Flesh colour in Atlantic salmon is considered a fundamental, if not the most important, quality parameter, and affects acceptance and price of the product. The dietary pigments responsible for flesh colour (i.e. astaxanthin and canthaxanthin) are expensive and represent 6-8% of the total production cost. Therefore, reduced flesh colour in the stock results in considerable economic losses. Several factors have been shown to impact flesh colour (e.g. environment, diet formulation, size, genetics) highlighting the complexity underlying the variation. As variable/reduced flesh colour was identified in a portion of the Petuna stock following periods of high summer temperatures, the project focused on the possible genetic effect on the trait. Furthermore, due to a general lack of knowledge of the molecular mechanisms responsible for flesh colour and its metabolism in general, which involves multiple organs and tissues, and given the opportunity to compare good and affected individuals, such investigations were also undertaken. In light of climate change and increasing seawater temperature, understanding the genetic component of the differential response manifested as variable/reduce flesh colour following thermal stress, would pave the way for improving genetic selection and producing fish with increased thermal tolerance. Finally, detection and understanding of the variation affecting flesh colour in Atlantic salmon are fundamental in order to improve marketability of the product.
Final report
This report describes critical findings and new knowledge on flesh colour variation, from both a genetic and a molecular perspective, in Atlantic salmon in Tasmania. The investigation on flesh colour variation, due to its strong correlation with high seawater temperature, led to new important insights into thermal tolerance in Atlantic salmon and their performance in a context of climate change and global warming.
The project was carried out between June 2016 and June 2020 and was the result of a collaboration between the University of the Sunshine Coast (USC) and Petuna Aquaculture (Petuna), initiated by Dr Mark Porter and Prof Abigail Elizur. The principal investigator of the project was Prof. Abigail Elizur (USC) and she was supported by two co-investigator, Dr. Tomer Ventura (USC) and Dr. Gianluca Amoroso (Petuna). Two additional co-investigators from USC, Dr. Chan D.H. Nguyen and Ms Thu T.M. Vo, were included at a later stage in order to carry out part of the research required for the project completion and formed part of their PhD projects. The investigation of the fish took place in northern Tasmania where Petuna owns both freshwater and marine sites and all the laboratory work was undertaken at both USC Genecology Research Centre and at Xelect, a genetic services provider based in Scotland (UK).
This project was originally designed to study an issue which is impacting commercial production in Petuna. Flesh colour variation post-summer (at times extending to harvest), had been identified during 2015-16 by Petuna to affect commercial value. As this issue is not impacting Petuna only, this project was expected to generate important knowledge on the factors which contribute to reduced flesh colour in Atlantic salmon stocks and result in significant ‘spill-over’ of information that will assist the wider Tasmanian salmon industry.
