9 minute read
Fish health
Sea lice, viral and bacterial infections, and gill health were all issues for fish farming this year
In January, mandatory reporting of sea lice numbers moved to a weekly basis for Scottish fi sh farmers.
An Order was laid in the Scottish Parliament in December introducing what the Scottish Government call a “step change” in sea lice reporting. It requires average weekly female sea lice numbers per fi sh to be reported one week in arrears, in place of current arrangements, which require reporting only where specifi c levels are met or exceeded.
The policy was fl agged up earlier in December by (then) Cabinet Secretary for Rural Economy and Tourism Fergus Ewing, while giving evidence to the Scottish Parliament’s Rural Economy and Connectivity Committee.
As previously, the Fish Health Inspectorate sea lice reports will be available in spreadsheet format via the Scottish Government website.
Also in January, we reported that fi sh health company PatoGen Ltd is to set up a laboratory for preventive and diagnostic services in Oban, Scotland. The move by the Norwegian company is part of its expansion into the UK, which started in 2014. PatoGen established its offi ce at the SAMS campus in Oban in August 2018.
Dr Teresa Garzon, PatoGen’s key account manager for the UK, said: “It is an excellent collaboration, and the proactive farmers’ focus on maintaining good fi sh health and welfare allows us to commit to the next step in PatoGen’s establishment in the UK.” Meanwhile, a novel virus in ballan wrasse hatchlings could be the cause of unexplained high mortality for hatchlings, according to PatoGen.
The Norwegian-based company has named the virus Ballan wrasse birnavirus (BWDV). PatoGen worked with a fi sh farmer to investigate diseased fi sh for relevant pathogens and histology, and performed a full genome sequencing in which researchers found the genome of the novel
This page from top: Dr Teresa Garzon; Ballan wrasse; PatoGen test tube Opposite: Benchmark CleanTreat tanks
birnavirus. Downstream PCR studies detected large amounts of virus in fi sh larvae from groups with increased mortality. PatoGen believes that biosecurity measures against BWDV will reduce the mortality in this critical phase of the ballan wrasse production. The mortality for wrasse occurs after a short period of loss of appetite, and peak mortality typically occurs between days 17 and 25 post hatching (DPH). Samples from fi sh at the farm were collected weekly from hatching and were examined with PCR for relevant pathogens and histology. The genome sequencing analysis revealed high amounts of gene sequences of a novel virus grouped within the virus family Birnaviridae. The gene sequences of the novel Ballan wrasse virus were genetically diff erent from other known birnaviruses and aquabirnaviruses. The best known birnavirus in Norwegian aquaculture is infectious pancreatic necrosis virus (IPNV), an aquabirnavirus known to cause fry mortality in Atlantic salmon. Other birnaviruses are associated with early fry mortality on other marine fi sh species. The investigation showed that the virus infection is maintained in the population for a long time after the peak mortality and at high levels. PatoGen is now off ering fi sh growers a PCR analysis for the Ballan wrasse birnavirus. In February, we reported that Norway had recorded its fi rst confi rmed case of infectious salmon anaemia (ISA) at a fi sh farm owned by family business Elilsen Fisk, at Namsos in the Trøndelag region. Fish in the cages aff ected were culled. It was not to be the last case of ISA in Norway. Further outbreaks were recorded in Nordland in May, and at the Midt-Norsk Havbruk farm site at Kvingra in central Norway, as well as a Norway Royal Salmon site in the Troms and Finnmark region. In March, Benchmark Holdings announced that it was rolling out its new CleanTreat sea lice solution in the second quarter of 2012. The new treatment system combines Benchmark’s BMK08 lice treatment with the CleanTreat fi ltering system, which fi lters out all measurable traces of the chemical after application, as well as capturing any strings of sea lice eggs. Field trials of the system in Norway had proved very successful, the company said. The system was granted marketing authorisation by the Norwegian Medicines Agency in July, clearing the way for it to be rolled out to its fi rst commercial customers over the
rest of the summer.
The European Commission had also set a maximum residue limit (MRL) for BMK08, aollwing its use on salmon destined for sale in the European Union, and the Norwegian Parliament in term ratifi ed that decision.
It was not all plain sailing, however. BMK08, otherwise known as Ectosan, is based on the pesticide imidacloprid, which has been described as “novichok for insects” and in June its use was condemned by members of the European Parliament. It remains to be seen whether the MEPs will be able to override the Commission or whether Ectosan will turn out to be a game changer in the battle against sea lice.
In April, Mowi announced the promotion of Meritxell Diez-Padrisa to the post of Fish Health Director. She was previously Production Director, Scotland. In her new role she is responsible for overseeing fi sh health programmes for the group in health programmes for the group in all regions. all regions.
Meanwhile, aquaculture tech business Manolin said that trials of business Manolin said that trials of its fi sh health prediction application its fi sh health prediction application showed that it was accurate to showed that it was accurate to 93%. 93%.
Manolin’s software had been tracking health challenges for salmon ing health challenges for salmon farmers across Norway. It uses mafarmers across Norway. It uses machine learning to predict the early onset of pancreas disease and infectious salmon anaemia based on a range of data inputs, and is the only commercially available disease-forecasting tool for farmers in Norway.
The company’s Chief Technology Offi cer and co-founder, John Costantino, said: “This is a true breakthrough moment for our company and the industry as a whole.” In May, one of the bestknown names in aquacultural health changed as Fish Vet Group became Pharmaq Analytic, following the company’s acquisition by Pharmaq’s parent company, Zoetis, in July last year.
Operations Director Chris Matthews said: “We are proud that for 25 years our team has led the way in developing aquatic veterinary,
MANOLIN SAID THAT TRIALS OF ITS FISH HEALTH PREDICTION APPLICATION SHOWED THAT IT WAS ACCURATE TO 93%
diagnostic and environmental approaches in the United Kingdom and Ireland. Going forward as Pharmaq Analytiq, we are excited to be able to honour that heritage of innovation with the additional resources that [come with] being part of Pharmaq and Zoetis.”
Scottish Sea Farms (SSF) celebrated a health milestone, recording zero use of antibiotics for its marine farms and hatcheries. The company said it had kept its marine sites antibiotic-free since 2012, but 2020 was the fi rst year it had also managed to extend that to its hatcheries.
The company said a “holistic” approach to fi sh welfare had made it possible. Ronnie Soutar, Head of Veterinary Services at SSF, said: “We’re very proud to have reached this stage. It is important on a global scale that antibiotic use is minimised and only used when absolutely essential.” In June, we reported that Norway was facing an additional viral threat, following reports that infectious hematopoietic necrosis (IHN) had been detected in Denmark and Finland. Although it had not shown up in Norway, there were fears that it could spread via the import of live fi sh and fi sh products. Norway’s Veterinary Institute remained on high alert.
In Denmark, meanwhile, the trade association Dansk Akvakultur and the six farms aff ected by the outbreak drew up a plan, which they presented to the Danish Veterinary and food Administration, setting out how the country could return to IHN-free status
Meanwhile, in Chile, one of the country’s biggest salmon producers, Salmones Camanchaca, estimated that the harmful algal blooms that struck the country’s coast in March had cost it at least US$12m (£8.52m).
Opposite from top: Meritxell Diez-Padrisa; John Costantino; Chris Matthews; Manolin app Above: Scottish Sea Farms Barcaldine smolt In June, we reported that Norway
Camanchaca reduced its harvest estimates from 55,000–57,000 tonnes to 41,000–44,000 tonnes. Around 3,700 tonnes had been lost to the algal blooms.
In September, we reported on a study being launched by a team of researchers in the UK to fi nd better ways to vaccinate ballan wrasse against the bacterium Aeromanas salmonicida. The consortium included the University of Stirling’s Institute of Aquaculture, Mowi, Otter Ferry Seafi sh, Ceva Ridgeway Biologicals and the Sustainable Aquculture Innovation Centre.
In October, as fi sh health is an international issue, experts from around the world took part in an online conference on gill health, which is emerging as a substantial threat. The International Gill Health Conference cast a light on the problems of amoebic gill disease and complex gill disease, where a number of factors are combined.
One of the important conclusions was that it is essential that farmers are aware of the state of health of their stock before applying any treatment for another condition, such as sea lice, as fi sh with poor
gill health may not survive such treatment.
As reported by Mowi Scotland’s Regional Health Manager, Lucy Fry, hydrozoans – also known as “micro jellyfi sh” – are increasingly being recognised as a source of gill health problems.
The Conference was organised by SAIC Events, in collaboration with the Norwegian Seafood Research fund, BioMar, Aqua Pharma, Mowi, Cargill, PatoGen and Salmon Scotland.
Above: Salmones Camanchaca Left: Lucy Fry
