Mowi Scotland looks at scaling up CleanTreat use after trial success

Fish farmer Mowi Scotland and aquaculture biotechnology company Benchmark are looking at larger scale use of Benchmark’s CleanTreat water filtration technology in conjunction with lice treatments after a successful trial earlier this year.

In the trial supported by the Sustainable Aquaculture Innovation Centre (SAIC), the companies used a bespoke CleanTreat system to remove residues of the lice medicine Salmosan Vet (azamethiphos) from water used in bath treatments of salmon.

Salmosan, supplied by Benchmark, is currently used in a “bath” made by enclosing a salmon pen with a tarpaulin and adding the medicine to the water. Once the treatment is complete, the tarpaulin is removed, and the treatment water is released into the surrounding water.

This method limits the amount of Salmosan that can be used, and the speed of treatments.

Final reports

Lice treatments involving CleanTreat were carried out in a bespoke vessel, with the fish returned to the net pen and the water transferred to the CleanTreat system.

Mowi Scotland technical director Dougie Hunter said: “The SAIC trial at our farms has now been completed and we are awaiting final reports.

“We were very encouraged by the initial results and are now evaluating how this might be scaled up and applied in our production systems. As evidenced in the trials, the main advantages of a CleanTreat / Salmosan combination could be to use this system at some of our farms which have limited discharge consents for this product, and to treat farms in shorter time.”

Benchmark spokesperson Rachel Aninakwah said the trial, which also involved Stirling University’s Institute of Aquaculture, had promising results and good collaboration between all partners, and that Benchmark was evaluating the results of the trial and its next steps.

Reduced footprint

Heather Jones, chief executive of SAIC, said: “We are very pleased to see positive results emerging from such an important project. The use of medicines in aquaculture is already tightly controlled and regulated, but they are a crucial part of the range of approaches we need to have to tackle the continuing challenge of sea lice.

“Initiatives like the trial of CleanTreat are a great example of how we can bring aquaculture expertise together to reduce the environmental footprint of the sector, while increasing its contribution to Scotland’s economy.”

CleanTreat was developed to be used in conjunction with Benchmark’s novel lice treatment, Ectosan Vet, but that does not yet have approval for use in the UK. Norway and the Faroe Islands are currently the only countries to have authorised Ectosan Vet, although Benchmark intends to roll it out to all salmon farming countries.

CleanTreat can be used to filter out residues of a range of chemicals, and also removes organic material from the treatment water, including sea lice and sea lice egg strings, which helps prevent development of resistance against treatment medicines.