The Welfare Needs of the Nile Tilapia (the Second Most Commonly Farmed Freshwater Fish in the World)
Institute of Aquaculture, University of Stirling
Despite being the second most commonly farmed freshwater fish globally, the welfare needs of the Nile tilapia (Oreochromis niloticus) are poorly understood1. This is primarily driven by having received far less research attention than ‘high value species such as the Atlantic salmon (Salmo salar) or the rainbow trout (Oncorhynchusmykiss). However, the sheer number of animals involved in such operations that are neither reared nor slaughtered humanely make it a highly neglected, tractable and scalable issue. As it stands, most operational welfare indicators (OWIs) used to assess the welfare status of tilapia in farm settings have been adapted from other species and simply assumed to be valid but as my preliminary research has proven, this is not the case.
My work has shown that, as with the lumpfish (Cyclopterus lumpus)2, even standard morphometric growth or nutritional indicators such as the body condition factor—often used in assessing the welfare status of farmed salmon—are appropriate for the Nile tilapia given its allometric growth pattern and non-elongated body shape. My current research is aimed at developing, validating and refining unique OWIs for Nile tilapia. The idea is then to take these indicators and use them to: (1) validate the welfare assessment protocols developed by researchers in the UK andBrazil; and (2) build the foundation for the first true welfare standard for Nile tilapia which can then be adopted by major certifiers such as the Aquaculture Stewardship Council and the Global Seafood Alliance (who operate the Best Aquaculture Practices label) who currently use generic guidelines that hardly guarantee a reasonable level of welfare for the animals in question. In the absence of true welfare parameters, the industry relies on production parameters which are nowhere near sufficient for optimum animal welfare. My work also seeks to answer questions around whether welfare parameters match up with production parameters and quality (i.e., do we have enough scientific basis to make the argument that tilapia reared in higher welfare conditions are higher quality ‘end products’ that can fetch higher prices?).
The subsequent phase of my research will involve visiting a set number of tilapia farms in Egypt, Brazil, Uganda and Thailand (all parts of highly neglected regions and areas where production systems and strains of tilapia differ substantially)to test the validity and robustness of the OWIs I have been developing. This will include an adapted version of body condition factor, fin erosion ratio, hepatosomatic index and a number of other previously unassessed factors such as water turbidity as it relates to stocking density and number of nests versus male: female sex ratio. By validating these specific OWIs for tilapia, we can provide quick and easy ways for farmers to monitor the welfare status of their fish which will help them understand that even if their fish “look OK”, they might be experiencing various states of low welfare.
I will also look at using some of the data collected from ponds and cage production systems to make a high-level comparison of welfare between the two systems. In the face of water quality issues, there is a worrying trend of moving from farming tilapia in ponds to farming them in cages despite the fact that initial(unpublished) research suggests potentially lower welfare in such systems. Amongst other reasons, this is because cages likely do not meet one of the Nile tilapia’s most basic needs— provision of substrate for nesting, burrowing and fulfilling territorial behaviour
- Pedrazzani, A. S., Quintiliano, M. H., Bolfe, F., Sans, E. C. O., Molento, C. F. M. 2020. Tilapia on-farm welfare assessment protocol for semi-intensive production systems. Front Vet Sci, 25;7:606388.DOI: 10.3389/fvets.2020.606388.
- Gutierrez Rabadan, C., Spreadbury, C., Consuegra, S., Garcia de Leaniz, C. 2021. Development, validation and testing of an Operational Welfare Score Index for farmed lumpfish Cyclopterus lumpus L. Aquaculture, 531: 735777.