Is temperature driving sex change in barramundi?

Play Video





1. Project summary (maximum 150 words)

Sustainable aquaculture and fisheries are essential solutions to food security, future nutrition and world health. In Queensland, the barramundi fisheries and aquaculture sector produces close to 4000 tonnes and $40 million in revenue each year. Like many other plant and animal species, barramundi change sex, but we are yet to understand how and why. Lack of control over the sex change process presents the single biggest impediment to barramundi breeding programs and a substantial management challenge for wild-caught fisheries. My PhD research looks at genetic switches that turn 'on' and 'off' male and female sex genes. In barramundi, it is likely that these sex switches are influenced by temperature. My research will help us to determine if temperature can be used as a way to control sex change in barramundi aquaculture, and understand the impact of increasing ocean temperatures on sex ratios so that we can future proof our fisheries.

2. How does your project benefit Queensland? (maximum 500 words)

My project will benefit Queensland through the improvement of barramundi aquaculture and fisheries industries; creating a more sustainable product, increasing economic benefits and generating employment opportunities.


While many agricultural sectors have undertaken long-term selective breeding programs to produce more sustainable and economically viable products (e.g. chickens, cattle, crops), the implementation of similar long-term improvement programs for barramundi has been challenging. Barramundi naturally change sex from male (small) to female (large - up to 50kg), meaning that males do not reliably stay male, and females are expensive to maintain, and may take up to 5 years to become sexually mature. Because of this, the present inability to control sex change in barramundi within aquaculture is the single biggest impediment to the instigation of selective breeding. However, by obtaining increased control over barramundi sex change using temperature, hatcheries will be able to better manage genetically strong breeding pairs and ensure the production high quality offspring with faster growth rates and lower feed consumption. As demonstrated by other successful aquaculture industries, it is imperative to have complete control over reproduction to enable industry growth. It is envisaged that this research and the larger project of which it is a part, will finally take the Queensland barramundi industry to this level of control.


Increased knowledge on the environmental and genetic influences on sex change in barramundi will also allow fisheries to predict how ‘size at sex change’ will change as ocean temperatures increase. Wild barramundi populations support recreational, commercial and indigenous fisheries across the breadth of northern Queensland and Australia at large. The average size at sex change for barramundi varies substantially by region. For example, in Queensland populations from the Gulf of Carpentaria sex change at smaller sizes than those on the East Coast, 82 and 90 cm at sex change, respectively, with some populations further north changing sex as small as 50cm. My research has revealed that sex change in this species can, in part, be attributed to epigenetic ('on top of' the genes) switches on several sex genes, yet the environmental cause of the differences in size at sex change observed in wild populations is unknown. If we find that temperature differences between the Gulf and East Coast are driving the differences in the size at which wild populations of barramundi change sex, it will have a substantial effect on the way we manage our fisheries throughout Queensland under current and future conditions.

The development of more efficient barramundi aquaculture, through the commencement of selective breeding, as well as improvement of future fisheries management will provide Queensland barramundi farmers and fishers with increased ability to compete against imported products from Asia and the US. Furthermore, increasing the profitability of enterprises facilitates industry expansion and increased employment opportunities, injecting additional social and economic value directly into the regional Queensland communities in which the industry is largely based.

3. What STEM promotion/engagement activities do you do/have you done? (maximum 500 words)

Although Townsville is a regional city, our location combined with the James Cook University's presence means that there are plenty of engagement opportunities for scientists, particularly in but not limited to the fields of marine biology and aquaculture. I regularly encourage students to get involved in volunteering opportunities, small research projects and STEM-related community events. Specifically, I give talks at schools to share my research and encourage continuation of science related studies throughout secondary schooling. I encourage high-school graduates to enroll in science at events like university open days, which I have participated in at both the University of Queensland (UQ) and James Cook University (JCU). I have formed collaborations, presented posters and spoken at academic conferences in Europe, the US and here in Australia where I myself have been motivated by the research presentations and lifestyle management strategies of high achieving women in my field. To better my presentation and communication skills, I love to participate in public research communication initiatives and was winner of JCU’s 3MT competition in 2017, as well as Runner-up in the Asia Pacific final held at UQ that same year.

In the Molecular Evolution and Ecology Laboratory (MEEL) at JCU I have been an official mentor to seven students, five of which were young women and I am the student representative on the MEEL committee. This position has allowed me the opportunity to make meaningful contact with all members of the lab. I was employed as a student science ambassador for JCU throughout 2015, enabling me to take small school groups on tours of JCU's Marine and Aquaculture Research Facility. I have tutored a number of subjects at the university, where I love to provide one on one support and encouragement to undergraduate and masters students. I have also shared my research through guest lectures in aquaculture coursework subjects like 'Propagation' and 'Stock Improvement'. I am passionate about encouraging students to try their hand at genetics in an applied setting by taking on small research projects in our laboratory. Finally, I am an education officer, diver and aquarist at the local aquarium and each week I give an underwater lecture to the public on the importance of sustainable fisheries and basic marine animal biology. I love being able to engage with the public in this way, often taking the opportunity to share interesting facts about sex-changing fish. I hope that in doing these activities I am able to communicate widely that scientific research is relevant, accessible and achievable to all.



No discussion yet, be the first one to comment


Hi! I'm Alyssa and I'm interested in how we can use scientific research, specifically genetics, to create solutions to biological and environmental problems. Thank you for supporting my page. I c...

Recent Voters