SRUC Solves the Challenge of CT Scanning Live Fish

Published Wednesday, 12th June 2013 in Research news

CT Scan live fish

While sheep and pigs are regular visitors to SRUC’s CT scanning unit, staff had to get inventive when they were asked to scan 100 live fish.

The request was made by researchers from the University of Stirling’s Institute of Aquaculture. The team explained that a major problem in breeding fish for improved carcass composition is the lack of simple and reliable methods to predict genetic traits. Usually fish have to be killed and then dissected, which, apart from the obvious downside, is also a laborious and time consuming process and prevents selection of such fish as breeders.

The CT scanner allows the operators to select from hundreds of virtual “slices” through the animal’s body, enabling them to look at internal organs, muscle groups, fat deposits and the skeleton. The technology even allows 3D images of the whole animal to appear on the screen so it can be looked at from every angle.
In this bid to understand more about the physiology of tilapias, the second most farmed fish in the world after carp, the researchers brought the fish to the facility to be scanned for fat, muscle and bone percentages. The results of the CT scanning will tell the research team whether there is the potential to use genetic selection to improve product quality and yield.

Dr David Penman, Senior Lecturer at The Instritute for Aquaculture, said: “CT scanning should allow efficient, non-destructive assessment of carcass composition from live fish. Tilapias have a low fillet yield, so three commercially important species were included in this study to allow comparisons between species as well as within, and to look at the effects of age and sex.”

However, it was not immediately clear to those who run the scanner how they could adapt the equipment for fish. Undaunted, Kirsty McLean, Manager of the service, and SRUC Research Technician John Gordon, designed special stackable polystyrene boxes each with  three slots so multiple fish could be can scanned at one time making the procedure far faster and cheaper than individual scanning.

Kirsty says: “The CT scanning service offers a unique opportunity for researchers and commercial clients to collect accurate information on body tissues and internal structures from live animals and other objects. Data can be used in breeding programs and to monitor changes over time in individual samples eg. soil compaction, muscle shape, growth changes etc. We are always happy to explore new opportunities and discuss possible scanning techniques and options for future work or collaboration.”

David visited the facility with Professor Brendan McAndrew and their postgraduate student Khalfan Al-Rashdi, whose PhD is on tilapia genetics. The research team believe that SRUC’s CT scanning facility could offer them the chance to gain a better understanding of the body conformation traits of different species of tilapia and so open the door for further research into selective breeding.

The static CT scanning service has been operating since 1997 and all procedures follow strict animal welfare guidelines. A mild sedative is added to the water the fish are swimming in before they are placed in the polystyrene trays to be scanned. Images taken by the scanner are captured for future analysis using software designed by Biomathematics and Statistics Scotland (BioSS). The whole operation takes just a few minutes.

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