New vaccine hope for rainbow trout fry

A NEW vaccine for rainbow trout is to be trialled in a project led by Dawnfresh, Scotland’s biggest trout farmer, and the University of Stirling’s Institute of Aquaculture (IoA).

A consortium, which also includes Kames Fish Farming, another Scottish trout farm operator, and Tethys Aquaculture, an aquaculture research impact company, will test the rainbow trout fry syndrome (RTFS) vaccine during field trials in a bid to gain a licence for its use.

Supported by the Scottish Aquaculture Innovation Centre (SAIC), the programme aims to improve fish welfare and unlock the sector’s potential.

The vaccine was developed by the IoA as part of a five-year European Commission funded project called Targetfish, in which Tethys Aquaculture acted as the project’s industry forum leader.

RTFS is a common disease in trout and has been responsible for the substantial loss of stocks, with some sites reporting high average early stage mortality rates.

However, the diversity of the bacteria that cause RTFS has made vaccine development challenging, while the very small size at which fish tend to be affected renders injections unsuitable.

Although antibiosis is a treatment option, the industry’s drive to minimise antibiotic usage, reduce losses, and improve welfare required a new approach.

In response, the IoA team developed a dip vaccine for trout which can be administered to fry in a very low stress and low risk manner.

It is hoped that the vaccine, combined with best farm management practices, will protect fish until they are large enough to fend off infection themselves.

Dr Rowena Hoare, from the IoA, said: ‘RTFS has been a major problem for the rainbow trout industry for decades.

‘We are delighted that this project has been funded by SAIC, enabling our novel RTFS vaccine to be tested on two fish farm sites.

‘We hope in the future to combine this with other vaccines to assist in the sustainability of the trout industry.’

Richard Hopewell, fish health manager at Dawnfresh, added: ‘We are constantly striving to improve sustainability, health and welfare within the trout farming sector.

‘We believe this vaccine could bring great benefits in these areas, as well as the potential to reduce antibiotic usage even further to some of the lowest levels for all food producing animals.’

Polly Douglas, aquaculture innovation manager at SAIC, said: ‘This vaccine could be a major step forward for trout wellbeing – field trials are another significant milestone on the way to a vaccine that can be used across the industry.

‘Trout farming has long been hindered by the pervasiveness of RTFS, which can have a serious impact on fish.

‘If successful, this vaccine could provide a sustainable foundation for growing trout farming in the UK, unlocking additional capacity for the sector and potentially leading to a significant reduction in cost.

‘It’s another example of how industry and academia can work together to solve some of the biggest problems faced by aquaculture.’