, so it provides abundant shade and cover. There are long stretches of riffle and run habitat between pools. The stream beds are fine sand or mud, and the banks are steep. Around 20 km of the creeks consist of pools suitable as permanent habitat for Mary River Cod (50% of the range of the subspecies within this creek). Lake Macdonald is a reservoir supplying drinking water, 55 km from the junction of the creek with the main channel of the Mary River. It reduces the downstream flows into Six Mile Creek (Simpson & Jackson 2000).

Habitat in Obi Obi Creek
Obi Obi Creek is a relatively short, high gradient creek with many runs, riffles and glides of flowing water. It contains some of the deepest pools in any of the Mary river tributaries (Simpson 1994). The floodplains around the downstream section of Obi Obi Creek are farmland, and the cod is now very rare or absent in this part of the creek. The upstream section as far as Baroon Pocket Dam is surrounded by steep rocky gorges, including Obi Obi Gorge National Park. The stream bed is rock, and there is little woody debris or overhanging vegetation. The dam has resulted in some siltation of the creek.

The Mary River Cod appears to mature at a length of about 38 cm (Merrick & Schmida 1984). It is a large, long-lived and slow growing fish with relatively low fecundity and a long generation period (Rowland 1985; Rowland 1993). In fish hatcheries, males may be sexually mature when they reach a size of 30 cm, and most Mary River Cod that are longer than 50 cm and weigh more than 2 kg are sexually mature (Cook, as cited in Simpson & Mapleston 2002).

Most information on reproduction in the Mary River Cod comes from captive fish in hatcheries. In hatchery ponds, it spawns annually between August and October. Females probably produce around 2000 eggs per kilogram. Some females may spawn more than once in a season. The male selects and guards the nest site, which is a hollow pipe or purpose-built nesting box in hatchery ponds (Simpson & Jackson 2000). Spawning takes place soon after the water temperature rises to 20°C (Harris & Rowland 1996), and may involve aggression between pairs (Simpson & Jackson 2000). In the wild, where cool water temperatures persist for longer than in hatcheries, spawning may take place as late as December. Mary River Cod do not migrate in relation to spawning, and they are less active during the spawning season than at other times. They are particularly active preceding spawning, when they are selecting nest sites and defending territory boundaries (Simpson & Mapleston 2002).

Wild Mary River Cod use hollow logs as spawning sites (Simpson & Mapleston 2002). They deposit the eggs as a layer, where they adhere to the hard surface inside the pipe or log. They are sometimes scattered around the nest site following fighting. The opaque eggs, measuring three to 3.5 mm in diameter, are guarded by the male. Hatching commences towards the end of the fourth day at 20°C, and is usually completed by the end of the seventh day. Newly hatched cod larvae are five to 7 mm long (Simpson & Jackson 2000). The male continues to guard the brood until they disperse and start feeding around seven to nine days after hatching.

Large Mary River Cod (weighing more than 3.6 kg) eat mainly fish. Small cod eat crustaceans (Winkel 1982, as cited in Merrick & Schmida 1984) such as yabbies and shrimp (Simpson & Jackson 2000). There are also reports of small birds, bats and water rats in the stomach contents of angled specimens (Simpson & Jackson 2000). Larvae feed on zooplankton and aquatic insects, especially chironomid larvae (Harris & Rowland 1996). Newly hatched captive-bred cod eat plankton and brine shrimp. (Simpson & Jackson 2000).
The Mary River Cod is an ambush predator which feeds most actively around dusk and dawn (Simpson & Mapleston 2002).

Simpson & Mapleston (2002) radio-tracked nine Mary River Cod for 20 months in two tributaries of the Mary River: Tinana-Coondoo Creek and Six Mile Creek. Some fish remained in their home ranges all year. Feeding and patrolling movements within the home range are most common from dusk to dawn. Cod typically moved in short bursts between logs and logpiles within their home range, following no particular route.

At irregular times, some Mary River Cod left their usual home ranges and moved rapidly for long distances in one direction. These fish typically moved more than 10 km in one to three weeks. This long-distance movement usually occurred during floods, and the distance that Mary River Cod moved per month was correlated with water flow rate. The three longest upstream movements occurred in February (the wet season), and the three longest downstream movements in May. Long-distance movements were unpredictable and unsynchronised; no more than three fish moved at the same time and they sometimes moved in opposite directions during a flood. Six of nine radio-tagged fish made at least one such movement during the study of twenty months, and one did five times. Five of them returned to their usual home ranges after three to nine months, and three returned to the same particular snag or logpile where they had previously sheltered (Simpson & Mapleston 2002).

It had previously been suggested that Mary River Cod in the main river channel left in August to move upstream into smaller tributaries where they stayed during spring and summer until April, when they moved back into the main river (Winkel 1982, pers. comm. in Merrick & Schmida 1984). Simpson & Mapleston (2002), found is no scientific evidence to support this idea.

Effect of dams on movement patterns
The potential for movement of Mary River Cod has been limited by large dams, such as the Borumba, Baroon Pocket, and Lake Macdonald Dams, weirs such as the Gympie, Teddington, and Tallegalla weirs, the Mary River and the Tinana Creek tidal barrage, and numerous culverts and road crossings (Simpson & Jackson 2000). Simpson & Mapleston (2002) found that radio-tagged Mary River Cod did not move within 15 km of barriers (Lake Macdonald and Tallegalla Weir).

The Mary River Cod is territorial. Between periods of movement, it occupies a particular home range for up to several years. Home ranges are 70 to 1000 m long, and usually include two to four core areas where the fish spends a large proportion of its time. Home range size is not related to the size of the fish, and does not change seasonally (Simpson & Jackson 1996; Simpson & Mapleston 2002).

Recreational fishing
The Mary River Cod has been heavily fished in the past, and this has been one cause of its decline (Rowland 1993). Gelignite, nets and set lines were used intensively in the late 1800s and early 1900s to kill large numbers of cod (Simpson & Jackson 2000). Fishing for Mary River Cod within the Mary River catchment is now prohibited, but the large areas of State Forest in the Tinana-Coondoo catchment and the rugged gorge area surrounding Obi Obi Creek make enforcement difficult. There is evidence of continued fishing pressure on the Mary River Cod (Simpson & Jackson 2000). Of nine cod radio-tracked by Simpson & Mapleston (2002), one was probably illegally caught and killed by an angler. There may be substantial mortality associated with the catch and release methods of angling for this species (Simpson 1994).

Habitat degradation
The clearing of timber from the Mary River and its banks for agricultural development has caused erosion. Grazing and disturbance of banks by cattle inhibits the regeneration of native vegetation (H.S. Midgley, as cited in Rowland 1993). Damage to the banks has caused extensive siltation and filling of pools in the main channel of the river. According to local residents, the mid-reaches have been nearly constantly turbid (muddy) only since the 1970s (J. Cann, as cited in Cogger et al. 1993; Cann & Legler 1994). Stream channels are also damaged and the water turbidity increased by sand and gravel mining, which occurs in many parts of the Mary River both above and below the water line, particularly upstream of Gympie (Pusey et al. 1993; Simpson 1994; Wager & Jackson 1993). The decline in water quality alters stream macroinvertebrate communities that provide food for the cod, reducing the quantity and diversity of food (Wager & Jackson 1993; Simpson & Jackson 1996). Native riparian (riverside) vegetation is crucial for Mary River Cod, because they require shaded pools and woody debris (H.S. Midgley, as cited in Rowland 1993). The main surviving populations of cod are in reaches of tributaries surrounded by native forest, or riparian strips of native vegetation adjacent to pine plantations. Cod have declined or disappeared from cleared areas such as the lower reaches of Obi Obi Creek (Simpson 1994; Simpson & Jackson 1996). Desnagging has occurred in parts of the Mary River in the past, which has removed breeding habitat for the Mary River Cod (Simpson & Jackson 2000).

Dams and weirs
Mary River Cod stocked in impoundments have high growth rates and appear to be maturing, but no breeding has been reported (Simpson & Jackson 1996; Wager & Jackson 1993). Simpson (1994) suggested that dams might not have the water flow and temperature regime required to trigger spawning in many native fish, including Mary River Cod. Cod only spawn when the water reaches a certain temperature (20° C). Females reabsorb their eggs and do not spawn if conditions are unsuitable (Todd et al. 2005). Water in dams is generally still, and eggs in still water in captivity are susceptible to fungal disease (Simpson & Jackson 2000).

Loss of native vegetation due to dam construction is likely to be detrimental to the Mary River Cod. Riverside trees provide necessary shade and shelter (Simpson & Jackson 2000), and are often lost when impoundments are constructed, because they do not tolerate root inundation (Tucker et al. 2000).

Releases of cold water from impoundments (particularly Borumba Dam on Yabba Creek, Baroon Pocket Dam on Obi Obi Creek, and Lake Macdonald on Six Mile Creek) are also likely to affect the timing of breeding and to reduce recruitment downstream (Simpson & Jackson 2000). Repeated releases of cold water from dams during summer and autumn can cause local extinction in the closely-related Murray Cod, because eggs and larvae do not survive below 13° C, and there is a drop in survival below 16° C. Low water temperatures also inhibit ovary development (Todd et al. 2005). Dams can also change the water quality and habitat downstream, because they often release poorly oxygenated water, increase sediment and cause bank erosion through flow regime changes (Walker 1985). Simpson (1994) suggested that changed flow and water quality as a result of Borumba Dam may be the reason why Mary River Cod have been unable to survive in or re-establish in Yabba Creek, despite the relatively intact vegetation downstream of the dam. The more recent (1985) impoundment of Obi Obi Creek has increased siltation and changed flows downstream. Low volumes of water are released from Lake Macdonald into Six Mile Creek, and Simpson (1994) found that during 1991, flow in the creek was virtually absent and oxygen levels in the water fell to critically low levels.

Impoundments inhibit the movements of Mary River Cod and prevent fish in different tributaries from interbreeding. Simpson & Mapleston (2002) found that radio-tracked wild cod migrating in river tributaries did not approach dam walls. Populations in tributaries of the Mary River are largely isolated from each other by weirs and barrages (Simpson 1994). Adult cod are periodically highly mobile, sometimes for several months at a time. If these migrations benefit survival and/or breeding, as Simpson & Jackson (2000) suggest, then the numerous impoundments that restrict movements are likely to be detrimental to population health. Newly-independent larvae of Murray Cod disperse by drifting downstream, so impoundments, irrigation channels and other infrastructure on the river interfere with dispersal and can kill or injure larvae through physical damage or stranding (Koehn & Harrington 2005). This is also likely to apply to drifting Mary River Cod larvae. Conditions in impoundments often favour introduced fish over native riverine species, so dams could exacerbate any negative effects of non-native fish on Mary River Cod living in dams (Simpson 1994).

Mary River Cod have been killed by spillage of water treatment wastes (Fisheries Division, Queensland Department of Primary Industries 1994; Simpson & Jackson 2000; Wager & Jackson 1993). Water quality in the vicinity of Gympie is affected by secondarily treated and chlorinated discharge from a sewerage treatment plant, which increases nutrients and decreases oxygen in the water (EPA 2001). Some effluent is also released into the river at Kenilworth during high flows (Pusey et al. 1993). Meatworks effluent, pesticide and herbicide runoff also affect the river bank and water quality in sections of the Mary River (EPA 2001).

Introduced species
Mary River Cod are potentially threatened by fish introduced from outside the Mary River system, including fish native to other parts of Australia. The Golden Perch Macquaria ambiguais an Australian species with very similar habits to the Mary River Cod, so it could compete with the Mary River Cod for food and habitat, reducing its survival (Simpson 1994; Wager & Jackson 1993). Golden Perch were collected at 17% of sites (9 of 52) surveyed by Simpson (1994) in the Mary River system. They have been stocked in Baroon Pocket Dam, upstream of the Mary River Cod habitat in Obi Obi Creek, and in Lake Macdonald, upstream of the Mary River Cod habitat in Six Mile Creek. They are now relatively common in Six Mile Creek, and have recently invaded Obi Obi Gorge. Golden Perch are very uncommon in Tinana-Coondoo Creek (Simpson & Jackson 2000).

Murray Cod Maccullochella peelii may have been introduced to the Mary River several times in the past, but this is unconfirmed (Simpson & Jackson 2000). Rowland (1989) stated that Murray Cod no longer occur in the Mary River. Hybridisation with Murray Cod would be a serious threat to the Mary River Cod (Rowland 1993).

The Mary River Cod could also be out-competed by fish that are native to the Mary River, especially if these fish are increased by artificial stocking and if changed conditions favour other species of fish over the cod. The Australian Bass Macquaria noveamaculata naturally occurs in the lower Mary River, it may prey on juvenile cod, and compete with the cod for food and space. Its numbers have increased following stocking (Simpson 1994; Simpson & Jackson 1996). The Spangled Perch Leipotherapon unicolormay also compete with the Mary River Cod, but it is unclear whether it is native to the Mary River system (Simpson 1994).

Other threats
Because it now occurs in small, isolated populations, other potential threats to the Mary River Cod include disease, the loss of genetic variability, and inbreeding. The intrinsic biology of this species has probably prevented its recovery from the low population levels caused by habitat alteration and overfishing (Rowland 1993).

Simpson & Jackson recommended further radio-tracking studies to determine the movements of the Mary River Cod in different streams (Simpson & Jackson 2000) as well as research into the habitat requirements of juvenile Mary River Cod (Simpson & Mapleston 2002).

Simpson & Jackson (2000) recommended that no new non-indigenous fish should be introduced into the Mary River drainage, including farm dams. In particular, Murray Cod and eastern freshwater cod should not be introduced. Non-native fish already present in the Mary River include the Silver Perch Bidyanus bidyanus, Saratoga Scleropages leichhardtii, the introduced Guppy Poecilia reticulata, Swordtail Xiphophorus helleri, and Mosquito Fish Gambusia holbrooki. Their effects on the Mary River Cod and its habitat are unknown and may warrant further investigation, particularly the mosquitofish, which has caused declines in native fish elsewhere (Pusey et al. 1993; Simpson & Jackson 1996).

In 1994 Simpson suggested that timed releases of water from Lake Macdonald into Six Mile Creek may be required to maintain water quality. Simpson & Jackson (2000) recommended that new water storages should not be constructed until their effects on cod have been assessed, and barriers to fish migration in south east Queensland should be documented, assessed, and fitted with appropriate fishways. Fishways were recommended for all stream barriers within the range of the Mary River Cod, as were stream crossings designed according to QDPI guidelines to minimize their impact on fish (Simpson & Mapleston 2002). Vertical slot fishway designs that are suitable for Murray Cod are likely to be used by Mary River Cod, but research is needed to confirm this. Baumgartner et al. (2006) found that weirs in which water falls over the top of the wall down a spillway are relatively safe for juvenile Murray River Cod, but other types of weirs ('undershot weirs' or 'sluice weirs') which draw larvae through turbulent water, cause severe mortality of larval Murray Cod and Golden perch. This probably also applies to juvenile Mary River Cod.

Simpson & Mapleston (2002) stated that in order to protect the Mary River Cod, large woody debris in the Mary River and its tributaries should be preserved and enhanced, snags should not be removed, stream channelisation should be avoided, and streamside vegetation should be protected and re-established where it has been cleared. For example, stock should be excluded from revegetation plots using flood-proof fencing, and riparian seed-source trees need to be maintained (Simpson & Jackson 2000).

There has been a captive breeding program for Mary River Cod since 1983. One hatchery has a licence to produce larvae. Lake Macdonald hatchery staff have developed captive breeding techniques using a combination of outdoor earthen ponds and indoor rearing tanks. Broodstock are collected from the wild and from stocked dams each year from a wide a geographic range as possible, replacing the previous year's broodstock. Fish collected from stocked dams are kept separate from those collected from the river tributaries. The 40 to 50 cod establish territories and are paired in the ponds. They spawn in pipes fitted with removable liners. The liners and eggs adhering to them are removed to indoor troughs of running water to hatch, to avoid fungal disease. Fingerlings were formerly released only into stocked dams at 50 mm long, around ten weeks old. Since 1998, there has been a program to increase the area of occupancy of wild cod by also stocking the Mary River with fingerlings 30 to 40 mm long. Using small larvae, there is more opportunity for natural selection on fry in the river, rather than adaptation to hatchery conditions. In the Mary River, fingerlings are released into uninhabited reaches with suitable habitat (or newly rehabilitated habitat). Each site is stocked for four consecutive years. 39000 fingerlings have been stocked into 42 sites in the Mary River and its tributaries since 1998 (Simpson & Jackson 2000). Progeny of broodstock from impoundments are released into impoundments outside the Mary River catchment. Between 1983 and 1998 over 67000 fingerlings were released into impoundments in the Mary, Brisbane, Nerang, Albert-Logan, and North Pine River catchments (Wager & Jackson 1993; Simpson & Jackson 1996).

Removal of cod from the Mary River catchment by the public has been prohibited since 1998. Any Mary River Cod caught when fishing must be immediately released. Simpson (1998) recommends using barbless hooks, handling cod with a wet cloth or wet hands, holding cod horizontally while supporting the body underneath rather than vertically (which can damage internal organs), and allowing the cod to swim away by holding it gently in the water. Recreational anglers are permitted to catch and keep one individual per day of 50 cm minimum total length outside of the Mary River system, where Mary River Cod have been stocked.

Golden Perch and Silver Perch are no longer stocked in the Mary River basin (Wager 1994; Simpson 1994).

The Mary River Cod Research and Recovery Plan

provides a guide to threat abatement and research strategies for the Mary River Cod (Simpson & Jackson 2000).

The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.

Threat Class Threatening Species References
Agriculture and Aquaculture:Agriculture and Aquaculture:Land clearing, habitat fragmentation and/or habitat degradation The Mary River Cod Research and Recovery Plan - 1996-2001 (Simpson, R. & Jackson, P., 1996) [Recovery Plan].
Agriculture and Aquaculture:Livestock Farming and Grazing:Grazing pressures and associated habitat changes Border Ranges Rainforest Biodiversity Management Plan - NSW & Queensland (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010n) [State Recovery Plan].
The Mary River Cod Research and Recovery Plan - 1996-2001 (Simpson, R. & Jackson, P., 1996) [Recovery Plan].
Biological Resource Use:Fishing and Harvesting Aquatic Resources:Habitat modification and negative impacts on species numbers due to recreational fishing The Mary River Cod Research and Recovery Plan - 1996-2001 (Simpson, R. & Jackson, P., 1996) [Recovery Plan].
Climate Change and Severe Weather:Climate Change and Severe Weather:Climate change altering atmosphere/hydrosphere temperatures, rainfall patterns and/or frequency of severe weather events Border Ranges Rainforest Biodiversity Management Plan - NSW & Queensland (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010n) [State Recovery Plan].
Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat loss, modification and/or degradation Border Ranges Rainforest Biodiversity Management Plan - NSW & Queensland (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010n) [State Recovery Plan].
Ecosystem/Community Stresses:Indirect Ecosystem Effects:Loss and/or fragmentation of habitat and/or subpopulations Border Ranges Rainforest Biodiversity Management Plan - NSW & Queensland (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010n) [State Recovery Plan].
Energy Production and Mining:Mining and Quarrying:Habitat modification through open cut mining/quarrying activities The Action Plan For Australian Freshwater Fishes (Wager, R. & P. Jackson, 1993) [Cwlth Action Plan].
Human Intrusions and Disturbance:Human Intrusions and Disturbance:Human induced disturbance due to unspecified activities Border Ranges Rainforest Biodiversity Management Plan - NSW & Queensland (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010n) [State Recovery Plan].
Human Intrusions and Disturbance:Recreational Activities:Disturbance, especially from human recreational activities and development The Mary River Cod Research and Recovery Plan - 1996-2001 (Simpson, R. & Jackson, P., 1996) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation Cabomba caroliniana (Cabomba, Fanwort, Carolina Watershield, Fish Grass, Washington Grass, Watershield, Carolina Fanwort, Common Cabomba) Weeds of National Significance Cabomba (Cabomba caroliniana) Strategic Plan (Agriculture & Resources Management Council of Australia & New Zealand, Australian & New Zealand Environment & Conservation Council and Forestry Ministers, 2000c) [Threat Abatement Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation by weeds Border Ranges Rainforest Biodiversity Management Plan - NSW & Queensland (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010n) [State Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition, predation and/or habitat degradation by fish The Mary River Cod Research and Recovery Plan - 1996-2001 (Simpson, R. & Jackson, P., 1996) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive and Other Problematic Species and Genes:Predation, competition, habitat degradation and/or spread of pathogens by introduced species Border Ranges Rainforest Biodiversity Management Plan - NSW & Queensland (NSW Department of Environment, Climate Change and Water (NSW DECCW), 2010n) [State Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive and Other Problematic Species and Genes:Presence of pathogens and resulting disease Maccullochella ikei an endangered species of freshwater cod (Pisces: Percichthydae) from the Clarence River System, NSW and Maccullochella peelii mariensis, a new subspecies from the Mary River system, Qld. Records of the Australian Museum. 45:121-125. (Rowland, S.J., 1993) [Journal].
Invasive and Other Problematic Species and Genes:Problematic Native Species:Competition, grazing, predation and/or habitat degradation by rats The Mary River Cod Research and Recovery Plan - 1996-2001 (Simpson, R. & Jackson, P., 1996) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Problematic Native Species:Psittacine Circoviral Disease The Action Plan For Australian Freshwater Fishes (Wager, R. & P. Jackson, 1993) [Cwlth Action Plan].
Natural System Modifications:Dams and Water Management/Use:Changes to hydrology including construction of dams/barriers The Mary River Cod Research and Recovery Plan - 1996-2001 (Simpson, R. & Jackson, P., 1996) [Recovery Plan].
Natural System Modifications:Other Ecosystem Modifications:Reduced habitat shading The Mary River Cod Research and Recovery Plan - 1996-2001 (Simpson, R. & Jackson, P., 1996) [Recovery Plan].
Natural System Modifications:Other Ecosystem Modifications:Removal of wood snags from waterways The Mary River Cod Research and Recovery Plan - 1996-2001 (Simpson, R. & Jackson, P., 1996) [Recovery Plan].
Pollution:Pollution:Changes to water and sediment flows leading to erosion, siltation and pollution The Mary River Cod Research and Recovery Plan - 1996-2001 (Simpson, R. & Jackson, P., 1996) [Recovery Plan].

Arthrington, A.H. & B.J. Pusey (2003). Flow restoration and protection in Australian rivers. Australian rivers. River Research and Applications. 19:377-395.

Australian Fish Collection Records (undated). Collation of records from Australian Fish Collections.

Baumgartner, L.J., N. Reynoldson & D.M. Gilligan (2006). Mortality of larval Murray cod (Maccullochella peelii peelii) and golden perch (Macquaria ambigua) associated with passage through two types of low-head weirs. Marine and Freshwater Research. 57:187-191.

Cann, J. & J. Legler (1994). The Mary River Tortoise: a new genus and species of short-necked chelid from Queensland, Australia. Chelonian Conservation and Biology. 1 (2):81-96.

Cogger, H.G., E.E. Cameron, R.A. Sadlier & P. Eggler (1993). The Action Plan for Australian Reptiles. [Online]. Canberra, ACT: Australian Nature Conservation Agency. Available from:

Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC) (2011i). Survey guidelines for Australia's threatened fish. EPBC Act survey guidelines 6.4 . [Online]. EPBC Act policy statement. Canberra, ACT: DSEWPAC. Available from:

Environmental Protection Agency, Queensland (2001). Mary River- water quality condition and trends. Queensland Waterways 6: December 2001.

Flakus, S. (2002). Ecology of the Mary River Turtle, Elusor macrurus. M.Sc. Thesis. University of Queensland.

Harris, J.H. & S.J. Rowland (1996). Family Percichthyidae - Australian freshwater cods and basses. In: McDowall, R.M., ed. Freshwater Fishes of South-eastern Australia. Rev. ed:150-163. Chatswood, Sydney: Reed Books.

Humphries, P. (2005). Spawning time and early life history of Murray cod, Maccullochella peelii peelii (Mitchell) in an Australian river. Environmental Biology of Fishes. 72:393-407.

King, A.J. (2004). Ontogenetic patterns of habitat use by fishes within the main channel of an Australian floodplain river. Journal of Fish Biology. 65:1582-1603.

Koehn, J.D. & D.J. Harrington (2005). Collection and distribution of the early life stages of the Murray cod (Maccullochella peelii peelii) in a regulated river. Australian Journal of Zoology. 53:137-144.

Koehn, J.D. & D.J. Harrington (2006). Environmental conditions and timing for the spawning of Murray cod (Maccullochella peelii peelii) and the endangered trout cod (M. macquariensis) in southeastern Australian rivers. River Research and Applications. 22:327-342.

McDowall, R.M. ed (1996). Freshwater Fishes of South-Eastern Australia rev. edn. Chatswood, NSW: Reed Books.

Merrick, J.R. & G.E. Schmida (1984). Australian Freshwater Fishes - Biology and Management. Netley, South Australia: Griffin Press.

Pusey, B.J, A.H. Arthington & M.G. Read (1993). Spatial and temporal variation in fish assemblage structure in the Mary River, south-eastern Queensland: the influence of habitat structure. Environmental Biology of Fishes. 37(4):355-381.

Pusey, B.J., M.J. Kennard & A.H. Arthrington (2000). Discharge variability and the development of predictive models relating stream fish assemblage structure to habitat in northeastern Australia. Ecology of Freshwater Fish. 9:30-50.

Rowland, S.J. (1985). Aspects of the biology and artificial breeding of the Murray cod, Maccullochella peelii and the Eastern Freshwater Cod, M. ikei sp. nov. Ph.D. Thesis. Macquarie University, Ryde, NSW.

Simpson, R. (1994). An investigation into the habitat preferences and population status of the endangered Mary River Cod (Maccullochella peelii mariensis) in the Mary River System, south-eastern Queensland. Dept Primary Industries, Brisbane.

Simpson, R. & Jackson, P. (1996). The Mary River Cod Research and Recovery Plan - 1996-2001. [Online]. QLD DPI. Available from:

Simpson, R.R. & A.J. Mapleston (2002). Movements and habitat use by the endangered Australian freshwater Mary River Cod Maccullochella peelii mariensis. Environmental Biology of Fishes. 65:401-410.

Todd, C.R., T. Ryan, S.J. Nicol & A.R. Bearlin (2005). The impact of cold water releases on the critical period of post-spawning survival and its implications for Murray cod, Maccullochella peelii peelii: A case study of the Mitta Mitta River, in south-eastern Australia. River Research and Applications. 21:1035-1052.

Tucker, A.D., T. Priest, E. Guarino & P. Couper (2000). Turtle biodiversity in regard to regional conservation planning: additional recommendations for mitigation in Cumulative Effects of Dams and Weirs on Freshwater Turtles: Fitzroy, Kolan, Burnett and Mary Catchments. Report for Queensland Parks & Wildlife Service, Bundaberg. Page(s) 105-130.

Wager, R. (1994a). Fish translocation and biodiversity of Queensland freshwater fishes. Australian Biologist. 7, No. 1:23-32.

Wager, R. & P. Jackson (1993). The Action Plan For Australian Freshwater Fishes. Canberra, ACT: Australian Nature Conservation Agency.

Walker, K.F. (1985). A review of the ecological effects of river regulation in Australia. Hydrobiologia. 125:111-129.

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This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.

Citation: Department of the Environment (2014). Maccullochella mariensis in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: Accessed Wed, 17 Sep 2014 23:44:34 +1000.