Daughterless fish technology

Project Leader: Dr Ron Thresher, CSIRO Marine

Aim: To conduct laboratory development and trials of daughterless technology for the control of invasive fish species.

Projects: 4.f.3

Project summary

Development of ‘daughterless’ technology, that is, an inherited genetic construct that biases offspring sex ratios towards males, offers hope as the first long-term sustainable management tool for the control and possible eradication of alien fish species in the M-D Basin. Detailed modelling and the initial development of a suitable construct was started by CSIRO Marine and Atmospheric Research and continued under the auspices of the Pest Animal Control CRC. Encouraging results (including viable daughterless fish swimming in the lab) were achieved, warranting the continuation of daughterless development in the IA CRC.

The global objective of the project remains to develop a practical option for controlling, if not eradicating, carp from the Murray-Darling Basin using as a core technology a genetic construct that biases population sex ratios and drives population fertility to zero.

The IA CRC daughterless project has successfully tested two variants of a prototype sex-determining construct in a model species (medaka) and is now in the process of determining whether the construct can be integrated into the species genome to make the sex-distortion an inherited feature.

A prototype carp daughterless construct was built, wholly of native carp genetic material.

Preliminary trials were undertaken on options for sterilising or killing females as complementary options for sex ratio distortion.

Options for including an ‘off-switch’ in the construct, as an ultimate safety feature for the technology were assessed. Advice from stakeholders indicated that this not a useful feature for the technology.

The continuing project will:

  • commence trials of the genetic technology in carp. This will be done through an already established collaboration with fisheries geneticists at Auburn University (USA), which has accredited facilities for and experience with genetic transformation of carp. The existing daughterless carp prototype (DC-1) will be tested for effects on sex determination, along with complementary genetic constructs that hypothetically also distort operational sex ratio. If results of the trials are positive, first steps will be taken to develop an integrated carp lineage
  • continue and complete testing the effect of the technology on laboratory fish populations. This will be done by assessing the long-term patterns of inheritance and effectiveness of sex-determining constructs at altering sex in a model fish species, by refining and optimising the technology in the light of recent developments in genetic technology to improve its efficacy and gene targeting, and by stocking fish carrying sex-ratio altering constructs into model species populations in the laboratory to quantify effects on population viability. This work will be supported by two IA CRC PhD projects that are investigating the physiological and genetic basis of sex determination and RNA interference (the key gene blocking technology being used in this study) in fish
  • undertake a risk assessment and synthesis of the technology for input into a national carp control plan. This material will be summarised in a project final report that will also include a recommended program and cost estimates for field testing and implementation of the technology.

Key achievements

  • Successfully tested of two variants of a prototype sex-determining construct in a test species, medaka.
  • A prototype carp daughterless construct has also been built, wholly of native carp genetic material.
  • Preliminary trials were undertaken on options for sterilising or killing females as complementary options for sex ratio distortion.
  • The agreement for extension of the project was negotiated in 2008-09 and saw the commencement of trials of the genetic technology in carp in collaboration with fisheries geneticists at Auburn University (USA) and the continued testing of the effect of the technology on laboratory fish populations – supported by two IA CRC PhD projects that are investigating the physiological and genetic basis of sex determination and RNA interference (the key gene blocking technology being used in this study) in fish.
  • One of the associated PhD students, Megan Barney submitted her thesis in August 2009, and will continue working on this project as a CSIRO employee.

Key deliverables

  • Complete screening of model species lineages for construct integration and effectiveness.
  • Start tests of effectiveness and fitness effects of constructs in carp.
  • Determination of effectiveness of constructs on population viability and production of data for model revisions.
  • Improve efficacy of genetic technology by incorporating latest developments of genetic technology into construct design.

Project team

Peter Grewe, Jodie van de Kamp, Nic Bax, Jawahar Patil, Rob Gurney, Keith Hayes, Rasanthi Gunasekera, Giles Campbell, Miles Canning, Tim Fountain, Janina Beyer, Peter Koopman, Dagmar Wilhelm, Keith Bell, Anne Kapuchinski (University of Minnesota), Michael Jones (Michigan State University), Megan Barney, Lindsey McFarlane.

Project partners

IA CRC, Murray-Darling Basin Authority, CSIRO Marine, University of Queensland, K&C Fisheries, University of Minnesota, Michigan State University, University of Tasmania, Auburn University Alabama.

Further information

Patil JG and Gunasekera RM (2008) Tissue and sexually dimorphic expression of ovarian and brain aromatase mRNA in the Japanese medaka (Oryzias latipes): implications for their preferential roles in ovarian and neural differentiation and development. General and Comparative Endocrinology 158: 131-137.

Patil JG and Hinze S (2008) Simplex PCR assay for positive genetic sex determination in both sexes of the medaka (Oryzias latipes). Marine Biotechnology 10(6): 641-644.

Thresher RE (2008) Autocidal technology for the control of invasive fish. Fisheries 33: 114-121.

Thresher RE (2007) Genetic options for the control of invasive vertebrate pests: prospects and constraints pp 318-331. In: Witmer GW, Pitt WC and Fagerstone K (eds) Managing Vertebrate Invasive Species: Proceedings of an International Symposium. USDA APHIS Wildlife Services, Fort Collins, Co

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