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

The Herald - - Environmen­t -

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

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