Year of grant: 2003 Research Area: Matur Project type: Verkætlan Project title: Støddarbýti, Strongd og IPN hjá laksayngli. Grant number: 0202 Project manager: William Simonsen Institution/company: P/F Fiskaaling Other participants: Marita Næs, laborantur, Heilsufrøðiliga Starvsstovan Debes H. Christiansen, molekylerlívfrøðingur, heilsufrøðiliga Starvsstovan Project period: 1.9.2004 - 1.12.2005 Total budget: Original:668.000 Final: 706.000 Grant from the FRC in DKK: 367.000 kr. Project description: Original description Endamálið við verkætlanini er at: 1. kanna, um samband er millum støddarbýti, strongd og sjúkuútbrot hjá laksayngli og um til ber at fyribyrgja nøring av subkiniskari smittu og at steðga útbroti av laksavirussjúkuni IPN (INfectious Pancreas Necrosis) við at minka um strongd 2. útvega vitan og royndir við at kanna fyri strongd, sum skulu brúkast í gransking og menning og kunnu bjóðast vinnuni og føroyska granskingarumhvørvinum sum heild 3. at gera forkanning av, hvat hendir í yngli, ið verur viðgjørdur ímóti IPN við einum sera effektivum tekniskum viðgerðarhátti, sum Fiskaaling er komið fram á undir arbeiðinum við verkætlanini. Kannað verður, hvussu støddarmunur á laksayngul í somu kørum strongir fiskin. Verður signifikant samband funnið ímillum støddarbýti og strongd, er ætlanin at kanna, hvussu hetta kann ávirka útbrot av IPN. Hartil krevst loyvi til at gera royndir við smittu og ein starvsstova til smittuoroyndir. Søkt verður ikki um fígging til hendan partin, fyrr enn loyvi fyriliggur frá landsdjóralæknanum. IPN elvir til stórt felli og miss á føroyskum smoltstøðum uppá leysliga mett um. 20 mill kr. árliga. Óbeinleiðis missurin av viknaðum fiski, vánaligum vøkstri og viðbrekni yvir fyri øðrum sjúkum kann vera enn størri. Í okkara grannalondum verður IPN mett at vera størsti tapsvoldari í sjógvalingini. Í Føroyum svarar fellið í sjónum til 100-200 mill. kr. ella millum 1/5 og 1/10 av søluvirðinum, men óvist er, hvussu stórur partur av hesum er elvt av IPN, tí lítið er gjørt við at kanna, og einki almannakunngjørt, um hvat føroyski alifiskurin í sjónum doyr av. Koppseting ímóti IPN hevur havt lítið ella einki árin og eingin viðgerð hevur verið alment kend, tó at føroyskir smoltalarar seinnu árini hava roynt seg við einum tekniskum viðgerðarhátti, sum tó ikki kann nýtast á øllum smoltstøðum. Djóralæknarnir tora ikki at viðmæla hesum, fyrr enn viðgerðarhátturin er vísindaliga skjalprógvaður. Undir arbeiðinum við verkætlanini er Fiskaaling komið fram á ein annan tekniskan viðgerðarhátt fyri IPN, sum er effektivur og kann nýtast á øllum smoltstøðum og helst eisini í ungum fiski á sjónum. Hetta er sostatt eitt satt gjøgnumbrot av størsta altjóða áhuga. Tó vita vit ikki, hvat hendir í fiskinum fisiologiskt og immunologiskt. Ætlanin er at royna at útvega fígging og umstøður til at kanna hetta nærri. Sum liður í hesi kanning er ætlanin at gera eina lítla forkanning, ið kann geva ábendingar. Final reporet: During peak production of Atlantic salmon parr (1998-2002), yearly losses due to IPN, most of which occurred in fresh water, were estimated by us to be around DKK 20 mill. Total losses in the sea phase may have been as high as 100-200 mill., but little information is available on the causes, including possible losses due to IPN in the sea phase. No treatment has been available against IPN, and vaccination has been inefficient. During an outbreak in 1986 at P/F Fiskaaling, Atlantic salmon parr were (size)graded during an IPN outbreak. Surprisingly, the mortality seized in tanks already graded but continued unaffected in the remaining tanks, until they were also graded. This did not seem to be a result of lower fish density post grading, as density was generally not reduced. In 2002/3, an experiment was conducted to test, whether reduced size distribution reduced stress in the fish. This did not turn out to be the case, which - contrary to standard perception of the effect of stress on disease - lead to the rather unconventional theory, hatched by production manager Astrid Hansen, that it might be the acute stress induced during grading, which so drastically caused mortality to seize back in 1986. While the data from the first experiment were being analyzed, an outbreak among A. salmon parr allowed successful field testing of this theory, although unfortunately, time, finance, materials and other circumstances did not allow setting up of a new scientific trial at the time. The results of this field trial are presented, seemingly supporting Astrid´s controversial proposal. Planned facilities and authorization to test the theory scientifically by infecting experimental fish didn´t materialize during the course of the project. Instead, after receiving further funding, a test was conducted at Fiskaaling, where healthy and non-infected fish were stressed correspondingly. At the national fish disease laboratory at Heilsufrøðiliga Starvsstovan, serum from stressed and non-stressed fish and IPN-virus were added to CHSE-cells and incubated. Unfortunately, the virus titer changed too rapidly to allow proper assessment between all samples and groups. However, those results, which were comparable, indicated that if representative, there might be a 10 to 100 fold higher serum protection against IPN-virus in acutely stressed fish over serum from non-stressed fish. However, these results are too few for final conclusion. If at all true, increased serum protection in stressed fish may however not be the only or even the major mechanism to explain the phenomenon. An extensive literature study has been conducted and yielded several other possible mechanisms of action, which are described and suggestions for further research presented. Project status: Liðug << Back |
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