Robert Simpson and Peter Jackson
Queensland Department of Primary Industries, Fisheries Group
- 1. Introduction
- 2. Review of available information
- 3. Research and recovery plan
- Bibliography of publications containing information on Mary River Cod
- Appendix 1. Costing of budgets
- Appendix 2. The Mary River Cod breeding and restocking program
The preparation of this publication was funded by the Endangered Species Program of Environment Australia. The views expressed are those of the authors and the Mary River Cod Recovery Team and do not necessarily reflect those of the Commonwealth or Queensland State Government.
Apart from fair dealing for the purposes of private study, research, criticism or review as permitted under the Copyright Act, no part of this publication may be reproduced by any means without the permission of Environment Australia.
Current species status
Endangered (Jackson 1993; Wager & Jackson 1993).
The Mary River cod (Maccullochella peelii mariensis) is one of Australia's most endangered fish. Natural populations of the species are now restricted to suitable areas of habitat in the Mary River system. Freshwater cod (possibly M. p. mariensis) were also present in the Brisbane-Stanley, Albert-Logan and Coomera Rivers at the time of European settlement. Cod are now considered very rare or extinct in these systems. It is estimated that Mary River cod now occur in less than 30% of their former known range in the Mary River system. Remnant populations may have become isolated from each other due to habitat fragmentation and the impoundment of streams.
Habitats and limiting factors
The Mary River cod prefers shaded pool habitats with abundant instream cover (ie. logs, log jams, rock ledges, boulders, undercut banks). The species occurs from high gradient upland streams to slow flowing lower catchment reaches. Submerged logs are thought to be used as nest sites. Individual cod may move long distances during periods of high water flow. Movements tend to be upstream in summer and downstream in autumn. Between periods of movement, cod occupy a restricted home range which they maintain for up to several years. Homing to a former home range following extensive movements has been recorded.
Activities which reduce suitable habitat and limit fish movements are a threat to the Mary River cod. Extensive land clearing in many parts of the Mary catchment has exacerbated erosion and subsequent in-filling of pools. The removal of native riparian vegetation has also led to reduced shading of watercourses, and reduced timber deadfall to provide instream cover. The net effect of these factors has been to reduce and fragment cod habitats. Other factors thought to have contributed to the decline and which limit the natural recovery of cod populations include overfishing and the impoundment and regulation of streams.
Recovery plan objectives
To secure and enhance populations of Mary River cod in the Mary River system, and to restore populations of cod in their historic range in south-eastern Queensland.
- Self-sustaining populations established outside the present range by 2010.
- Conservation status of cod downlisted from 'endangered' to 'vulnerable' by 2010.
- Distribution of cod in the Mary River system increased to encompass at least 60% of their former known range by 2010.
The Mary River Cod Recovery Team was established in 1994 and produced a draft Recovery Plan in 1996. Many of the recommendations of the draft Recovery Plan have already been implemented, and significant progress has been made towards meeting many of the short term objectives. The full list of actions from the draft Recovery Plan is presented here, and progress already achieved is noted. Ongoing management to maintain populations of the Mary River cod will still be required after Recovery Plan objectives are met.
Recommended recovery actions (and progress already achieved) are as follows:
- Establish a program of community involvement and education.
- 1.1. Seek public participation in developing a Recovery Plan by holding a public forums. (completed)
- 1.2. Appoint a part-time officer to develop and coordinate community involvement and education.(officer appointed)
- Review and develop regulations and administrative procedures to ensure protection of the Mary River cod and it's habitats.
- 2.1. Develop a management plan for the cod under the appropriate legislation. (cod protected under Fisheries Act)
- 2.2. Develop a translocation strategy to minimise impacts of non-endemic fish introductions. (DPI Translocation Policy)
- 2.3. Ensure maintenance of fish passage past weirs/dams etc. in south-eastern Queensland streams. (ongoing negotiations)
- 2.4. Develop and implement environmental flow guidelines. (ongoing negotiations)
- 2.5. Seek co-operation of Resource Managers in protecting the cod and it's habitats. (ongoing negotiations)
- 2.6. Coordinate recovery actions/research on the cod with existing studies being carried out by other groups. (ongoing)
- Develop a plan to improve hatchery production of the Mary River cod, and restock throughout the former range.
- 3.1. Develop and implement a management plan for hatchery production of cod. (Five-Year Strategy implemented)
- 3.2. Develop and implement restocking criteria for cod. (Implemented)
- 3.3. Develop and implement restocking/monitoring program for cod. (Implemented)
- 3.4. Develop and implement program to establish breeding populations of cod in impoundments.
- Undertake research on key aspects of Mary River cod ecology and captive-breeding techniques.
- 4.1. Investigate movements and habitat requirements of the cod via a radio-tracking study. (Underway)
- 4.2. Undertake research to improve captive-breeding success, and investigate artificial enhancement of breeding in impoundments. (Underway)
- Restore degraded Mary River cod habitats.
- 5.1. Develop a strategic plan for restoration of cod habitats. (Officer appointed and plan completed)
- 5.2. Implement pilot habitat rehabilitation programs in key areas of the Mary River.(Pilot programs underway)
- 5.3. Implement large-scale rehabilitation program for riparian habitats in south-eastern Queensland streams.
- 5.4. Implement rehabilitation program for instream habitats as per Action 5.1.
- Develop and implement long-term monitoring program for the Mary River cod.
- 6.1. Develop monitoring program in consultation with experts
- 6.2. Implement monitoring program in Mary River and other restocking sites.
|Action||Action 2||Action 3||Action 4||Action 5||Action 6||Total|
* It is anticipated that many of the recovery actions will take significantly longer to undertake than the five year term indicated in the above table. Implementation of the Recovery Plan commenced in 1996, and it is planned to fully review actions and costing after five years (ie. 2001)
Mary River cod occupy a high trophic level in the Mary River system. It is therefore likely that they exert a controlling influence over the population size of prey species (particularly decapod crustaceans and other fish species). Restoration of stream habitats to increase their suitability for cod habitation will lead to increased habitat diversity which will benefit other native aquatic and riverine species, including the little known Mary River turtle.
The Mary River Cod, Maccullochella peelii mariensis (Rowland) (Percichthyidae) is an endangered freshwater fish that occurs only in the Mary River system in southeast Queensland. Despite high public interest in the species throughout the 1900s for its eating and sporting qualities, the cod has only recently been recognised as unique to the Mary River system. Prior to the 1980s, the strong morphological similarities between the Mary River cod, the eastern freshwater cod Maccullochella ikei (Rowland), and the Murray cod Maccullochella peelii peelii (Mitchell) led to the presumption that they were a single species. The taxonomic distinctiveness of the Mary River cod was formally described in 1993 (Rowland 1993).
Freshwater cod also occurred in other coastal rivers in south-east Queensland at the time of European settlement, but their specific taxonomy is not known (Rowland 1985; Wager and Jackson 1993). They have become very rare, and possibly extinct, in the Brisbane-Stanley, Albert-Logan, and Coomera River systems (Figure 1) (Wager and Jackson 1993). Within the Mary River system, the range and abundance of the Mary River cod has also declined and populations are now largely restricted to a few tributaries where relatively undegraded stream habitats remain (Rowland 1985; Simpson 1994). The Mary River cod is listed as endangered by the Australian Society for Fish Biology (Jackson 1993) and in The Action Plan for Australian Freshwater Fishes (Wager and Jackson 1993). Habitat changes and overfishing are considered responsible for the decline of the Mary River cod (Simpson 1994).
Recognition of the precarious status of the Mary River cod led to formation of the Mary River Cod Recovery Team in 1994. The Recovery Team produced the first draft of this Recovery Plan in 1996 and has been working towards its implementation since that time. Significant progress has already been made as outlined in later sections, but much remains to be done to ensure the long-term survival of the cod. The main factor that will determine the ultimate success or otherwise of the cod recovery program is the level of support and involvement received from local communities. Much of the control over how land and water resources are managed, and to what extent overfishing is allowed to continue, lies with the people of the Mary valley. There is a strong desire among local residents to see cod populations restored, as the species is widely recognised as an important part of the culture and history of the region. The challenge, then, is to ensure that the community feels they 'own' the recovery process, and become involved in specific actions, or adopt specific procedures that clearly benefit the cod.
This Recovery Plan has been developed with considerable input from the community. Information on past and present distributions, habits, and spawning biology of the cod has been provided by a variety of people with an interest and knowledge of the species. Public input into the recommended recovery actions was received via a public forum held in Gympie, and in written and verbal responses to a draft of the plan sent to local groups and individuals.
The major components of the Recovery Plan are:
- a review of available information on the species
- a statement of the objectives of the Recovery Plan, and the criteria by which recovery of the species will be measured
- a list of the actions required to assist recovery of the species
- a schedule detailing the implementation and costing of recovery actions