Recovery of the endangered trout cod Maccullochella macquariensis: What have we achieved in more than 25 years?

Marine and Freshwater Research (Impact Factor: 1.47). 09/2013; 64(9):822–837. DOI: 10.1071/MF12262


Recovery of threatened species is often necessarily a long-term process. The present paper details the progress towards the recovery of trout cod, Maccullochella macquariensis, an iconic, long-lived fish species first listed as threatened in the 1980s. The objectives, actions and progress over three successive national recovery plans (spanning 18 years) are assessed, documenting changes to population distribution and abundance and updating ecological knowledge. Increased knowledge (especially breeding biology and hatchery techniques, movements, habitats and genetics) has greatly influenced recovery actions and the use of a population model was developed to assist with management options and stocking regimes. Key recovery actions include stocking of hatchery-produced fish to establish new populations, regulations on angling (including closures), education (particularly identification from the closely related Murray cod, M. peelii) and habitat rehabilitation (especially re-instatement of structural woody habitats). In particular, the establishment of new populations using hatchery stocking has been a successful action. The importance of a coordinated long-term approach is emphasised and, although there is uncertainty in ongoing resourcing of the recovery program, much has been achieved and there is cautious optimism for the future of this species

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    • "One conservation objective of the latter is to " Investigate the use of re-introductions of freshwater catfish to improve the status of the species, and initiate at least two reintroductions into appropriate sites within Victorian waters " . This approach has been applied to other threatened species (Rinne et al. 1986, Ingram et al. 1990, Rowland 2013), and has been particularly successful for trout cod (Ingram and Thurstan 2008, Lyon et al. 2012, Koehn et al. 2013). "
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    ABSTRACT: Freshwater catfish (Tandanus tandanus) is a popular freshwater angling species in rivers of the Murray-Darling Basin (MDB). In recent decades the species has, however, undergone substantial declines in abundance and distribution. In Victoria, freshwater catfish is listed as threatened under the Flora and Fauna Guarantee Act 1988, occurring in small isolated populations only. In 2011, Native Fish Australia (NFA), (Wimmera) Inc. received funds from the Department of Primary Industries’ Recreational Fishing Grants Program to help restore Victoria’s recreational fishery by captive breeding and re-stocking freshwater catfish. The aim of this study was to observe spawning trials on freshwater catfish to produce juveniles for restocking into Victorian waters. Spawning trials focused on use of Ovaprim® to induce ovulation and spermiation in fish that where hand-stripped, and Ovaplant® (Syndel, Canada) to enhance maturation and ovulation in fish allowed to spawn naturally. Nineteen females and 26 males were used in spawning trials conducted in late October 2013, when water temperatures approached 20oC. Tetrauronema, a new myxozoan parasite of freshwater catfish, was observed in a milt sample from one fish. The implications of the presence of this parasite in freshwater catfish is unknown. Most females (70%) injected with Ovaprim were induced to spawn. Broodstock implanted with Ovaplant and transferred to a 0.15 ha pond containing patches of gravel subsequently spawned naturally within a month of being implanted. Small amounts (0.1-1.0 mL) of milt, which was generally watery in consistency, was stripped from males. There was a slight improvement in both milt consistency and sperm activity 2 days after injection with hormones. Relative fecundity of stripped females was low (920-3,370 eggs/kg). Although fertilisation rates (65-100%) were generally high, hatch rates (0-42%) were low and a high proportion (10-20%) of larvae were deformed. These results suggest that not all oocytes in the ovary were mature and consequently, responded to the hormone treatment, and/or fish were not fully conditioned for spawning. Spawning trials are likely to have occurred at the very beginning of the spawning season and so fish may not have been fully mature, which may affected fecundity, gamete quality, hatch rates and larval quality. Fry were reared to fertilised earthen pond, and on 7th February 2014, 1,900 fingerlings were harvested, 1,400 of these were released into Moodemere Lake (Rutherglen) and 500 into Crusoe Reservoir (Bendigo). Observations made during these trials will be used to guide future R&D to improve captive breeding of freshwater catfish. Recommendations include: • Increase broodstock numbers to increase productivity • Reduce broodstock densities in ponds to optimise growth, conditioning and maturation • Supplement the diet of broodstock with live prey (small yabbies) • Remove the fish infected with Tetrauronema to reduce the risk of spreading the disease to other stock • Check for the presence of this parasite in other broodstock during the next spawning season • Undertake induced spawning later in the season, once water temperatures exceed 21oC and before reach 25oC (i.e. early to mid-November) • Inject females and males to be hand-stripped each with a single doses of Ovaprim at 0.5 ml/kg • Repeat natural spawning trials to obtain further information on production levels for comparison with to induced spawning and hand-stripping methods • Rear fry into a pond by themselves using standard fry rearing methods employed for other native fish species.
    Full-text · Technical Report · Dec 2014
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    • "One method that is often used to increase the abundance of endangered fish species is to implement a captive breeding and re-stocking program (Trushenski et al. 2010, Rowland 2013). This approach has been successfully applied to a number of threatened species, especially as trout cod (Maccullochella macquariensis) (Ingram and Thurstan 2008, Koehn et al. 2013). However, introducing hatchery bred fish into a wild population should be a last resort, when native populations are not successfully recruiting or recolonising an area naturally(George et al. 2009). "
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    ABSTRACT: The freshwater catfish (Tandanus tandanus) is endemic to Australia, and can be found in slow moving or still waters throughout Victoria, New South Wales, South Australia and Queensland. The species was once widespread throughout the Murray-Darling River system, but their range has been altered dramatically since European settlement. Native Fish Australia, (Wimmera) Inc received funds from the Recreational Fishing Grants Program to restore Victoria’s recreational fishery by captive breeding and re-stocking freshwater catfish. To support of this project, this study was undertaken to:  Describe the genetic structure of the freshwater catfish populations in Victoria  Provide guidelines for genetic management of a freshwater catfish captive breeding program. Using DNA from 218 individuals, this study examined levels of genetic diversity, expected heterozygosity, effective population size and genetic structuring of the populations, using both mitochondrial and microsatellite data. Both mitochondrial and microsatellite data suggest that the Mallee, a naturally occurring population, is the most diverse population in Victoria. In contrast, the Avoca and Goulburn populations contained the least amount of diversity. The Loddon and Avoca sites were the only populations to contain no unique alleles. The Wimmera contained the highest effective population size (Ne) and the Loddon the lowest. Four genetic clusters were identified in the Victorian populations, which were Zone 1. Mallee, Wimmera, Little Murray, Gum Lagoon, Safe Lagoon Zone 2. Loddon and Avoca (Amphitheatre Res. and Centenary Res.) Zone 3. Phyland Lagoon and Turners Lagoon Zone 4. Goulburn (Lake Nagambie, Majors Creek and Tahbilk Lagoon). The genetic structuring observed in Victoria may be due to limited gene flow between populations along with influences of translocations. Results from the genetic analyses were used to develop guidelines for the genetic management of freshwater catfish broodstock used for stock-enhancement. The following points were recommended: 1. Avoid mixing fish between the four genetic zones identified in Victoria. 2. Use wild-born fish from Zone 1 and Zone 3 populations as broodstock. 3. Tag all broodstock for identification purposes. 4. Develop artificial spawning methods to improve genetic management of stock. 5. Spawn as many broodstock as possible each year. As a minimum spawn at least 10 fish (5 females and 5 males) each year. 6. Maintain as many broodstock as possible. 7. Spawn an equal number of female and male fish each year. 8. Undertake single-pair (one female and one male) matings only. 9. Mate different individuals each year (do repeat mating crosses that were undertaken in previous years). 10. Replace 10% of broodstock each year with new stock. 11. Maintain detailed and accurate breeding records. 12. Undertake stockings in accordance with the policies and protocols of Fisheries Victoria. 13. Spread the target number of fish to be stocked into each site over 4-5 consecutive years. 14. Mark (tag) all fingerlings before release. Following these recommendations will increase genetic diversity of the stocked fish while minimising loss in genetic diversity or changes in genetic structure of existing wild populations.
    Full-text · Technical Report · Nov 2014

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