Re­search round-up

Fish Farmer - - Contents - BY DR SAM HOUS­TON

PHARMAQ’S an­nual knowl­edge trans­fer event, Phar­maqademy, saw a record num­ber of del­e­gates gather at the King­mills ho­tel in In­ver­ness at the be­gin­ning of Novem­ber. The two-day con­fer­ence, di­rected by Pharmaq sales man­ager Chris Mitchell, opened with the com­pany’s Elise Hjelle up­dat­ing the au­di­ence on the progress of Smoltvi­sion in RAS aqua­cul­ture.

Smoltvi­sion is an an­a­lyt­i­cal tool which pro­vides an in­sight into the pro­gres­sion of smolti­fi­ca­tion, the phys­i­o­log­i­cal process by which young salmon in fresh­wa­ter trans­form them­selves for the marine part of their life­cy­cle.

This molec­u­lar tool uses RT-qPCR (quan­ti­ta­tive re­verse tran­scrip­tion poly­merase chain re­ac­tion) to mea­sure the ex­pres­sion of fresh­wa­ter and salt­wa­ter ATPase, as well as a co-fac­tor in the gills of smolts, prior to trans­fer.

Typ­i­cally, farm­ers will sup­ply 20 fresh­wa­ter smolt sam­ples to Pharmaq An­a­ly­tiq to as­sess the ‘readi­ness’ of the pop­u­la­tion for trans­fer to sea­wa­ter. The co-fac­tor’s ex­pres­sion gives an in­sight into over­all gill health, which can pro­vide an en­hanced un­der­stand­ing of the stocks’ sta­tus.

The data col­lected over the years has given the com­pany an ex­cel­lent view of the phys­i­ol­ogy of smolt­ing salmon. Fish liv­ing in fresh­wa­ter, es­pe­cially in RAS aqua­cul­ture, can un­dergo mul­ti­ple smolti­fi­ca­tion events, fol­lowed by a re­ver­sal of the process if the fish are not trans­ferred to salt­wa­ter.

A range of en­vi­ron­men­tal cues can trig­ger an un­planned smolti­fi­ca­tion, the most com­mon of which is salt ex­po­sure, some­times used to in­duce the event.

How­ever, Hjelle in­di­cated that trans­fer­ring fish to a lighter tank can also trig­ger early smolti­fi­ca­tion. Un­planned smolti­fi­ca­tions make it more dif­fi­cult for farm­ers to syn­chro­nise the process across the pop­u­la­tion.

Ju­lia Tand­berg, one of the R&D sci­en­tists at Pharmaq, then gave an up­date on the oc­cur­rence of new vari­ants of Moritella vis­cosa, the causative agent of win­ter sores in farmed salmon, cod and lump­fish in Nor­way and Scot­land.

Han­dling or in­juries can in­crease the risk of in­fec­tion that can lead to the de­vel­op­ment of ul­cers. The preva­lence of this dis­ease in both Nor­way and Scot­land has led to the rapid in­crease in the up­take of vac­cines for Moritella, with 90 per cent of farmed salmon now us­ing them in Nor­way.

How­ever, sur­veil­lance of Moritella has in­di­cated that about 90 per cent of iso­lates col­lected are new vari­ants and Tand­berg pos­tu­lated that vac­ci­na­tion may have rapidly se­lected for them. Phy­lo­ge­netic trees from Moritella iso­lates formed three groups and ELISA (en­zyme linked im­munosor­bent as­say) cross-re­ac­tiv­ity test­ing showed that some vari­ants can be con­trolled by cur­rently avail­able vac­cines, while oth­ers can­not.

Although the group had not in­ves­ti­gated so many Scot­tish iso­lates, the pres­ence of new vari­ants has

“The low in­clu­sion rates of marine ma­te­rial in di­ets were sug­gested as a pos­si­ble risk fac­tor in de­for­mity”

been con­firmed here, but not to the same ex­tent as in Nor­way. In Scot­land, ap­prox­i­mately 75 per cent of fish are vac­ci­nated against Moritella.

Tand­berg asked Scot­tish pro­duc­ers at the con­fer­ence to send sam­ples so she could bet­ter char­ac­terise the bug in Scot­land.

Two speak­ers, Bernt Martin­sen, Zoetis’ group sales direc­tor, and Ane Sandtrø, se­nior man­ager, Out­comes Re­search, Zoetis In­ter­na­tional Op­er­a­tions at Pharmaq, then fo­cused on vac­cines and as­so­ci­ated risk fac­tors that can lead to de­formed ver­te­brae in salmon.

Pharmaq of­fers a vac­cine against pan­creas dis­ease (PD),AL­PHA JECT mi­cro 1 PD, which can be de­liv­ered to pre-smolts along­side other vac­cines.

But as with other com­mer­cial PD vac­cines, the vac­cine may be a risk fac­tor for some newly de­scribed ver­te­bral de­for­mi­ties, which ap­pear to be sig­nif­i­cantly more com­mon in Nor­way than in Scot­land.

Use of func­tional feeds has been pro­posed as a risk fac­tor as­so­ci­ated with ver­te­bral de­for­mity and re­sults from clin­i­cal field stud­ies in­di­cate a con­nec­tion here. How­ever, other stud­ies have been in­con­clu­sive.

Fol­low­ing the pre­sen­ta­tions, dis­cus­sions turned to po­ten­tial nu­tri­tional as­pects as­so­ci­ated with de­for­mity.The low in­clu­sion rates of marine ma­te­rial in di­ets were sug­gested as a pos­si­ble risk fac­tor, which might ex­plain the cur­rent dif­fer­ence in ob­served de­for­mity lev­els be­tween Nor­way and Scot­land.

The fi­nal talk on the first day was given by Clau­dia Tschesche, Pharmaq’s spon­sored PhD stu­dent at the Uni­ver­sity of Stir­ling. She pre­sented an up­date on her work on re­sis­tance in sea lice to deltamethr­in, a syn­thetic pyrethroid which Pharmaq mar­kets as AMX, a bath treat­ment for this par­a­site.

In in­sects, knock-down re­sis­tance (kdr) to deltamethr­in has been de­scribed as a mu­ta­tion which dis­rupts the mol­e­cules’ abil­ity to bind to the tar­get site in volt­age gated sodium chan­nels.

In the salmon louse, how­ever, the tar­get site is un­known, although emerg­ing ev­i­dence sug­gests that mu­ta­tions in the mi­to­chon­drial genome may play a role.

Tschesche is cur­rently ex­am­in­ing pos­si­ble mark­ers in the mi­to­chon­drial genome which pre­dict for re­sis­tance and, in do­ing so, gain a bet­ter un­der­stand­ing of the mech­a­nism. Last year, she pre­sented ev­i­dence show­ing that deltamethr­in re­sis­tance is ma­ter­nally in­her­ited in sea lice and closely linked to four mi­to­chon­drial sin­gle nu­cleo­tide poly­mor­phisms (SNPs) that are pro­tein mod­i­fy­ing.

Fur­ther­more, a Nor­we­gian study has shown that two of these mu­ta­tions are lo­cated on the sur­face of these pro­teins, pro­vid­ing the pos­si­bil­ity that deltamethr­in may bind at these sites to ex­ert a toxic ef­fect.

Her ex­per­i­ments lend fur­ther weight to this hy­photh­e­sis. By ex­pos­ing deltamethr­in re­sis­tant lice to the in­sec­ti­cide etofen­prox, she found that these lice were fully sus­cep­ti­ble to this com­pound. Had their re­sis­tance to deltamethr­in been me­di­ated through kdr mu­ta­tions, then this should also have pro­tected them against etofen­prox – no such pro­tec­tion was ob­served and by ex­ten­sion kdr is not the mech­a­nism of pro­tec­tion in lice that are re­sis­tant to deltamethr­in.

The second day of pre­sen­ta­tions was opened by Jamie Bran­nan, vice pres­i­dent of Zoetis UK, Pharmaq’s par­ent com­pany. He gave a high-level per­spec­tive of Zoetis’ in­no­va­tion of­fer­ing in the rapidly chang­ing an­i­mal health mar­ket place. Zoetis op­er­ates glob­ally, with an­nual rev­enues of $5.8 bil­lion; of its 10,000 staff, 1,100 are in­volved in re­search and de­vel­op­ment.

The com­pany has iden­ti­fied three key global driv­ers of growth: ris­ing pop­u­la­tion, a grow­ing mid­dle class, and a rise in pet ‘med­i­cal­i­sa­tion’ and pro­tein con­sump­tion (12 per cent meat and 30 per cent fish) by 2026.

He ex­plained that Zoetis’ mis­sion state­ment is to pro­vide a ‘con­tin­uum of care’ to farm and com­pan­ion an­i­mals.The tools and ser­vices pro­vided aim to pre­dict and fore­cast an­i­mal health, pre­vent any dis­tur­bances to health, as well as of­fer a range of treat­ment op­tions if it is com­pro­mised.

Lucy Wil­liamson, an in­de­pen­dent hu­man nu­tri­tion­ist, said the aim of her nutri­tion ser­vices is to pro­vide sim­ple ev­i­dence based ad­vice. Her talk fo­cused on fish con­sump­tion from the omega-3 per­spec­tive, but also as a source of io­dine, vi­ta­min D and se­le­nium.

One as­pect of hu­man nutri­tion which is of con­cern, she said, is the cur­rent trend to­wards veg­e­tar­i­an­ism and ve­g­an­ism, par­tic­u­larly in chil­dren who are still grow­ing rapidly.

Wil­liamson said that sur­veys of the pop­u­la­tion in­di­cated that most peo­ple do not con­sume the two rec­om­mended por­tions of oily fish each week, and that con­sump­tion of long-chain omega-3 fatty acids was too low.A lack of aware­ness about cook­ing fish was of­ten cited as a cause of this.

Although veg­etable oils do con­tain omega-3, it is in the form of ALA which must then be con­verted into EPA and DHA, the same ben­e­fi­cial oils found in oily fish.This process re­quires en­zymes which share the omega-6 meta­bolic path­way; be­cause there tends to be far more omega-6 in our diet nat­u­rally, the omega-3 path­way is dis­ad­van­taged.

Eat­ing fish al­lows us to ben­e­fit from a di­rect source of EPA and DHA, cru­cial to our long-term health.The omega-6 to omega-3 ra­tio in the UK diet is es­ti­mated to be about 10:1, a long way from the 2:1 rec­om­mended by WHO or even the 6:1 which has of­ten been used as a re­al­is­tic tar­get!

Con­tin­u­ing the theme of nutri­tion, but from the per­spec­tive of the fish, Chloe Phan Van Phi from In­nova Feed, a French com­pany lead­ing the way in the man­u­fac­ture of in­sect de­rived prod­ucts, out­lined the com­pany’s use of agri­cul­tural by-prod­ucts to pro­duce an in­sect pro­tein meal, an in­sect oil and a rich or­ganic fer­tiliser as by-prod­uct from the ‘frass’ (what’s left af­ter a pro­duc­tion cy­cle).

In­nova Feed is work­ing closely with Cargill to in­ves­ti­gate the use of these ma­te­ri­als in salmon di­ets.

The com­pany will open the world’s largest in­sect rear­ing plant in 2020, ca­pa­ble of pro­duc­ing 15,000 tonnes of in­sects each year.The fac­tory will be co-lo­cated with a Tereos op­er­ated starch and sweet­en­ers mill and Ko­ge­ban, a biomass tur­bine.

This will al­low In­nova Feed to ex­ploit ex­cess heat and by-prod­ucts from the mill, as well as cap­ture so-called ‘fa­tal’ en­ergy from the tur­bine nor­mally dis­si­pated into the at­mos­phere, lead­ing to a re­duc­tion in car­bon emis­sions of 35,000 tonnes each year.

Other ini­tia­tives to de­velop the mar­ket in­clude work­ing with chefs and fish mon­gers to spread the con­cept of rear­ing fish us­ing in­sects and ob­serv­ing how this is re­ceived by the con­sumer.As part of this process a new la­bel has been de­vel­oped, ‘Pois­son nourri à l’in­secte’,‘fish fed with in­sects’, to sup­port the new sec­tor’s laud­able am­bi­tions to con­trib­ute to a more cir­cu­lar econ­omy.

Arno Schut from Ax­en­tive changed fo­cus with a pre­sen­ta­tion on the use of Halamid (Chlo­ramin T), as a gen­eral pur­pose dis­in­fec­tant. In aqua­cul­ture, the com­pound is typ­i­cally used as an in-wa­ter dis­in­fec­tant rather than for the ster­il­i­sa­tion of plant and equip­ment, as is the case in other types of an­i­mal pro­duc­tion. Data were pre­sented show­ing how the com­pound could be used suc­cess­fully with­out any hin­drance to biofil­ter func­tion.

Ster­il­i­sa­tion of fish stock rather than fish farms was the theme of Deb­bie Plouffe’s pre­sen­ta­tion. She had trav­elled from the Cen­tre for Aqua­cul­ture and Tech­nolo­gies in Canada to talk about gene edit­ing tech­nolo­gies cur­rently un­der de­vel­op­ment.

Im­por­tantly, she ex­plained that gene edit­ing was

“The cur­rent trend to­wards veg­e­tar­i­an­ism and ve­g­an­ism is of con­cern, par­tic­u­larly in chil­dren who rapidly” are still grow­ing

not the in­tro­duc­tion of new ge­netic ma­te­rial into an or­gan­ism but rather the edit­ing of in­cum­bent genes us­ing the CRISPRR/cas9 sys­tem on de­vel­op­ing fish em­bryos.

One ex­cit­ing as­pect of these tech­nolo­gies is that breed­ing pro­grammes can be rapidly ac­cel­er­ated if the de­sired al­ter­ations to genes are un­der­stood.

How­ever, Plouffe was keen to em­pha­sise that gene edit­ing is com­ple­men­tary to tra­di­tional breed­ing pro­grammes and not a sub­sti­tute.

Work­ing with tilapia as a model, the com­pany has de­ployed the tech­nol­ogy to gen­er­ate ster­ile fish. These in­di­vid­u­als are bi­o­log­i­cally sim­i­lar to their par­ents in all as­pects ex­cept go­nad de­vel­op­ment and there­fore do not en­counter the prob­lems some­times as­so­ci­ated with the more tra­di­tional method of ster­il­i­sa­tion, triploidy.

For now, how­ever, these tech­nolo­gies will re­main largely in the Amer­i­cas, un­less ac­com­mo­dat­ing reg­u­la­tory re­form is forth­com­ing in Europe.

The fi­nal topic of Phar­maqademy’s agenda was plas­tic pol­lu­tion, with Chris Walkin­shaw, a PhD stu­dent from Ply­mouth Marine Lab­o­ra­tory, out­lin­ing the scale and im­pacts of the problem.

He was fol­lowed by Cather­ine Mor­ri­son, of Ire­land’s Seafood De­vel­op­ment Agency (BIM), who in­tro­duced the Clean Oceans Ini­tia­tive’s pro­pos­als aimed at man­ag­ing it.

Walkin­shaw’s work ex­am­ines the im­pact of plas­tic pol­lu­tion within the con­text of food se­cu­rity. A broad over­view showed how mi­croplas­tics can now be found ev­ery­where in the aquatic en­vi­ron­ment.

Ar­eas of con­cern within aqua­cul­ture in­clude the ad­sorp­tion of PCBs, PAHs, diox­ins and heavy me­tals on to mi­croplas­tics. Harm­ful species of al­gae can even be trans­ported across the ocean on plas­tic par­ti­cles.

Go­ing for­ward, he will fo­cus his stud­ies on mus­sels to an­a­lyse the pres­ence and char­ac­ter­is­tics of mi­croplas­tics in­side these an­i­mals, gen­er­at­ing data to sup­port the shell­fish sec­tor with their risk analy­ses.

He will also ex­am­ine fish­meals to quan­tify the level of plas­tic pol­lu­tion in them. He said that the smaller the par­ti­cle size be­ing searched for, the greater the amount of plas­tic that would be found.

Mor­ri­son in­formed the au­di­ence that sim­ple ac­tions could be de­ployed to ‘turn off the tap’, to stem the con­stant flow of plas­tics into the aquatic en­vi­ron­ment.

She also ex­plained, the myr­iad forms that plas­tic can take, and the com­plex­i­ties as­so­ci­ated with re­cy­cling the ma­te­rial, es­pe­cially the sep­a­ra­tion re­quired due to the va­ri­eties of type and den­sity.

She went on to ex­plain how BIM had worked with fish­er­man in the ‘Fish­ing for Lit­ter’ scheme. The project pro­vides sacks on the decks of fish­ing ves­sels to col­lect plas­tic items that are hauled in with the catch.

Ap­prox­i­mately 80 per cent of Ir­ish trawlers have signed up to the scheme and are bring­ing lit­ter ashore. Fish farm­ers also con­trib­ute by or­gan­is­ing shore and pier clean-ups in their lo­cal ar­eas.

How­ever, the work has not stopped there; re­cy­cling the ma­te­ri­als is com­plex and in­volves sort­ing and clean­ing (salt con­tam­i­na­tion makes them largely unattrac­tive to re­cy­clers).

Nev­er­the­less, the project cleans and sorts as much as pos­si­ble and a large mo­bile shred­der has been de­ployed to help com­press and man­age the large quan­ti­ties that are re­cov­ered from the sea.

Mor­ri­son said that although these types of schemes have ad­di­tional ben­e­fits, specif­i­cally to do with sat­is­fy­ing so­cial con­science, more needed to be done to stop the huge quan­ti­ties of waste be­ing pro­duced in the first place.

Such mea­sures would re­quire a co­or­di­nated global ef­fort and in­volve reg­u­la­tion and ex­ten­sive mod­i­fi­ca­tion of sup­ply chains.

The con­fer­ence, held on Novem­ber 4-5, fin­ished with lunch and fur­ther net­work­ing.The au­thor would like to thank Pharmaq for or­gan­is­ing such an in­for­ma­tive and in­ter­est­ing event, for their hos­pi­tal­ity and the chance to try curl­ing!

Above left: Clau­dia Tschesche and Chris Mitchell Above right: Del­e­gates at this year’s Phamaqadem­y Op­po­site: Chloe Phan Van Phi of in­sect pro­tein pioneer In­nova Feed

Above: Zoetis UK vice pres­i­dent Jamie Bran­nan and Chris Mitchell

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.