World Aquaculture 2023

May 29 - June 1, 2023

Darwin, Northern Territory, Australia


Gayan L Gunaratne*, Emma Lofthouse, Emma McCall, Harrison Carmody, and Louise Bruce


BMT Commercial Australia,

Level 4/20 Parkland Rd, Osborne Park, WA 6017, Australia


Aquaculture is a rapidly growing industry that requires the management of multiple environmental impacts and operational risks. Mathematical models can aid decision-making processes by quantifying the dispersion and concentration of various chemicals used in the treatment of pathogens as well as the pathogens themselves. Inert tracers provide a robust representation of fluid dynamics, making them an ideal tool for studying the movement and concentration of chemicals and pathogens. In two separate case studies, the TUFLOW FV 3D hydrodynamic model was used to simulate the fate and transport of bath medicine and viruses and model output compared against Environmental Quality Guidelines (EQGs).

In the first case study, we simulated the dispersion of bath medicine used to treat sea lice in a salmon farm to determine acceptable loads for minimal environmental impact. The model outputs allowed us to assess the concentration against EQGs, aiding in the comprehension of dispersion and concentration around the mixing zone and sensitive habitats (Figure 1). Additionally, we tested different management scenarios and assessed their effectiveness in reducing the dispersion and concentration of bath medicine applications.

In the second case study, we simulated inert tracers in a TUFLOW FV model to predict patterns of dispersion of viruses discharge from a series of wastewater outlets close to proposed aquaculture zones. The model outputs were used to predict the area of dispersion for concentration of the virus against EQGs. These maps were used to undertake a risk assessment for health risk for levels acceptable for shellfish production.

Both case studies demonstrate the potential of mathematical models to facilitate environmental impact assessments and mitigate risks to the health of aquaculture. Mathematical models can also optimise treatment use, such as bath medicine, by predicting dispersion and ensuring appropriate concentration. Ultimately, this improves sustainability, environmental performance, and the health and safety of farmed species. In conclusion, inert tracers can aid decision-making process, and this enables farmers, consultants and regulatory bodies to identify and mitigate environmental risks and optimise treatment use, resulting in a more sustainable and safer aquaculture industry.