Investing in healthy fish
Our round-up of what’s new in fish health focuses on new projects aimed at increasing the industry’s knowledge.
The Sustainable Aquaculture Innovation Centre (SAIC) has announced its support for three innovation projects aimed at enhancing finfish health and welfare in response to a changing climate and other emerging challenges.
The projects concerned will address three major biological threats to farmed fish: micro-jellyfish, harmful algal blooms (HABs) and proliferative kidney disease (PKD).
Valued at a combined £1.6m, these projects have secured nearly £600,000 in funding from SAIC along with additional support from businesses and organisations operating within the Scottish aquaculture sector.
Green algae cells
Two of the successful projects are already underway. The first is exploring the development of a holographic imaging system to detect and monitor micro-jellyfish at aquaculture sites. It also aims to implement an automated profiling system for HABs in the water column, providing real-time data for fish health management.
The second project builds on previous SAIC-funded initiatives that established predictive biomarkers for assessing gill health in Atlantic salmon. Its objective is to refine these biomarkers using machine learning and non-invasive sampling methods, while investigating their effectiveness in predicting responses to micro-jellyfish exposure and different diets.
Meanwhile, a third project is set to begin in November, focused on stock management strategies for PKD outbreaks in Scotland. The initiative will monitor environmental conditions and immune responses in fish using advanced techniques, aiming to develop predictive models that enhance health management practices and improve vaccine efficacy in aquaculture.
Focus on fish health and welfare
The latest funding awards build on SAIC’s work to date, which has seen almost £11m of investment turned into sector-critical research with a combined value exceeding £71m. These projects have led to the creation of spin-out companies, new products and services, and innovative approaches to tackling sector-wide challenges.
Earlier this year, SAIC announced that it had secured further funding that will enable the innovation centre to build on its work from over the past decade, following the withdrawal of financial support from the Scottish Funding Council, its main source of funds.
SAIC has now sharpened its focus on promoting positive health and welfare outcomes for farmed fish through applied research and knowledge exchange, particularly in response to emerging environmental challenges.
Sarah Riddle, Director of Innovation and Engagement at SAIC, said: “Over the past 10 years, we have prioritised initiatives aimed at enhancing aquaculture’s environmental impact, fish health, and unlocking economic potential. In this current funding call, our sharper focus aligns us even more closely with the sector’s key priorities, fostering collaboration to tackle critical health, welfare, and survivability challenges in fish farming – and each of these projects aims to tackle these areas. Continued knowledge exchange between the sector and academia will also be vital in maintaining Scotland’s position at the forefront of pioneering advancements across the global aquaculture supply chain.”
Linsey Dickson, Interim Executive Director of Research, Innovation and Business Engagement at the University of Stirling, added: “This funding represents a significant boost to the innovative research being conducted across Scotland’s aquaculture sector. By applying cutting-edge technologies and evidence-based practices, these projects are poised to address some of the sector’s most pressing challenges. Close collaboration between academia and the fish farming community is crucial to ensure that our findings translate into actionable solutions that support the future of sustainable seafood production.”
Freshwater treatments via wellboats could help to combat bacteria
Gill health investigated
Norway has launched an initiative to discover more about the growing problem of complex gill disease in salmon.
FHF, the country’s aquaculture and fisheries fund, has awarded NOK 15m (just over £1m) to look into preventive measures against the condition and to develop new tools to evaluate gill function at the edge of the cage.
The FHF said that the challenges of complex gill disease have increased in recent years both in terms of frequency and geographical spread, but also in terms of complexity in causal relationships.
There are currently few tools available to tackle what FHF described as a complex problem.
FHF said the objective will be achieved through three separate sub-objectives, each of which must be answered in separate projects.
These are to evaluate the effectiveness of methods and strategies used in the industry against complex gill disease; establish and validate new methods that can be used at the cage edge to evaluate the respiratory capacity of the gills; and to test new measures that can reduce the risk of gill disease and the development of severe gill inflammation.
The aim of the call for tenders is to generate knowledge about preventive and mitigating measures against the disease and to develop better tools to assess gill function.
Norwegian Veterinary Institute
Fresh water ‘may be answer to salmon disease’
The bacterium that causes pasteurellosis in farmed salmon does not survive for long in fresh water, new tests have shown.
Experimental work has been carried out by the Norwegian Veterinary Institute in this area which has thrown up some interesting results.
The institute said that the pathogenic bacterium Pasteurella has become more widespread in Norwegian fish farming in recent years and is also developing into a major problem for the industry.
Pasteurellosis has become an extremely serious disease, particularly in south-western Norway, and is now the third most important bacteriological issue for salmon farming, said the institute.
Now, a three-year project led by the Norwegian Veterinary Institute and financed by the Norwegian Food and Agriculture Organization (FHF) is providing more knowledge about the bacterium and how to combat it.
The report states: “Experiments with fresh water were carried out after an epidemiological investigation showed that the probability of an outbreak of pasteurellosis increases significantly after thermal or physical de-lousing with seawater, but not after freshwater-based de-lousing.
Duncan Colquhoun
“In the laboratory experiment, it was investigated how long the bacterium Pasteurella atlanticus survives in water with different salt concentrations. But when exposed to 100% fresh water, the bacterium was inactivated within approximately one hour. “
Senior Researcher and Project Manager at the Veterinary Institute, Duncan Colquhoun, said: “Previous work has also shown that hidden infected fish secrete disease-causing bacteria during stressful handling.
“There is, therefore, reason to look more closely at whether freshwater-based lice removal can reduce the severity and number of disease outbreaks after such treatments.”
Anti-fouling agent sparks concerns
A new environmental toxin has been found in farmed salmon in Norway, but for the moment the authorities are keeping an open mind on what action to take because the amounts are so small.
The substance is the anti-fouling agent tralopyril – also known commercially as ECONEA – which is being used to replace copper in the cages as a non-metal paint.
Bjørn Einar Grøsvik (Photo: IMR)
Bjørn Einar Grøsvik, a researcher with the Norwegian Institute of Marine Research (IMR), said: “The substance was found during laboratory tests and the amounts were only just above what could be measured.”
Nevertheless, he feels the discovery is worrying and should be taken seriously. The IMR is recommending that maximum residue levels (MRLs) need to be set for tralopyril, as they have already been for other agents.
“This is a substance that does not exist in nature in the first place, and there are also no set limit values for how much of it is acceptable in foodstuffs or ingredients used in animal feed,” Grøsvik added.
He compared tralopyril with other agents used by the farming industry, such as various drugs against salmon lice.
Scottish salmon pen
He said: “Such drugs can be found in small quantities in fillets, but limit values have been introduced for these substances where calculations have been made of how much is acceptable in terms of food safety.”
He explained there are large gaps in knowledge about tralopyril today, but in its risk assessment of the substance from 2023, the IMR refers to one study carried out on rats.
This showed that the levels of tralopyril found in salmon were significantly lower than the levels that had been found to have a negative health effect in rats.
Tralopyril can probably have a negative effect on the gills of the salmon, the IMR believes, explaining that farmed salmon probably ingest the substance when the fish that are exposed to it “bleed” the excess of the substance into the water.
This is shown by an experiment at the IMR, where the findings have not yet been scientifically published.
“If there is poor water replacement, in unfortunate circumstances one may find that the amount of tralopyril is concentrated to a level above lethal for fish inside a cage,” said Grøsvik.
Tralopyril inhibits the function and energy production of the mitochondria in the cells, which prevents energy uptake and leads to oxidative stress.
This makes the researchers suspect that the substance may, at some levels, have a harmful effect on the fish’s gills.
“We have not been able to investigate this yet, but it may be close to believe that when the fish swim around in high concentrations, it will affect the gills negatively,” he added.
Socorex needle
What makes a good needle?
In the agricultural and veterinary fields, the quality and design of injection needles play a pivotal role in ensuring effective and ethical handling of animals. A good injection needle is one that not only serves its intended function with precision but also minimises discomfort for the animal and reduces the risk of injury to both the animal and the handler.
In a recent blog, Swiss precision dosing specialist Socorex spelled out the key factors when looking for the right needle for an agriculture or aquaculture application.
The company advises:
• Opt for high-quality stainless-steel needles (stainless steel specification 304 or 316) due to their durability, corrosion resistance, and sharpness.
• Choose appropriate length, diameter, and bevel design based on injection type, animal size, and skin type for effective and comfortable injections
• Ensure needles are securely packaged to prevent contamination. Packaging should be easy to handle for quick and efficient use.
• Handle needles carefully to avoid breakage, bending, and infection. Adhering to manufacturer recommendations and undergoing regular training are essential for user safety and animal welfare.
