The Herald

Sea lice could be eradicated by new treatment at salmon farms

A vaccine aims to protect fish and the environmen­t in battle to beat threat to industry, Rohese Devereux Taylor reports

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A PIONEERING oral vaccine that will treat sea lice in farmed Atlantic salmon is in developmen­t after receiving a funding boost.

The new treatment, produced by a team of Scottish and internatio­nal aquacultur­e experts, aims to help the industry tackle one of the biggest threats to the welfare of farmed Atlantic salmon, as well as eliminate environmen­tal toxins.

Sea lice are a constant challenge for the global aquacultur­e industry. Some traditiona­l chemical treatments also pose a threat to the environmen­t.

The two-year project, supported with £260,000 funding provided through the Scottish Aquacultur­e Innovation Centre (SAIC) and matched by the industry, began in July, developing the treatment which can be delivered through fish feed with minimal disturbanc­e.

The cost of sea lice to the Atlantic salmon production industry is estimated to exceed £50 million per year in Scotland alone.

Project partners include academics from the University of Stirling‘s Institute of Aquacultur­e as well as industry specialist­s from the global fish feed producer Biomar, nanopartic­le company Sisaf and vaccinolog­y experts Tethys Aquacultur­e. The consortium also draws upon the expertise of vaccinolog­ists at the Moredun Research Institute and academic fish immunologi­sts from the University of Maine in the United States.

Polly Douglas, aquacultur­e innovation manager at SAIC, said: “Addressing environmen­tal and health challenges, including sea lice, is one of SAIC’S priority innovation areas and a crucial concern for the global aquacultur­e industry. The work of this project correlates directly with the Scottish Government’s 10-year Farmed Fish Health Framework, aiming to improve fish health, protect the marine environmen­t, and ensure Scotland’s main food export grows sustainabl­y.

“Collaborat­ive research and developmen­t projects, such as this, harness the expertise of academia, industry partners and salmon producers, and can play a major role in future sustainabi­lity of the industry.”

Ms Douglas told The Herald that, while vaccinatio­ns are used in the industry, usually for bacteria or viruses, the method is much less common for use against a complex parasite like sea lice.

The parasites are currently managed and controlled using a range of measures, including veterinary medicines, physical and biological tools for parasite removal, and optimised farm management practices. Despite existing research and prior testing of injectable vaccines, success has so far been limited, with no commercial solution currently available. Veterinary medicines continue to be employed for control. However, sea lice are becoming increasing­ly resistant to treatment.

In the last 40 years a number of treatments have become available.

Previous dip vaccines were absorbed through the salmon’s gills, while hydro and thermal licers used water pressure and warmer water to treat the lice.

Ms Douglas said: “Sea lice are very canny. They become resistant to treatment so it becomes less effective. Different medicines have come and gone. There have been in-feed treatments before and bath treatments where fish are put into smaller areas and the sea lice treatment is put into the water.

“A lot of treatments can stress fish and we’re trying to reduce that. This new vaccine could reduce handling of the fish, and them being taken out of the water. It would be put into their feed and improve their welfare. We’re working away from chemical treatments as they have an impact on the wider environmen­t.”

Cleaner fish, including lumpfish and wrasse, are used to nibble lice from the salmon, a natural solution that is encouraged in the farms.

The new approach to oral vaccinatio­n will deliver the vaccine via specially developed feeds that aim to improve fish resistance to parasites using advanced nanopartic­le technology. Bio-engineerin­g tools will also target sea lice by triggering strong immune responses in the skin of fish, rather than delivering it through the bloodstrea­m alone. Sharing approaches employed to control ticks in agricultur­e, the new vaccine aims to target proteins important for the parasite’s survival.

Dr Sean Monaghan, from the Institute of Aquacultur­e at the University of Stirling, said: “Reducing the impact of sea lice is a major concern for salmon producers around the globe and we are making headway towards finding an effective method for vaccinatin­g fish against this parasite. There is strong evidence to support the use of an oral vaccinatio­n, using nanopartic­les in feed for vaccine delivery in order to trigger the desired antibody response.”

A lot of treatments can stress fish and we’re trying to reduce that

 ??  ?? Fish farms face the constant challenge of keeping their fish free from sea lice as the pest can become resistant to treatments
Fish farms face the constant challenge of keeping their fish free from sea lice as the pest can become resistant to treatments
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