Mitigating Microbial Hazards - Eliminating HABs risks in salmon farms

Lead Research Organisation: Robert Gordon University


One of the greatest global challenges facing human-kind is ensuring reliable protein production while addressing climate issues. Considerable effort is being committed to the global protein transition in recognition that many sources of protein contribute to unsustainable agricultural practices, however, protein production from aquaculture can have a lower carbon footprint. Furthermore, the programme of work described here aims to contribute several UN sustainability goals, namely, UNSG 2 "End hunger, achieve food security and improved nutrition and promote sustainable agriculture" and UNSG 12: Life Below Water "Conserve and sustainably use the oceans, seas and marine resources for sustainable development".

Once thought of as a luxury food item, today 1 million salmon meals are consumed in the UK each day with the industry growing from a couple of farms 50 years ago to around 200 now. Salmon is one of the UK's biggest food exports and said to be worth close to £1bn a year to the economy. Scotland is the world's third largest producer of farmed Atlantic salmon, producing >200,000 tonnes in 2020. The sector employs >11,000 jobs with the aspiration to double this by 2030. One of the factors that may hamper this goal is the occurrence of Harmful Algal Blooms (HABs) which can cause mass fish mortalities due to damage to gills, the presence of toxins and also oxygen depletion due to high biomass. This ambitious Project will accelerate the innovation of a protective system to eliminate algae before they can cause injury to salmon and significant financial loss.

Over a number of years we have developed photocatalytic systems which, in the first instance destroyed algal and cyanobacteria toxins with potential applications in drinking water treatment. More recently we have advanced this technology to the elimination of harmful cyanobacteria and algae. Photocatalysis is a treatment that employs a catalyst that is activated by light bringing about the release of powerful hydroxyl radicals. One of the significant benefits of this type of treatment is that it does not require the addition of chemicals and the reactive radicals are very short lived (nano seconds) hence are predicted to have minimum negative impact on non-target species. While we have demonstrated the potential of photocatalysis as a novel treatment strategy for a range of microbes in water, the truly adventurous aspect of this investigation will be to unlock new knowledge of the phototaxis of harmful marine algae using very selective wavelengths. With continuing advancements in LED technologies very precise wavelengths can be obtained (c. 15 nm) throughout the visible light spectrum with readily variable light intensity. We will design a bioassay approach to screen known harmful algae to determine if specific LEDs can be used to lure the harmful algae towards the photocatalytic treatment system which will take the form of a curtain that can be deployed to protect salmon cages.

The development of the protective curtain will be carried out through collaboration with international marine engineering experts OTAQ which will expedite design through to deployment of an engineered system suitable for harsh marine environment while also linking directly to the many test sites they are currently working with on salmon farms. The project team also includes experts from Scottish Association for Marine Sciences (SAMS) who have been working with the industry on early warning systems for HABs around salmon farms. The successful deployment of our proposed photocatalytic curtain requires accurate alerts of potentially hazardous algal bloom events. Working with SAMS from the outset will ensure the two novel technologies come together to protect salmon farms supporting future expansion of this important industry.


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