Mowi’s Paul Fletcher as­sesses Phar­maq’s SmoltVi­sion

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Vi­sion for smolt

IN an in­ter­view with Fish Farmer, Paul Fletcher, man­ager at Mowi’s Lochailort hatch­ery, shares his views on SmoltVi­sion, the new tool from Phar­maq An­a­ly­tiq de­signed to help man­agers as­sess the readi­ness of their smolts for trans­fer to sea­wa­ter.

Fish Farmer: How long have you been work­ing at Lochailort? Paul Fletcher: I have been work­ing at Lochailort for just over 11 years, five at the old site here and the rest at the new unit.

FF: And roughly how many fish are taken through to the smolt stage at the site? PF: We smolt ap­prox­i­mately five mil­lion fish per year here at Lochailort. FF: His­tor­i­cally, what meth­ods have you used to as­sess your stock’s readi­ness for trans­fer to sea water? PF: The way we have as­sessed the readi­ness of the stocks is nor­mally through ATPase sam­pling which is done through our own labs. Blood chlo­rides are also some­times taken.

FF: It has been said that as­sess­ing readi­ness for trans­fer to sea­wa­ter is more chal­leng­ing in fish raised in re­cir­cu­lat­ing aqua­cul­ture sys­tems (RAS) than those reared in flow through or fresh­wa­ter loch sys­tems. What is your view on this? PF: It cer­tainly can be more of a chal­lenge to get the tim­ing just right to trans­fer the smolts from a RAS sys­tem; over the years we have seen the smolt­ing process be­come quicker, with us now look­ing at the fish to be smolted around 300350 days, whereas at the fresh­wa­ter loch sites we seem to be steadily achiev­ing this at 400450 days. We are try­ing to hit a small win­dow where all the fish are at their op­ti­mal trans­fer point si­mul­ta­ne­ously to en­sure a good trans­fer with very lit­tle mor­tal­ity, and where the fish can take off in their new en­vi­ron­ment at sea.

FF: You have re­cently tried out Phar­maq An­a­ly­tiq’s SmoltVi­sion tool to as­sist you in your as­sess­ment of your stock’s fit­ness for trans­fer. Can you tell us a lit­tle about how this works? PF: SmoltVi­sion ba­si­cally mon­i­tors the ATPase ac­tiv­ity of two ion pumps (pump in/pump out) lo­cated in the gill lamel­lae. As smolts tran­si­tion from a life in fresh­wa­ter to one in the sea they must switch from ac­tively tak­ing ions in from the en­vi­ron­ment to ac­tively ex­cret­ing them out. This ac­tive process is me­di­ated by ATPase, for which there is a fresh­wa­ter iso­form in the first in­stance and a sea­wa­ter one in the sec­ond.

By test­ing 20 fish over three points in time, the shift from fresh­wa­ter ATPase ac­tiv­ity (in­ward pump­ing) to sea­wa­ter ATPase ac­tiv­ity (out­ward pump­ing) can be mon­i­tored. Be­cause the mea­sure­ment is ac­tu­ally done at the gene

level, this pro­vides a pre-warn­ing of a func­tional shift in ion pump ac­tiv­ity sev­eral days in ad­vance of it hap­pen­ing. In ad­di­tion to this, Phar­maq An­a­ly­tiq is able to mon­i­tor a sup­ple­men­tary marker which it refers to as ‘the co-fac­tor. This can pro­vide use­ful in­for­ma­tion about the pres­ence of po­ten­tially dam­ag­ing in­flu­ences on the gills, in­clud­ing sub­op­ti­mal water qual­ity, pathogens or sim­ply me­chan­i­cal dam­age, all of which can in­ter­fere with the nor­mal smolti­fi­ca­tion process. By track­ing the lev­els of the three mark­ers at three time points in the smolti­fi­ca­tion pe­riod, SmoltVi­sion helps me de­cide, in ad­vance, the op­ti­mum time to trans­fer my fish – a de­ci­sion which, I am acutely aware, fish have evolved to make them­selves!

FF: Given that the anal­y­sis is con­ducted in Nor­way, this must af­fect the speed with which you get the re­sults? PF: The sam­ples are back nor­mally within four to five days from the date sent.

FF: Since us­ing SmoltVi­sion have you no­ticed a ben­e­fit ? PF: Phar­maq An­a­ly­tiq cer­tainly helps by putting the re­sults across in a way that are clear and easy to un­der­stand, giv­ing us the con­fi­dence to trans­fer the fish within the op­ti­mal win­dow for the pop­u­la­tion.

FF: How easy is SmoltVi­sion to use? PF: It is very easy. You sam­ple the gills like you would for a nor­mal PCR gill test, ex­cept that you don’t have to use ster­ile tech­nique, so it is much quicker and less has­sle. You then put the tis­sue in sam­pling tubes pro­vided by An­a­ly­tiq, fill out the forms, and send them back to Ber­gen for anal­y­sis. No need to use dry ice, as the sam­ples are sta­ble enough to ship with only reg­u­lar cool packs. When the sam­ples are an­a­lysed we re­ceive an email no­ti­fy­ing us that the test is com­plete, and that we can ac­cess the re­sults on­line on the con­fi­den­tial Phar­maq An­a­ly­tiq cus­tomer por­tal.

FF: And how do you in­ter­pret the re­sults? PF: We don’t have to. Phar­maq An­a­ly­tiq sends through re­ports from each of the three sam­pling points. The in­ter­pre­ta­tion of SmoltVi­sion re­sults dif­fers a lit­tle from how the re­sults from a reg­u­lar ATPase anal­y­sis are in­ter­preted. In­stead of fo­cus­ing on the spe­cific nu­mer­i­cal value for each fish, SmoltVi­sion fo­cuses on the ra­tio between the sea­wa­ter and the fresh­wa­ter ATPase level. This means that it is not the spe­cific num­ber for each com­po­nent that is im­por­tant, but in­stead the level of sea­wa­ter ATPase com­pared to the level of fresh­wa­ter ATPase. As long as an in­di­vid­ual is show­ing more sea­wa­ter ATPase than fresh­wa­ter ATPase, then it is con­sid­ered sea­wa­ter tol­er­ant. The re­sults from the anal­y­sis are sum­marised in the re­port, with a com­ment de­scrib­ing how many sea­wa­ter tol­er­ant in­di­vid­u­als there are in each sam­pling point.

FF: Do you an­tic­i­pate us­ing SmoltVi­son at Lochailort again? PF: Yes we will be us­ing the SmoltVi­sion test­ing again and I know other sites will also be us­ing the test.

“SmoltVi­sion helps me de­cide, in ad­vance, the op­ti­mum time to trans­fer fish” my

Op­po­site: Talk­ing smolti­fi­ca­tion. From left to right: Hugh McGin­ley, fresh­wa­ter pro­duc­tion man­ager, Mowi Ire­land; Paul Fletcher, Lochailort man­ager Mowi Scot­land; and Elise Hjelle, Phar­maq An­a­ly­tiq. Above: Track­ing sea­wa­ter tol­er­ance: the fig­ure shows data from a sin­gle tank of fish with four sam­pling points in the pe­riod 21.01.19 – 15.02.19. Each sam­pling point in­volves 20 fish. The yel­low field in­di­cates the level of sea­wa­ter ATPase ex­pressed at each sam­pling point, and which in­creases over the sam­pling pe­riod. Once the group has crossed the smolt thresh­old the fish are con­sid­ered sea­wa­ter tol­er­ant. The co-fac­tor is within the nor­mal level of ex­pres­sion, and is thus not in­di­cat­ing any dis­tur­bance of the smolti­fi­ca­tion process for the group in ques­tion. Below: Dif­fer­en­ti­a­tion between sea­wa­ter and fresh­wa­ter (Pic­ture Mc­Cormick et al., 2013a).: These im­ages show im­munolo­cal­i­sa­tion of chlo­ride cells in the gills of wild salmon. The green cells are fresh­wa­ter type cells and the red cells are sea­wa­ter ones. The first im­age shows a fish at the parr stage, adapted to a fresh­wa­ter en­vi­ron­ment and pro­duc­ing mainly the fresh­wa­ter chlo­ride cells (green). Af­ter the on­set of smolti­fi­ca­tion, the fish starts to pro­duce more of the sea­wa­ter type chlo­ride cells (red) as it de­vel­ops sea­wa­ter tol­er­ance. Two weeks af­ter trans­fer, rep­re­sented in the last pic­ture, the fish has fully adapted to sea­wa­ter and is only pro­duc­ing the sea­wa­ter type of chlo­ride cells. Dur­ing the smolti­fi­ca­tion process when the ra­tio between fresh­wa­ter and sea­wa­ter cells will vary, it is im­por­tant to be able to dis­tin­guish between the two types, in order to track the progress of the pop­u­la­tion.

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