Research news 2012

N I F E S e x a m i n e s t h e s e a f o o d y o u e a tRESEARCH NEWS

2012

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Dear reader,

NIFES does research on the seafood that youeat, or ought be eating.

Both Norwegian and international healthauthorities confirm that food from the seashould form part of a healthy balanced diet.Fish contain nutrients that are essential to thewellbeing of all of us and are a key aspect ofpublic health at a time when obesity anddiabetes are a serious world-wide problem.

We know that seafood is an important sourceof protein. We know that vitamin D plays adecisive role in promoting bone health. Weknow that omega-3 marine fats, which aremostly found in oily fish, but also to a certainextent in lean fish, help to preventcardiovascular disease. And we also knowthat many of these nutrients have severalother positive effects on body and soul;effects that need to be further studied so thatwe can document them accurately andreliably.

This is why NIFES exists; because we needmore research on what seafood does to usand what it can do for us.

However, if we wish to understand how fishaffects us, it is not sufficient to study whatlies on our plates. We also need to study howseafood is produced under ever-changingenvironmental and nutritional conditions.NIFES is involved in the cultivation ofwrasse, a species of fish that eats salmon liceand thus can provide an environmentallyfriendly solution to the problem of liceinfestations. NIFES does research on howclimate change and rising sea temperaturesaffect farmed salmon. This field of researchmay well turn out to be decisive for our veryability to maintain an aquaculture industry inthe future. NIFES is also involved indocumenting the effects of oil-spills on codlarvae, as one aspect of assessing the risksinvolved in potential petroleum-relatedactivities off Lofoten and Vesterålen. Large-scale monitoring programmes bring NIFESdata that enable us to document the contentof nutrients and undesirable substances inseafood from the open sea, fjords and fishfarms.

One of the major questions in research onseafood turns on how farmed fish can tacklethe growing use of vegetable matter in fish

feed. The limits of available resources offish-oil and fish-meal have long since beenreached, and these will have to be replacedby fat and protein from other sources. NIFESis studying how fish health and welfare arebeing affected by these changes, and what ishappening to the nutritional content of ourseafood. The welfare of our fish also affectsour own welfare, which is why NIFESresearch is both wide-ranging and deep-going.NIFES does research on the totality of theseafood you eat. Good reading!

Øyvind LieDirector

Research News from NIFES

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ContentsSustainable development of aquaculture 7

Alternative resources 7

- Genetically modified plants in fish feed 7- Krill meal in fish feed 9- Animal by-products in fish feed 9- Fish by-products 10- Plant ingredients 10

Fish faeces as a fertiliser in agriculture 13

Climate and nutrition 14

- Climate change - consequences for salmon and trout 14

Fish nutrition and fish welfare 16

- Cardiomyopathy syndrome (CMS) in salmon 16- Histidine against cataracts 16- New markers to reveal vitamin and mineral

deficiency in trout 17

- Hungry herring 17- Certain oil components affect the development

of cod larvae 19- Oil contamination of the food chain 19

Aquaculture of other species 20

- Nutrient availability – its significance for the development of cod farming 20

- Skeletal development in cod 21- Spawning problems in cod 22- Wrasse farming: development of a good

feed for growth 22

Design of regulations for safe feed and seafood 25

- Synthetic antioxidants in fish feed; their significance for food safety 25

- Toxaphene in feed and fish 27

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Status of undesirable substances in Norwegian seafood 29

Wild fish from Norwegian maritime areas 29

Monitoring on behalf of the Norwegian Food Safety Authority 36

- Veterinary border inspections of imports 36- Undesirable substances in wild fish from

coastal waters 36- Environmental toxins in fish and fish products 40- Forbidden substances, medicines and

contaminated substances in aquaculture 41- Salmon louse drugs in lobster and farmed salmon 42- Monitoring of feed and feed ingredients

for farmed fish 42- Monitoring parasites 44

Shellfish and crustaceans 47

- Research on mussel 48

Monitoring of shipwrecks and sunken vessels 49

- Monitoring submarine U-864 near Fedje 49

Management plans 51

- Long-term monitoring 51

Interactions between undesirablesubstances and nutrients 53

- Selenium counteracts the effects of mercury 53- Omega-3 and methyl mercury 54

Seafood in our diet and its implications for our health 57

Obesity and diabetes 58

- Significance of principal nutrients in the diet 59- Significance of undesirable substances in the diet 60- Relationship between omega-6

and vegetable fat 62

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Mental health 64

- Can seafood affect behaviour? 64- Can seafood help overcome postnatal depression? 65

Spine and bone health 66

- Effects of marine oils on back pain 66- Vitamin D from salmon - just as effective

as dietary supplements 66

Effects of omega-3 on health 67

- Does the source of omega-3 influence its uptake? 67- Whale oil as a source of omega-3 68- Lean fish are a source of omega-3 69- Fish-milt and its effects on health markers 70

Seafood in an whole food chainproduction perspective 71

NIFES is a national reference laboratory 73

Aquaculture Nutrition 74

Teaching and training 75

Teaching at the University of Bergen 75

Contents

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Prognoses suggest that by 2030,similar amounts of seafood will beproduced by aquaculture as byfisheries. Obtaining sufficient feedresources will therefore posesignificant challenges. Today,commercial fish feed may containas much as 50 percent plant oilsand 50 percent plant proteins asalternatives to marine ingredients.

Alternative ingredients include plantoil, plant meal, genetically modifiedplant raw materials and krill meal.Major changes in the mixture ofingredients used to make up feed,such as a higher proportion ofplant materials, call for increasedknowledge how to balancenutrients in the feed in order toensure fish health and welfare, andto ensure a sustainabledevelopment of the aquaculturesector..

Alternative resources

Genetically modified plantsin fish feed

Maize is used as an ingredient in fish feed.Today, a large proportion of the maize andother plants available on the market aregenetically modified (GM) products, allowedto be used in fish feed. Salmon feeding trialshave been performed with GM maize andGM-soybean. Effects were studied by meansof a number of fish health indicators. Theresults revealed no negative effects of GMsoybean, while the GM maize trials were lessclear. Attempts have been made to evaluatewhether other factors, such as contaminationof the maize by mycotoxins (from fungi),might have caused these results.

GM maize and fish health Due to high costs of feeding trials with

Sustainable development of aquaculture

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«Today, commercial fish feed may contain as muchas 50 percent plant oils and 50 percent plantproteins as alternatives to marine ingredients»

salmon, long-term trials have been performedby means of Zebrafish. Several generationsZebrafish were fed GM maize, their growth,gut health, blood health and genes expressionwere studied. Reproduction, markers in eggsand larvae quality were investigated.

The results showed that Zebrafish fed normal(non-GM) maize grew more slowly than fishgiven GM maize. The effects on growth didnot appear until the second generation. Thereduction in growth may be explained bydifferences in mycotoxin content in GM andnon-GM maize. It is important to realise thatfish may respond to other factors (such asmycotoxins) than the genetic modificationitself. No effects were found on reproduction.So far, these results suggest that GM maize isas safe for zebrafish as non-GM maize, evenwhen fed for several generations.

Financial support: Ministry of Fisheriesand Coastal Affairs.

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Krill meal in fish feed

Krill is one of several alternative feedresources. Krill meal is a good source ofprotein and marine fatty acids, but it alsocontains natural high levels of fluorine.Trials using Atlantic salmon, Atlantic halibutand Atlantic cod in seawater have shown thatthe fluorine in krill meal is not taken up bythese fish. Irrespective of species and thelevel of fluorine in the feed, there were noincreases in fluorine concentrations ofmuscle, bone, gills, kidneys or scales/skin.

Freshwater trials with trout showed thatfluorine from fish meal can be taken up andstored in bone. We therefore investigated ifthe salt in seawater affected uptake andaccumulation of fluorine from krill meal inAtlantic salmon. The experimentsdemonstrated that this is not the case; it spiteof its high fluorine content, krill meal can beused to produce feed for salmon in bothseawater and freshwater.

Financial support: Research Council ofNorway.

Animal by-products in fishfeed

Land animal production produces largeamounts of animal by-products (ABP).Exploiting these would help the aquaculturesector to become more sustainable. Wetherefore investigated to which extent variousABPs could function as substitutes for fishmeal and fish oil in feed for Atlantic salmon.

A number of by-products from poultry andpork were included in salmon feed in anexperiment that aimed to find how ABPsaffected fish growth and health. Three typesof feed were studied, in which either protein,fat or a combination of the two were replacedby ABPs. The salmon displayed few signs ofwelfare problems such as sores, deformitiesor cataracts. All groups grew at the same

rate. The groups that had been fed the highestproportion of ABPs in the protein fractionshowed reduced feed utilization. Furtheranalyses of the data from this experimentmay reveal differences in nutrientmetabolism, hormonal control, the immunesystem and gut health.

The use of animal by-products as feedingredients does not include products fromruminants (cattle), due to the risk of infectionwith bovine spongiform encephalitis (BSE)or “mad cow disease”. This makes itessential to be able to identify any illegalinclusion of material from cattle in feed andfeed ingredients. We are currently developingmethods to reveal such inclusions.

Collaboration: Nofima (Norway and AVSChile), EWOS Innovation (Norway andChile), EFPRA (European Fat Processors andRenderers Association).Financial support: Research Council ofNorway.

Fish by-products

As a step towards the development of asustainable fish-farming industry, we havecarried out trials involving the utilisation ofphosphorous and protein from acid-treatedfish-bones in salmon feed. The resultsdemonstrated that phosphorous from bonehydrolysate can be utilized by salmon in thesea. Bone hydrolysate is a source ofminerals. Further studies of salmon infreshwater will be performed to determinewhether bone hydrolysate can replace evenmore of the phosphorous in feed.

Collaboration: Nofima.Financial support: Norwegian SeafoodResearch Fund.

Plant ingredients

The inclusion of fish-meal and fish-oil infeed for farmed salmon has fallensignificantly during the last ten years, due torising prices and limited availability.Growing pressure to reduce the use of marineingredients in fish feed means that it isimportant to be aware of the effects of such

alternative fish feed ingredients.

Plant ingredients in salmon feedTrials with Atlantic salmon have shown thatit is possible to use feed for farmed salmonwith a low content of fish oil and fish mealwithout reduction in growth and feedutilisation. In one study, salmon were feddiets in which 70% of the fish meal was

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replaced with plant protein. Either 100% or80 % of the fishoil was replaced with oliveoil, rapeseed (canola) oil or soybean oil. Fishthat were given feed containing soybean oilingested slightly less feed and their finalweight was lower than those fed fish-oil.They also had a reduced feed utilisation andpoorer fat digestion.

Due to the low content of fish-oil and fish-meal, only 0.8 kg of wild fish was needed toproduce 1 kg farmed salmon in thisexperiment. It is thus quite possible to usefeed for farmed salmon that is so low inmarine raw materials that we end up with anet production of marine protein, withoutloss of growth or feed utilisation.

Collaboration: Skretting.Financial support: Research Council ofNorway.

Zebrafish as a model to studyvitamin requirementsPlant ingredients have a different vitamincontent than fish meal and fish oil. E.g. hasfish-meal has a high content of vitamin B12,which is absent in plant meals. NIFES hasstudied whether Zebrafish can be used as amodel in studies of vitamin B12 deficiencyand requirement in fish.

Vitamin B12 in fish can lead to reducedgrowth and anaemia, and a serious deficiencymay result in irreparable damage to thenervous system. Gene expression studiesperformed by NIFES have shown how fishabsorb and transport vitamin B12 in the

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body. This means that Zebrafish can be usedas a model for vitamin B12 studies in fish.

Two groups of Zebrafish were given twodifferent feeds that contained either a smallor a large proportion of vitamin B12. Thefeed that contained a large amount of thevitamin had about as much of it as fishmeal,while the low-content feed contained justabove minimum vitamin B12 requirementsdescribed for other fish species.

The results showed no differences betweenthe two diet groups in terms of neithergrowth nor anaemia. However, the low-vitamin B12 feed was not sufficient tomaintain the fishes’ own store of thisvitamin. The Zebrafish’s vitamin B12requirements are probably greater than thosethat have previously been described for fish.


Amino acid requirements of salmonPrevious studies have shown that bothdeficiencies and imbalances in specificamino acids in fish feed affect salmon growthand health. Alternative protein ingredients forfeed contain different concentrations ofamino acids compared to fish-meal. In orderto understand how future fish feeds should beproduced, it is essential to be aware of theconsequences of an imbalance in essentialamino acids. It is also important tounderstand the consequences for health of anamino acid imbalance in order to be able toproduce good fish-feeds with the ingredientsthat will be available in future.

NIFES has carried out two experiments onyoung salmon, based on feed that containedonly small amounts of fish-meal and a greatdeal of plant-based sources of protein. In oneexperiment, the fish were given feeds withdifferent amounts of the amino acids lysineand arginine. Another experiment looked at

how growth and metabolism are affectedwhen methionine is present in the feed ineither low or sufficient amounts.

The results showed that insufficientmethionine reduced growth, while therelative proportions of lysine and argininehad no effects on growth in salmon.Metabolic effects were observed in bothexperiments, but more analyses will beneeded before final conclusions can bedrawn.

Collaboration: EWOS, Nofima, Universityof Bergen. Financial support: EWOS Innovation andResearch Council of Norway.

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Fish faeces as afertiliser in agriculture Aquaculture produces large amounts offaeces, which end up in the localenvironment and are a potential source ofpollution. If faeces could be pumped up andutilised as agricultural fertiliser, it would giveus a source of phosphorus simultaneously aspollution below sea-cages is reduced.

NIFES participated in a pilot project thataimed to find if faeces could be utilised as afertiliser in agriculture. For salmon faeces tobe a potential fertiliser, it must have a lowcontent of heavy metals, and contain positivecomponents of fertilisers, such asphosphorus, nitrogen and potassium insufficient concentrations. NIFES’ task in thestudy was to measure heavy metals, positive

nutrients such as potassium and phosphorus,and the nitrogen content of collected faeces.The crop plants were also analysed afterbeing dosed with fertiliser in order to seewhether they had taken up heavy metals.

Salmon faeces did not contain heavy metals,and their nutrient content was positive. Theplants fertilised with faeces grew well. theheavy metals in plants fertilised with fishfaeces were in the same range as cucumbersfertilised with an all-in-one fertiliser. Faecescollected from sea-cages is therefore apotential source of fertiliser for agriculture.Financial support has been sought tocontinue this project

Collaboration: Bioforsk, Linga Laks, LiftUp.Financial support: Regional ResearchFund; Western region.

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Climate and nutrition Climate change is affecting the environment,and may lead to changes in sea temperatureand pH. Statistics show that Norwegiancoastal sea temperatures are rising. This mayhave implications for salmon, which are mostcomfortable below about 15 – 17 degreesCelsius. NIFES is studying how changes insea temperature affects salmon and trout.The studies are carried out in collaborationwith the Institute of Marine Research atMatre Aquaculture Research Station, wherewater temperature can be monitored.

Climate change -consequences for salmonand trout

NIFES has studied how well salmon and

trout withstand changes in temperature, byfollowing fish through a temperature stress(short duration) that involves a rapid rise intemperature. Further long-term effects wereinvestigated after long-term temperatureexposure. The studies aim to find how fishregulate genes and switch them on and off inorder to protect themselves against short- andlong-term episodes of high watertemperature. The results will help to identifya feed formula with which salmon and troutare comfortable, and which enables them togrow and optimally utilise their feed atelevated sea temperatures. A further goal is toidentify nutrients which need to be present inthe feed to maintain good fish health. Thisknowledge will be important to ensure thataquaculture can develop in a sustainabledirection in future. So far, the results haveshown that there are considerable differencesbetween salmon and trout in how theyregulate growth and nutrient metabolism at

elevated temperatures, and how sensitivethey are to the development of tissueoxidation and eye cataracts. In this respect,trout appear to be more robust than salmon.

NIFES has investigated whether there arechanges in micro- and macronutrientrequirements of salmon when temperaturesrise, and whether potential feed additivescould alleviate changes in growth and thedevelopment of production related diseases.The aim was to develop a feed that wouldoptimise the ability of the fish to deal withtemperature change.

Consequences for salmon growthStudies have shown that the hunger-regulating hormone ghrelin is suppressed insalmon at high temperatures. This means thatstimuli from this signalling agent in thebrain, which regulates appetite and food

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consumption, are weakened. Salmon that livein water at 19 °C reduce their food intake by50% relative to fish living at 14 °C, and theirgrowth is thus correspondingly poorer.

It also turned out that the fish that reducedtheir consumption used own fat reserves,particularly those of omega-3 fatty acids.High temperatures thus had consequences notonly for growth but could also lead tochanges in the composition of nutrients inthese fish.

Collaboration: Institute of MarineResearch, Marine Harvest, Nofima,Skretting ARC.Financial support: Research Council ofNorway, Ministry of Fisheries and CoastalAffairs.

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Fish nutrition and fish welfare

Cardiomyopathy syndrome(CMS) in salmon

Cardiomyopathy syndrome (CMS), a diseaseof the heart, leads to the death of fish and is agrowing problem in adult farmed salmon. Ithas already been shown that CMS is causedby a viral infection, and that it is highlyinfectious. A major research project thatbrings together many participants fromresearch and industry has been launched tostudy various aspects of this cardiacsyndrome.

It has previously been demonstrated that fishcan carry the virus without becoming illthemselves, and that individual sea-cages canhouse both sick and healthy individuals.There are several possible reasons for this,

and the project will investigate, among otheraspects, whether temperature, feedcomposition, environmental factors orparticular stages in the life cycle make fishcarrying the virus more liable to develop thedisease.

NIFES is contributing to the project bymapping the development of the disease inheart muscle, and by investigating the roleplayed by nutrition. Interim results show thatthe amino acid histidine in the heart is linkedto the development of this disease, and thatthe amount of histidine in the heart reflectsthe level in the feed. We will also studywhether histidine in feed lowers theincidence of the disease in large salmon.

Collaboration: Marine Harvest, Institute ofVeterinary Science, Norwegian Veterinary.University, Nofima Marin, Pharmaq,AquaGen, Lerøy Seafood Group, Ewos.

Financial support: Research Council ofNorway, Norwegian Seafood ResearchFund, Ministry of Fisheries and CoastalAffairs.

Histidine against cataracts

In salmon, cataracts are the result of poornutrition, and has been related to histidineand plant ingredients in fish feed. A numberof recent studies have shown that the sourcesof fat in the feed do not affect cataractdevelopment. On the other hand, the resultsdo demonstrate that salmon smolt have agreater need for histidine to hinder cataractdevelopment than was previously supposed.This confirms the importance of histidinesupplements or using histidine-rich feedingredients (e.g. animal by-products such asblood meal) to hinder cataract development.The work that remains to be done in thisproject may help to clarify why histidinerequirements are twice as high as they wereten years ago.

Collaboration: Marine Harvest, SkrettingARC.Financial support: Marine Harvest,Skretting ARC, Ministry of Fisheries andCoastal Affairs.

New markers to revealvitamin and mineraldeficiency in trout

NIFES has previously performedexperiments with increased levels of vitaminand mineral supplements in a modern plant-based feed for rainbow trout. The studyshowed that fish not given the supplementsuffered from poor growth rates and reducedhealth status.

We have studied which mechanisms areaffected in the liver of rainbow trout withmicronutrient deficiency. Both vitamins andminerals affected various aspects of the fish’metabolism. A new tool has enabled us to

identify which vitamins and minerals thateither reinforced or reduced the effects. Thetool developed has been made available indatabases, and will be used in a recentlylaunched European Union project.

Collaboration: Biomar.Financial support: Biomar, Ministry ofFisheries and Coastal Affairs.

Hungry herring

Scientists at the Institute of Marine Researchhave noted that Norwegian spring-spawningherring (NSSH) have become thinner in thepast few years. There has also been a fall inthe amount of plankton on the herring’sfeeding grounds. NIFES has analysedNorwegian spring-spawning herring, and theresults reinforce the observations of thinherring and a lack of nutritional resources.

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Dry matter, fat and protein in whole fish andherring fillets were analysed, as waspreviously done in 1994 and 1997. Theresults obtained from the herring in autumn2011 showed that the herring had a low fatcontent, similar to that of 1997, which was apoor year, while it was lower than in 1994,which seemed to have been a good year.

There also seems to be relationships betweenthe nutritional content of whole fish andfillets, between fat and protein content andbetween nutritional content, condition andsexual maturation. The results will beavailable in the course of 2012.

Collaboration: Institute of MarineResearch.Financial support: Ministry of Fisheriesand Coastal Affairs.

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Certain oil componentsaffect the development ofcod larvae

A number of problems are related to how oil-spills affect fish in the sea. NIFES hasstudied how oil components affect bonedevelopment in cod.When cod larvae were exposed to oil, theformation of the skeleton was affected.Genes that build bone were down-regulated,especially by water-soluble oil components,while genes for enzymes that break downbone were up-regulated. Oil components canaffect cod larvae via changes in bonemetabolism that weaken the skeleton. Theycan also modify the cod’s detoxificationmechanisms, i.e. systems to get rid ofpoisons in the body. Oil components can alsoaffect cell division processes and lead to celldeath.Cod larvae that has to swim in areas wherethere are oil-spills (whether these are

controlled or uncontrolled) may have reducedability to survive and grow to adulthood.There are narrow margins between win orloose in a cod larvae life, and water-solublecomponents from oil spill clearly make anegative contribution to the balance.

Collaboration: SINTEF, NTNU, BioTrix.Financial support: Statoil ASA, ResearchCouncil of Norway.

Oil contamination of thefood chain

In order to support risk assessments of oil-related activity in the Arctic, the Institute ofMarine Research performed feeding trials onherring, which were given feed based on oil-contaminated krill. NIFES demonstratedmetabolic effects on the herring, measured aschanges in the liver. These changes may berelated to the herring’s health, stress,temperature regulation and cell membrane

stability. Herring contain the enzymethiaminase, which has been linked to theM74 syndrome, a reproductive disorder thatcan result in high rates of mortality in salmonfry. In an attempt to elucidate therelationship between oil contamination andthiaminase, the enzyme was analysed in theexperiments. The results showed thatthiaminase is related to the herring’s immunesystem, which is generally inhibited by oilpollution.

Collaboration: Institute of MarineResearch.Financial support: Ministry of Fisheriesand Coastal Affairs.

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Aquaculture of otherspecies Feed composition is a decisive factor in thenormal development of farmed fish that arehealthy and safe to eat. NIFES is studyingthe nutritional requirements of fish and theeffects of nutrients and other substances infeed on fish health, welfare and development.The Institute is studying how nutrition canensure the predictable production of viablefry, prevent deformities and improvement ofbroodstock fish.

Nutrient availability – itssignificance for thedevelopment of cod farming

The composition of nutrients in feed isimportant for the ability of cod larvae togrow and develop normally, for examplewithout skeletal deformities. NIFES isstudying the importance of nutrientcomposition in cod larvae feed, for growthand development.

Unlike in salmon fry, the cod larvae gut isnot sufficiently well developed to enabledigestion dry feed. In nature, cod larvae eatcopepods but these are difficult to cultivate inthe laboratory. In aquaculture, therefore, thelarvae are dependent on being fed rotifers, aquite different type of live feed. Rotiferscontain smaller amounts of minerals thancopepods.

We know that fish larvae have a limitedability to digest protein, and that fat digestion

in cod larvae is not fully developed. NIFEShas previously studied the development ofthe ability of the cod larva to digest fat, andhas found that from day 40 onwards, itsability to utilise fat is good.

Enrichment diet for cod larvaeOur general knowledge of mineral, fat andprotein requirements for fish was used byNIFES to developed an optimised enrichmentdiet for cod larvae. This diet includesprotein, various amino acids, phospholipids,iodine, selenium, manganese, copper andzinc. The diet has been tested in both small-and large-scale feeding trials.

NIFES has also studied how the iodinecontent of feed affected the development andgrowth of cod larvae. Both insufficient andexcess iodine have negative effects. Thestudy found that excessively highconcentrations of iodine were toxic to codlarvae. The optimal range for iodine arebetween 1 and 20 mg/kg. So far, we have not

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established any selenium requirements forcod larvae.The results of the project show that it will bepossible to improve enrichment diets forrotifers used when raising marine fish larvae.

Collaboration: Nofima, Skretting ARC,Havlandet Marin Yngel, CCN, SagafjordSea Farm.Financial support: Research Council ofNorway.

Skeletal development in cod

Industrial production of cod larvae usesrotifers for start-feeding. These are enrichedwith nutrients that improve their ability tohelp cod larvae to survive and grow. Untilnow, there have been various opinions abouthow much vitamin A should be added to theenrichment diet. It turns out that this dependson the composition of the fatty acids in thediet. Adding little or no vitamin A is the leastrisky option.

Cod larvae fed different amounts of vitaminA and the fatty acid arachidonic acid (ARA)were studied. We studied gene expressionand looked at the results of a microarray, amethod that allows all of a cod’s genes to beexamined simultaneously.

Initially the project emphasized that vitaminA and ARA in conjunction would affect thedevelopment and growth of the skeleton incod larvae. However, chemical andanatomical analyses of the cod larvaerevealed that ARA has the most seriousnegative effect on skeletal development.Enhanced amounts of ARA in the feed led tochanges in vitamin A metabolism, whichseemed to balance regulation of cell divisionand cell death. Increasing the content ofvitamin A gives cod larvae even poorer bonedevelopment, but only as long as the contentof ARA is high. At low levels of ARA, nosignificant changes occur as a result ofadding extra vitamin A.

The expression of a surprisingly largenumber of genes was affected by smallchanges in the composition of the feed, asituation that led to major changes in themetabolism and weight regulation of thelarvae. It remains to be determined whethersuch changes are heritable or will return tonormal values when cod are given a differentand better feed.

Collaboration: Radboud University,Nijmegen, The Netherlands, St. LawrenceUniversity, USA, NRC, Canada, CCMAR,University of Algarve, Portugal.Financial support: AquacultureProgramme’s TOPPforsk, European Union’s7th Framework Programme, Ministry ofFisheries and Coastal Affairs.

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Spawning problems in cod

Cod that grow up in captivity often haveproblems with their spawning rhythm. Codare batch spawners that spawn every two tofive days over a period of several weeks.Cultivated cod often suffer from spawningproblems, when batches of mature eggs arenot released, but accumulate in the gonads.This means poor egg quality, and often leadsto the death of the fish unless the eggs arestripped. NIFES has studied spawningproblems in cod in order to discover itscauses.

Cod in sea-cages were fed after first sexualmaturation and for a year thereafter with ahigh-fat (20%) or low-fat (13%) diet, wherethe fat replaced carbohydrates. Some of thefish were then moved to a tank on shore.Each of the two groups was divided into twosub-groups, one of which was subjected tostress by lowering the water level anddrawing a hand net through the tank for ashort time once a week.

The interim results show a weak positiveeffect of high fat content and a negativeeffect of stress on spawning success andspawning problems in the fish. NIFES is alsoinvolved in a project that aims to understandwhat happens during egg maturation.

More studies are needed to answer thequestion of how to avoid spawning problemsin cultivated cod broodstock.

Collaboration: Institute of MarineResearch, Skretting ARC.Financial support: Research Council ofNorway, Ministry of Fisheries and CoastalAffairs.

Wrasse farming:development of a good feedfor growth

Wrasse, a fish species of the labrid family,can be an environmentally friendlyalternative in combatting salmon lice.

However, cultivated wrasse will not grow ontraditional aquaculture feeds. Wrasse have arather special gut, which among otherpeculiarities lacks a stomach, which meansthat their digestion and uptake of nutrientsare somewhat unusual. If we manage todevelop a feed that the wrasse digestivesystem can deal with, we will be able toreduce the consumption of medicines inaquaculture. This would also protect wildstocks of wrasse, which are currently fishedto be used in fighting salmon lice.

In a collaborative project with Nofima,NIFES will study all aspects of wrasseaquaculture. Among other tasks, NIFES willfind how feed ingredients and feedingregimes can be adapted to the peculiarbiology of the wrasse. One challenge hasbeen to develop a good grower feed for thefry. The fry that are produced suffer fromseveral deformities and fin wear, both ofwhich conditions can be improved by correctnutrition.

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Nutrient composition The principal hypothesis is that wrassefunction similarly to cod larvae as far as theingestion, digestion and absorption ofnutrients are concerned. Studies have shownthat the feed ought to contain 12 – 20 percentcarbohydrates and less than 18 percent fat,with the remainder being protein. Shrimpmeal is a decisive factor in ensuring thatwrasse eat and grow on dry feed. In order tohave several alternative ingredient sources toensure that the feed is eaten, we are workingon identifying a replacement for shrimp mealin wrasse feeds.

Prawn meal has been replaced by prawn shell

meal, mussels, krill and squid. Thesedifferent kinds of feed appeared to lead topoorer growth and higher mortality thanshrimp meal. Among the reasons for this maybe that the fish used in the trials hadpreviously been fed a shrimp containing diet.For this reason, we have now studied fishthat had been habituated to another type offeed, and the results are currently beinganalysed.

NIFES has analysed the composition ofnutrients in rotifers from various commercialsources, and has identified both obviousnutritional deficiencies and toxic levels ofcertain nutrients, which could explain why

wrasse fry suffer from deformities. In orderto check that broodstock have a well-balanced nutritional intake, the nutrientprofile of the roe of wild and farmedbroodstock will be compared. Fry have beenfed various types of nutrients in order todetermine whether they can stimulatenutrient uptake; for example, the addition ofa special type of fat to the feed produced a40 percent rise in growth rate. These studiesare continuing in 2012.

Several challenges remain before we achieveenvironmentally friendly, sustainablecultivation on a large scale, but rapidprogress is being made. The first majorchallenge will be to identify the most suitablefeed.

Collaboration: Nofima, Institute of MarineResearch, Villa Miljølaks, Marine Harvest.Financial support: Norwegian SeafoodResearch Fund.

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Design of regulations for safe feed and seafood

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Food safety is attracting a growingamount of national andinternational attention, and a goalis to draw up regulationsconcerning the presence ofundesirable substances in fish feedand seafood. Science-basedknowledge about undesirablesubstances in seafood and abouttheir effects is a prerequisite forregulatory changes. Differentundesirable substances havedifferent properties, and problemsconcerning environmental toxinsand feed and raw materialadditives are important aspects offood safety research. Some of theundesirable substances that arefound in feed can absorbed and

retained by fish, and thus affectfood safety. More knowledge ofsuch substances is needed toenable the authorities to provide thegeneral public with advice aboutseafood consumption. Anunderstanding of how undesirablesubstances are transferred “fromfeed to fillet” forms part of the basisof the science-based riskassessments carried out by theScientific Committee on FoodSafety (VKM) in Norway and theEU’s European Food SafetyAuthority (EFSA). Risk assessmentsform the basis of the EuropeanUnion’s food safety upper limitvalues, which are set by theEuropean Commission.

Synthetic antioxidants infish feed; their significancefor food safety

Antioxidants are used as preservatives inboth feed and foodstuffs. In our food,antioxidants delay the onset of rancidity,while in our bodies, they protect us againstcell damage caused by oxidation. There aremany types of natural and syntheticantioxidants; for example, vitamin E andvitamin C are natural antioxidants.

Synthetic antioxidants are classified asadditives, and in Norway and the EuropeanUnion five types are permitted for use in fishfeed; BHA, BHT, EQ, PG and OG. Theseprevent the fat in the feed from becomingrancid. EQ (ethoxyquin) is a syntheticantioxidant that is in a special position vis-à-vis the other four. It is compulsory to add it

to fish-meal that is to be transported by boat,because it prevents heat generation andspontaneous combustion. Because it cancause liver and kidney damage in animals,the amount that can be added is subject tostrict regulation. It is forbidden to add EQ tofood.

The European Union’s upper limit for thesum of BHA, BHT and EQ in feed is 150mg/kg. Figures obtained from monitoringfeed and feed ingredients show that thecontent of these antioxidants in Norwegianfish feed lies below this value.

Research done by NIFES has shown thatBHA, BHT and EQ are carried over tosalmon muscle, and that consumption of 150g of salmon provides 7.5% of the acceptabledaily intake (ADI) of EQ, 0.035% of the ADIof BHA and as much as 37% of the ADI ofBHT.

Interaction among antioxidants –reduced or reinforced effects?NIFES has studied the effects of syntheticantioxidants on cell survival and geneexpression, using liver cells from zebrafish,salmon and human beings. Since thesubstance usually occurs as an mixture infood, NIFES has looked at the effects ofinteractions among them.

Our experiments have shown that individualantioxidants can either reduce or potentiateeach other’s effects. EQ is usuallytransformed into EQDM in fish fillets.EQDM is not covered by current regulations,but is expected to be incorporated as part ofa total limiting value for EQ (EQ + EQDM)in future. If that is the case, the combinedconcentration of EQ and EQDM couldexceed the current upper limit for thesynthetic antioxidants.

A number of metabolic products of EQ, BHTand BHA have been identified, and their

toxicity has been tested in severalexperiments. Rats were given feed to which2500 times as much synthetic EQDM as theacceptable daily intake had been added. Nonegative effects on growth, or signs ofdiscomfort, were observed, which means thatrats can tolerate relatively high doses ofEQDM. It is important to find other researchmodels in order to reduce the number ofanimals used in animal experiments,therefore cell studies. Knowledge derivedfrom these studies will form part of thescientific foundations of the European FoodSafety Agency’s (EFSA) re-evaluation offeed additives, which will also include a riskassessment of metabolic products.

Collaboration: University of Bergen,NTNU, University of Applied Science,Switzerland.Financial support: Research Council ofNorway, Ministry of Fisheries and CoastalAffairs, Norwegian Seafood ResearchFund.

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Toxaphene in feed and fish

In the 1970s, toxaphene was among the mostwidely used insecticides, but it has sincebeen phased out in most countries. Long-distance transport in the atmosphere and bymarine currents has carried toxaphene toarctic regions, where it is primarilyencountered in the marine environment. Thissubstance is a complex mixture of a largenumber of related compounds, many ofwhich degrade slowly and are fat-soluble,which means that they bioaccumulate in fattytissue. Environmental contamination bytoxaphene is usually due to one of threeforms (CHB3), and these are normallymeasured in environmental samples, as wellas in foodstuffs. Other forms (CHB4) alsoexist in the environment, but we lackknowledge regarding the levels and toxicityof these compounds. The European Unionhas set an upper limit for the three mainforms of toxaphene, and recommendsmonitoring a further four forms that occur in

fish products. Most studies of the toxicityand metabolism of toxaphene have been ofexposure in water, to which fish are moresensitive. More knowledge is also neededabout the effects of exposure via feed.

NIFES has studied the uptake, metabolismand excretion of various forms of toxaphenefrom feed in zebrafish and salmon. Theresults show that forms of toxaphene areconverted to compounds with fewer chlorineatoms, which accumulate in fish fillets.Toxaphene in salmon feed reduced growthand the ability to produce a thyroid glandhormone that is important in metabolism. Afall in toxaphene levels in fish can be

interpreted as a result of reduced exposure totoxaphene. However, this could be becausetoxaphene is converted to forms that containless chlorine, which is not detected bystandard analyses.

The knowledge obtained via this study willbe important for future risk assessments oftoxaphene in feed, and how it is transferredto fish.

Collaboration: University of Plymouth,University of Radboud, Nijmegen.Financial support: Research Council ofNorway, Ministry of Fisheries and CoastalAffairs.

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The seafood that we eat must besafe. Every year, NIFES carries outa range of programmes thatmonitor the content of undesirablesubstances in fish, fish products andfish feed. In order to be able toperform risk assessments and tocontinue monitoring in the future, itis necessary to possess a correctpicture of undesirable substances inwild fish from Norwegian waterstoday. Recent knowledge showsthat today’s wild fish monitoringregime is less than adequate.

For this reason, NIFES is currentlyperforming thorough surveys of thecontent of undesirable substances infish from Norwegian waters; theseare known as baselineinvestigations. NIFES also monitorsrandom samples and runs amonitoring programme for theNorwegian Food Safety Authority.

Wild fish from Norwegianmaritime areas

The baseline investigations involvesystematic surveys of undesirable substancesin fish stocks that are fished. These alsoinclude potential seasonal variations in thecontent of undesirable substances. A basicsurvey of the current situation in wild fishfrom Norwegian seas is a prerequisite forfuture risk assessments of seafoods, and isessential for the design of future monitoringprogrammes. The lack of credibledocumentation of undesirable substances haspreviously led to restrictions on the import ofNorwegian fish.To date, the Institute has performed baselineinvestigations of NSS herring, Greenlandhalibut and mackerel. Similar studies ofsaithe, cod and North Sea herring are wellunder way. Greenland halibut and NSSherring are now subject to new monitoringsystems based on the baseline investigations.

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Status of undesirable substances in Norwegian seafood

«A basic survey of the current situation in wild fish fromNorwegian seas is a prerequisite for future riskassessments of seafood, and is essential for the design offuture monitoring programmes»

SaitheSaithe is an important species for Norwegianfisheries, with annual catches amounting tosome 200 000 tonnes. There are two stocksin Norwegian waters; North Sea saithe (southof 62 °N) and North-east Arctic saithe (northof 62 °N). North-east Arctic saithe is thelargest and most important stock as far theNorwegian fishery is concerned, with anannual catch of 140 000 tonnes. Beforebaseline investigations of saithe commenced,monitoring activities in Norwegian waterswere extremely limited.

The baseline investigations of saithe arecarried out as two separate studies. Surveysof North-east Arctic saithe started in 2010,while North Sea saithe will be surveyed from2012 onwards. A total of 1000 saithe from 40positions will be collected. The samples willbe analysed for heavy metals such asmercury, cadmium and lead in flesh andliver, and for organic environmental toxinssuch as dioxins, dioxin-like PCBs, non-

dioxin-like PCBs and brominated flameretardants in liver.

Tentative results indicate that levels of heavymetals in flesh are generally low, while levelsof dioxins and dioxin-like PCBs may be highin individual fish. This indicates that thelevel of organic environmental toxins ishigher in the North Sea than the Barents Sea.When the final results become available in2012, the data will provide a basis forevaluating the risk situation in saithe north of62 °N.

Financial support: Norwegian SeafoodResearch Fund.

Cod North-east Arctic cod, North Sea cod andcoastal cod are distinct strains of cod thatlive in Norwegian fjords and marine areas.NIFES started baseline investigations of codin 2009, taking samples from the Barents

Sea. Sampling of cod from the North Sea andNorwegian fjords began in 2010. The codhave been analysed for heavy metals in fleshand liver, and for organic environmentaltoxins such as dioxins, dioxin-like PCBs,non-dioxin-like PCBs and brominated flameretardants in liver.

None of the samples from the Barents Sea orNorwegian fjords contained concentrations ofmercury, cadmium or lead that exceeded theupper limits. Organic environmental toxinsaccumulate in the liver of cod and other non-oily fish. The highest levels of dioxins anddioxin-like PCBs were found in cod capturedin fjords and coastal waters. Levels oforganic environmental toxins in cod fromopen water in the North Sea and theSkagerrak may approach the upper permittedlimits set by Norway and the EuropeanUnion. This could be a reason for anxietyregarding food safety. The levels appear to behigher in the Skagerrak than the North Sea.Livers of cod from the North Sea and the

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Barents Sea have a lower content of organicforeign substances, but the levels of dioxinsand dioxin-like PCBs in the livers of codfrom the Barents Sea are a cause of concern.This is particularly the case for fish taken ineastern areas of the Barents Sea.

In the Barents Sea, we identified 11 (eachwith a sample of 25 fish) out of 32 stations atwhich the mean values of the sum of dioxinsand dioxin-like PCBs in cod liver werehigher than the European Union’s upper limitof 20 ng TE/kg wet weight. For fjord andcoastal cod, 17 of 26 stations showed meanvalues that were higher than the EuropeanUnion’s upper limits. The North Sea samplesdisplayed excessively high values in 14 of atotal of 24 stations.


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North Sea herringSurveys of North Sea herring began in 2009,and sampling has now been completed, with1000 herring from 40 different positions thatcover most of the North Sea from the EnglishChannel northwards to the Shetlands andeastwards to the Skagerrak.

The interim results indicate that in general,North Sea herring have low values of allundesirable substances. Concentrations ofmercury and lead in the samples lay belowthe European Union’s upper limits.Concentrations of certain undesirablesubstances lie above previously registeredlevels, though none of the mean values perposition exceed the upper limits.

At none of the North Sea herring stationswere the mean values higher than the upperlimiting values for dioxins and dioxin-likePCBs. The highest concentrations were foundin samples of local spring-spawning herringof Larvik fjord, where some individual fish

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came in over the upper limit. These herringare not defined as North Sea herring,although they are sold as such. Higherconcentrations were found in herring, whichspawns in winter in the English channel, thanin the northerly populations of the stock,which spawn in the autumn. The highestconcentrations were found in the autumnaround the English Channel, where someindividual values lay above the upper limit.

Where cadmium was concerned, the oppositepicture was seen, with higher values beingfound among northern autumn spawners thansouthern winter spawners. The highestconcentrations were found in herring whichhas spawned, thin and particularly elderlyherring west of the Shetlands, where someindividuals presented values around theupper limit.

Full analysis of all the results will give usadequate credible documentation of the foodsafety of North Sea herring. The results will

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also provide a basis for goal-orientedmonitoring of North Sea herring in thefuture, in which certain seasons and areaswill be prioritised.


Greenland halibut in the NorwegianSeaIn the Greenland halibut baselineinvestigation, which was finalised in 2009,high levels of dioxins and dioxin-like PCBswere found in fish captured on the EggaEdge of Lofoten, and in an area north of theTræna Bank. An advisory notice wastherefore issued against fishing for Greenlandhalibut in these areas. The aim of the 2011monitoring programme was to determinewhether there were any changes in the levelof undesirable substances in areas where highlevels had previously been found.

Thirty Greenland halibut were sampled fromeach of five stations on the Egga Edge, fromthe Halten Bank to Vesterålen. The filletsamples were analysed for heavy metals andorganic environmental toxins such as dioxins,dioxin-like PCBs, PCB7 and brominatedflame retardants in liver.

The results showed lower levels ofundesirable substances than had been foundin the 2006 – 2008 baseline investigation. Onthe Egga Edge off Lofoten, low values ofdioxins and dioxin-like PCBs were found;these did not give rise to anxiety as regardsfood safety.

The area to the northwest of the Træna Bankwas closed to fishing in 2011, and samplesfrom the area were not taken during theinvestigation. The results of the baselineinvestigation therefore have to be used as thebasis of the risk assessment. Samples andanalyses from this area will be carried out in2012.


NSS herring in the Norwegian SeaThe baseline investigation of NSS herring,which was completed in 2008, showed thatthe level of organic environmental toxins washighest in spawning fish captured close to thecoast. In 2011, a follow-up of thisinvestigation was initiated, in which samplesof 25 NSS herring were taken at each of twopositions in the Norwegian Sea. The resultsso far show low levels of mercury, cadmiumand lead. The investigation will be finalisedin 2012, and the results will be used as partof the follow-up of the Management Plan forthe Norwegian Sea.


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Monitoring on behalfof the Norwegian FoodSafety Authority

Veterinary borderinspections of imports

Norway is required to perform veterinaryinspections of goods imported into theEU/EEA from third countries. On behalf ofthe Norwegian Food Safety Authority, NIFESparticipates in drawing up plans andinstructions for inspections related toseafood, as well as ingredients and rawmaterials for feed production. TheNorwegian Food Safety Authority isresponsible for sampling and the initialevaluation of the imported goods. NIFES isresponsible for the analyses and scientificevaluations. The aim of the project is tomonitor microbiological and parasite status,residues of medicines and levels ofenvironmental contaminants in samples of

imported goods. The results of the analysesare used to determine the status of theimport, and any deviations are reported to theNorwegian Food Safety Authority.

Samples are selected, among other criteria,on the basis of information available throughthe European Union’s Rapid Alert System forFeed and Food (RASFF), in terms of species,country of origin, whether the goods arederived from aquaculture, method ofpreservation and evaluation of conditions oftransport. The RASFF reports offer anoverview of the findings of the borderinspection throughout the EuropeanUnion/EEZ, and thus provide a good tool forplanning and sampling purposes.

In 2011, several hundred samples wereanalysed for microorganism, parasites,medicaments and other undesirablesubstances. To date, the potentiallypathogenic bacterium Listeriamonocytogenes has been found in a fewsamples, in concentrations below the current

upper permitted limit of 100 bacteria pergram of food. Intestinal nematodes (Anisakissp.) were also identified in a few samples,but so far, all the parasites found have beendead, and were thus not infectious.

No residues of illegal medicines have beenfound, nor have concentrations of legal drugsabove current permitted levels beenidentified. Further analyses remain to beperformed.

Financial support: Norwegian FoodSafety Authority.

Undesirable substances inwild fish from coastalwaters

Undesirable substances in ediblecrabs and whale-meat The background for surveying the content ofundesirable substances in crab-meat is thefinding of high levels of cadmium in crabs

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caught in Salten in the County of Nordland,where the level in crab claw-meat has beenabove European Union and Norwegianpermitted levels, which has led to the issue ofa local advisory. The crab fishery in this areaalso closed when the Swedish foodauthorities found such crabs on the localmarket. A total of 475 crabs from 48positions along the whole coast of Norway,from Hvaler to Vesterålen, will be analysedfor heavy metals and organic environmentaltoxins. To date, NIFES has analysed 15sample of crabs from Salten, four of whichcontained higher levels of cadmium than arepermitted in claw-meat. Samples of brownmeat also contained high concentrations.These analyses will continue in 2012.

Whales occupy a high position in the foodchain, which means that they can accumulatehigh levels of undesirable substances. Datafrom 2002 indicated levels of mercury inwhale-meat that ranged from 0.03 to 0.61mg/kg wet weight. The highest values werefound in whales taken near Jan Mayen and in

the North Sea. These data were based onlimited sample material, and the NorwegianFood Safety Authority therefore wished toinclude whales in the 2011 programme.Around 100 whale-meat samples have beencollected. These have yet to be analysed, andthe results will be reported to the FoodSafety Authority in 2012.

Undesirable substances in fishIn 2010, several species of fish wereanalysed for their content of less familiarundesirable substances, such as inorganicarsenic, brominated flame retardants andperfluorinated alkyls. Although these arehazardous substances, upper limits have notyet been set. The EFSA is currently gatheringdata on a number of undesirable substancesin food, with the aim of setting limits for atolerable weekly intake (PTWI).

The results of the analyses of inorganicarsenic, brominated flame retardants andperfluorinated alkyls in Atlantic halibut,

Greenland halibut, tusk, saithe, herring,mackerel and cod showed that the content ofthese substances was low. The scope of themonitoring programme differs according tothe species involved. For example, 190samples of cod from eight positions havebeen taken, as have 20 samples of halibutfrom north of 69 °N.

Atlantic halibut have also been analysed fordioxins and dioxin-like PCBs, PCB7 andheavy metals. Excessively high levels of thesum of dioxins and dioxin-like PCBs werefound in two out of 20 samples. These levelswere somewhat lower than in previous years.The samples were taken from the belly offish weighing more then 50 kg. The halibutbelly contains a great deal of fat, in whichthese compounds concentrate. No samplesfrom the dorsal muscle displayed excessivelyhigh values.

The European Union’s food inspectorateEFSA bases its regulations on data thatassume a level of 0.03 mg/kg inorganic

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arsenic in fish fillets. The studies performedby our institute show that the content ofinorganic arsenic is only one tenth of thislevel. EFSA’s estimates are therefore far toohigh, at least as far as Norwegian fish areconcerned.


Environmental toxins in fishand fish products

In 2010, the Norwegian Food SafetyAuthority decided to concentrate onsardines, because few data on this species areavailable. In 2011, in addition to completingthis study, we also analysed mercury in tusk,ling and shellfish in the Hardanger Fjord.This was a follow-up of an earlierinvestigation that found high levels ofmercury in tusk from around Steinstø in theHardanger Fjord. These samples have not yetbeen analysed.

Low level of undesirable substancesin sardines and marine oilsThe 2010 report on sardines summarised theresults from 14 samples of fish-oil, seal-oiland krill-oil, which had been purchased fromvarious shops in and around Bergen. Thesamples were analysed for Salmonella,dioxins, PCBs, polybrominated flameretardants, heavy metals, perfluoratedhydrocarbon compounds and fat. Samples oftinned sardines were also purchased in thesame area, in addition to samples of freshsardines caught in the Trondheim Fjord,Sognefjord, Hardanger Fjord, Høgsfjord inRyfylke county, the Oslo Fjord, and seasardines from the North Sea.

The results showed that concentrations ofPCB7 in the oils were similar to previousfindings in samples purchased from varioussources in the Bergen area. The EuropeanUnion has proposed an upper permitted limitfor PCB6 of 200 µg/kg in oil for humanconsumption, from January 1, 2012.

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Concentrations of PCB6 ranged from 0.1 –80 µg/kg. In both tinned and wild-caughtsardines the concentrations of undesirablesubstances mostly lay well below thepermitted limits. Fifteen tins of sardines wereanalysed, while 35 samples of wild-caughtsardines came from catches taken in theTrondheimsfjord, Sognefjord,Hardangerfjord, Høgsfjord in Ryfylkecounty, the Oslofjord, and sea sardines fromthe North Sea. This probably means that theoils that we analysed have been purified.NIFES has recommended to the NorwegianFood Safety Authority that this part of themonitoring programme should be continuedas a permanent programme. The fact that thesardines displayed good results indicates thatthere is no need for special measures as faras this species is concerned. The new dataalso mean that it is easier to estimate intakeof environmental toxins on the basis ofseveral species in the diet.


Forbidden substances,medicines and contaminatedsubstances in aquaculture International regulations (EU Directive96/23) require Norway to monitor the contentof a range of medicines and environmentaltoxins in farmed fish on an annual basis.These regulations apply not only to farmedfish but also to all animals used in foodproduction. The Norwegian Food SafetyAuthority is responsible for monitoring andsampling, while NIFES performs theanalyses and draws up the reports. Thesystem is regularly monitored and audited bythe EFTA monitoring body (ESA).

On behalf of the Norwegian Food SafetyAuthority, NIFES has analysed both legaland illegal medicines and various types ofcontaminated compounds. Samples weretaken from all over the country throughoutthe year, and around 10 percent ofNorwegian fish farms were represented in thematerial.

Low levels of undesirable substancesin 2010The levels of undesirable substances in filletsof farmed fish tend to reflect the feed that thefish are given, and the European Union hasset upper limits for a number of suchsubstances in fish. Samples of farmed fishwere taken for analyses of organic andinorganic undesirable substances, as well asfish feed additives. The number of fish thatwere studied in 2010 ranged from 45 to1585, depending on the substance involved.The results showed that none of thesesubstances exceeded such upper permittedlimits as had been set. The values of theseundesirable substances in farmed fish arefairly similar to those that have been found inwild species; NSS herring and North-eastAtlantic mackerel, although the range andmaximum values are typically lower infarmed fish. The mean levels of theundesirable substances that have beenanalysed in farmed fish have remained stablesince 2003.

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Salmon louse drug found in 2010The fish louse treatment Emamectin benzoateis added to salmon feed. Residues of thisdrug were found in eight of 188 pooledsamples from farmed salmon. Theconcentrations were below the EuropeanUnion’s upper limits for this substance.

Where medications are concerned, currentregulations provide guidelines regarding thenumber of samples that are to be analysed,and the scope of sampling is determined onthe basis of known consumption. In 2010,chloramphenicol, which is not approved foruse on fish, was demonstrated in 1 of 194pooled samples (each pooled sample consistsof tissue from five individual fish). No levelsof residues that exceeded upper limits werefound.

Financial support: Ministry of Fisheriesand Coastal Affairs, Norwegian FoodSafety Authority.

Salmon louse drugs inlobster and farmed salmon

Due to the high level of attention that the useof the salmon louse treatments diflubenzuronand teflubenzuron has attracted, there is aneed for more knowledge about the effects ofthese drugs, not least as regards how theymight affect crustaceans in the vicinity offish farms.

Diflubenzuron and teflubenzuron can affectthe formation of the carapace (chitinsynthesis) in crustaceans. To study the effectsof medicine residues on crustaceans, lobsterswere exposed to teflubenzuron in amountssimilar to those found in medicated feed or infaeces from treated fish. The concentration ofthe drug in the lobster and its effects onsurvival and behaviour were registered.Tentative results show varying concentrationsin lobsters, but some individual values laywell above the current upper permitted limitfor teflubenzuron of 500 ng/kg in seafood forhuman consumption. Malformations have

also been observed in lobsters that wereabout to moult. These experiments are still atan early stage, and it is too early to draw anyconclusions regarding effects on lobsters.

As well as sampling wild fauna, samples offarmed fish have also been gathered. Salmonfrom farms that had previously been treatedwith these substances were analysed forflubenzurones. No measurable residues werefound in any of the samples.


Monitoring of feed and feedingredients for farmed fish

NIFES monitors the content of undesirablesubstances in feed and feed ingredients forfish and other aquatic animals on behalf ofthe Norwegian Food Safety Authority.Monitoring of substances in fish feed andingredients for fish food is necessary in order

to maintain control of the whole productionchain for farmed fish.

Feed needs to provide fish with the nutrientsthey need for good health. However, feed andits raw materials may contain undesirablesubstances that can have negative effects onthe fish itself, and on fish as a source of foodfor human beings or as an environmentalcontaminant. Since farmed fish obtain theirfood from relatively few sources, and thecomposition of nutrients and undesirablesubstances in fish fillets is affected by thefeed they are given, comprehensivemonitoring of fish feed and of fish fillets isnecessary for a good overview of food safety.

This is also important from the perspective ofrisk assessments related to farmed fish.

The feed monitoring programme has been inoperation since the end of the 1990s. Theprogramme focuses substances that mightaffect food safety, and it includes analyses offorbidden feed components, additives,specific bacteria, fungal toxins, certainmedicaments, pesticides, dioxins, PCBs andvarious heavy metals. The area is regulatedvia upper limits for a range of substances.

In 2011, we analysed 25 feed mixtures forsalmon, 11 samples of fishmeal, 10 plantfeed components (largely sources of protein),

10 samples of fish-oil and 10 of plant oil. Allthe analyses will be completed by spring2012.

Feed monitoring activity has been greatlyreduced in scope. In 2006, 790 randomsamples were gathered, since then thenumber of sample has been cut to the currentlevel of 23. Meanwhile, the composition offeeds has become much more complex.Today, public-sector monitoring of feeds isextremely limited in scope.

Financial support: Norwegian Food SafetyAuthority.

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Monitoring parasites Parasites and microbiological statusof pelagic fish Since 2006, NIFES has annually monitoredthe occurrence of parasites and themicrobiological hygiene situation inNorwegian pelagic fish, with most emphasisbeing placed on herring, mackerel and bluewhiting. Monitoring is important for the sakeof food safety and the aesthetic quality offish products. Continuous monitoring is alsoneeded in order to check the occurrence ofparasites and changes in hygienic conditions.

We do not know why pelagic fish carry aheavier bacterial load than farmed fish. Onereason may be that bacteria from the fish’sgut end up in the storage or production water,because the fish evacuate their gut when theyare crowded into the net.

All the analyses in this project are performedon board Norwegian fishing vessels in order

to reflect authentic capture and storageconditions. This ensures that the data arereproducible and can be compared easily. Inthe longer term, such monitoring, particularlywhere parasites are concerned, may also playa part in assessments of anthropogenicenvironmental impacts on pelagic fishspecies.

Collaboration: Pelagic fishing industry(ashore and afloat).Financial support: Norwegian SeafoodResearch Fund, Ministry of Fisheries andCoastal Affairs, Capture for research.

NematodesThis is the collective term for larvae ofparasitic roundworms that are extremelycommon in wild saltwater fish. If we eat fishthat have not been adequately prepared orfrozen, live nematodes in the flesh maytrigger acute sickness, accompanies by

stomach pains, vomiting and diarrhoea. Livenematodes can also cause allergic reactionsin particularly sensitive people. Nematodeallergies are particularly common in Japanand Spain. In the rest of Europe, includingNorway, little is known about the extent ofnematode allergies. It is important thatNorwegian producers and exporters of fishproducts should possess effective toolscapable of controlling the incidence ofnematodes.

NIFES has examined farmed cod from farmsin the Counties of Nordland and Nord-Trøndelag for visible nematodes in their gutand flesh. To date, none have been found.However, small fish were found in thestomachs of several cod, which indicates thatfarmed cod, as well as consuming dry feed,also help themselves to wild fish that findtheir way into the sea-cages. This is apotential vector for nematode infection infarmed cod.

In order to determine whether a fish productcontains nematode fragments that areinvisible to ordinary inspection, NIFES iscurrently establishing a method of identifyingnematode DNA. Norwegian farmed salmonare assumed not to contain nematodes, andthe industry has therefore been giventemporary exemption from freeze-treatmentof its products. The results of the project willform the basis for deciding whether such anexemption will also apply to farmed cod.

Collaboration: Institute of VeterinaryMedicine, Haukeland University Hospital,University of Oslo, Institute of Public Health,Norwegian Food Safety Authority.Financial support: Ministry of Fisheriesand Coastal Affairs, Fish research capture.

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Shellfish andcrustaceansShellfish have a special ability tobioaccumulate undesirable substances andundesirable micro-organisms. Crustaceanscan also accumulate undesirable substancesto varying extents. On behalf of theNorwegian Food Safety Authority, NIFES iscurrently performing annual inspection andmonitoring of micro-organisms andundesirable substances in crustaceans,shellfish, sea-snails and crabs.

Good microbiological quality ofshellfish Shellfish can take up gut bacteria such as E.coli, enterococci and Salmonella from thewater in which they are growing. Levels ofE. coli and enterococci are determined inorder to identify faecal contamination(sewage), which is a potential source ofdisease.

Generally speaking, the results of the trialscarried out in 2010 indicated a high level ofmicrobiological quality. Of a total of 391samples analysed for E. coli, 92 % containedlevels below the upper limit for classificationin the A-range; shellfish from this range canbe sent directly for human consumption.Enterococci were demonstrated in seven of420 samples, but only in low concentrations.Salmonella were not found in any of the 94samples analysed.

Low content of undesirablesubstances in shellfish andcrustaceansNIFES’ monitoring of a range of undesirablesubstances provides knowledge of what arenormal levels in individual species ofcrustaceans, as well as of how these levelscompare with upper permitted limits.

In 2010, a total of 69 samples of musselswere taken, in addition to five samples ofking scallops, four samples of oysters and 19

crabs. None of the shellfish samplesexceeded European Union or Norwegianupper limits for undesirable substances inshellfish for human consumption. Levels oforganic environmental toxins were relativelylow in all the samples, but there was still anobvious effect of oil pollution in Aust-Agdereight or nine months after the “Full City”shipwreck.

Three of 14 samples of crab from the Saltenregion in the County of Nordland displayedcadmium concentrations that were higherthan the permitted limit. Crab brown meatalso contained relatively high concentrations,with up to 19 mg/kg wet weight. TheEuropean Union and Norway have not yet setupper limits on undesirable substances inbrown meat from crabs. On the backgroundof these results, an increase in the monitoringof edible crabs has now been implemented.

The study showed that Norwegian shellfishand crabs contain low levels of micro-organisms and undesirable substances, and

are therefore safe to eat, with the possibleexception of crabs from Salten. TheNorwegian Food Safety Authority’s shellmonitoring programme also covers algaltoxins, but this part is performed by theInstitute of Veterinary Medicine.


Research on mussels

The coast of Norway offers good conditionsfor producing mussels. However, duringcertain seasons of the year, the amount ofalgae available lies well below what isneeded for optimal growth of cultivatedmussels; this is due to a lack of the nutrientsalts that the algae themselves need in orderto grow. NIFES has previously studied howthese algae are taken up and excreted byvarious shellfish species.

To make use of artificial up-flows, freshwateris pumped down into deep water, where theconcentration of nutrient salts is higher. Thefreshwater is less dense that saltwater, andtherefore rises to the surface. In the process,the freshwater and saltwater mix, bringingthe nutrient salts up to the surface wherealgal production takes place. This processraises the concentration of algae whilepotentially hindering the occurrence of toxicalgae.

The amount of food that they consume hasbeen assumed to have a positive effect on theexcretion of diarrhoeal toxins in mussels, butfew studies have been performed undernatural conditions with a wide range of foodavailability. It is important to study thisproblem in order to evaluate what artificialup-flows could mean for mussel farmoperation. Another aspect of the algal toxinsituation concerns whether toxic algae wouldbecome more or less frequent with artificialup-flows.

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NIFES has been collaborating with theInstitute of Marine Research on a project onartificial up-flows in the Lysefjord in theCounty of Rogaland. Water from a powerstation is pumped down to nutrient-rich deepwater. The fresh water draws the bottomwater up to the surface, where it triples algalproduction within an area of 10 – 20 squarekilometres. NIFES’ part of the project was toperform detoxification tests on mussels fromone experimental and one control location inthe fjord. The trials have been carried out andthe analyses will be ready in 2012.

Collaboration: Institute of MarineResearch, University of Bergen, IFREMER,Lysefjord Research Station.Financial support: Research Council ofNorway.

Monitoring ofshipwrecks and sunken vessels

Wrecks and sunken vessels can houseenvironmental toxins, and such vessels are aproblem for food safety in case contaminantsshould leak out. NIFES therefore studies andmonitors the content of environmental toxinsin species caught in the vicinity of thesubmarine U-864 near the island of Fedje.NIFES is a member of the NorwegianCoastal Administration’s monitoring andcontingency planning groups.

Monitoring submarine U-864 near Fedje

When the German submarine was sunk bythe allied forces in June 1944, it was carryinglarge quantities of mercury, some of whichwas deposited on the seabed. Out ofconsideration for food safety, NIFES hasbeen monitoring mercury in fish and crabsfrom this area on behalf of the NorwegianCoastal Administration and the NorwegianFood Safety Authority since 2004. In 2011,samples were taken from around the wreck,as well as from four sea-miles to the southand four sea-miles to the north of the wreck.The results showed, as they had donepreviously, that levels of mercury in tusk andcrabs were generally below European Unionand Norwegian upper limits for food safety.

Only two out of 75 tusk contained levels ofmercury that exceeded the upper permittedlimit. The mercury content of tusk caughtclose to the wreck was higher than in thosetaken in open water in the Norwegian Sea

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and the Barents Sea, but these values did notdiffer greatly from those at other locations onthe coast of western Norway. Mercuryconcentrations were lower close to the wreckthan four sea-miles distant in either direction.

There has been no significant increase ordecrease between 2005 and 2011 in thecontent of mercury in tusk taken close to thewreck, although concentrations do varysomewhat from year to year. The levels aregenerally below the upper permitted limits. In claw- and brown meat from crabs caughtclose to the wreck, mercury concentrationswere somewhat higher than have been foundin other investigations of crabs on theNorwegian coast. Concentrations of mercurywere also clearly higher in crabs caught closeto the wreck than in those taken four sea-miles distant in either direction. Theconcentrations of mercury in the crabsamples from 2011 were slightly lower thanin 2004 – 2008, but higher than in 2009 and2010. This is probably due to seasonalvariations.

The results of the monitoring programmefrom 2005 up to and including 2011 add upto an indication that high levels of mercuryin crabs are related to contamination of thesediments in the vicinity of the wreck.

Although the mercury content of crabscaught close to the wreck is higher that whatwas found elsewhere, the concentrations arestill well below the upper limits for foodsafety in Norway and the European Union.The Norwegian Food Safety Authority hasalready recommended that women who arepregnant or breast-feeding should not eat

seafood from the area around the submarinewreck.

Crab brown meat has been exempted fromthese limits, but the Norwegian Food SafetyAuthority recommends in general that neitherwomen of child-bearing age nor childrenshould eat crab brown meat. The 2011analyses have not changed the food safetypicture.

Financial support: Norwegian CoastalAdministration.

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Management plansIn White Paper no. 12 (2001 – 2002) “Cleanand Rich Seas”, the Norwegian Parliamentconsidered that there is a need for betterintegrated management of Norwegianmaritime areas. The first step in this processwas the preparation of an integratedmanagement plan for the Barents Sea and theseas around Lofoten. To this end, workinggroups for acute pollution and formonitoring, and a Professional Forum for theBarents Sea, were appointed. NIFES isrepresented on all these bodies. TheMonitoring Group coordinates monitoringactivities in the Barents Sea that cover arange of different parameters, stock sizes ofseveral fish species and the pollutionssituation.

The management plan for the marineenvironment in the Barents Sea and the seasaround Lofoten was updated in a new White

Paper, no. 10 (2010 – 2011), in which foodsafety has been allocated a central position inseveral chapters. NIFES contributes to all theworking groups that deal with themanagement plan for the Barents Sea and theNorwegian Sea.

NIFES is also a member of the ScientificGroup for the North Sea and Skagerrak,which is chaired by the Climate andPollution Directorate (Klif), which draws upthe management plan for this region. In 2011,NIFES contributed its scientific expertise inthe field of seafood safety to thedevelopment of five sector studies ofconsequences, as well as two reports. Thereports and studies are important parts of thescientific basis of the management plan forthe North Sea and Skagerrak, which shouldbe ready in spring 2013.


Long-term monitoring

Undesirable substances in shrimp, capelinand polar cod are monitored on an annualbasis as a follow-up of the management planfor the Barents Sea. The aim is to documentconcentrations of undesirable substances andnote any changes in level over time. Acorresponding monitoring programme from2006 – 2010 found low levels of undesirablesubstances in shrimp, capelin and polar codfrom this area.

Samples of these species were taken at threedifferent positions in the Barents Sea. Thesehave been analysed for various metals andorganic environmental toxins, and the resultswill be processed and reported in 2012.

Financial support: Ministry of Fisheriesand Coastal Affairs. .

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All risk-benefit analyses concludethat seafood is safe and healthy,and that it should form part of ahealthy and varied diet. However,these evaluations also point to amajor need for knowledge of howpositive and negative componentsof seafood interact and whatoverall effects they have on ourhealth.

Selenium counteracts theeffects of mercury

Fish and seafood are rich in the mineralselenium, but they may also contain methylmercury, which is one of the most toxicforms of mercury found in nature. Mercuryhas particularly negative effects on thedevelopment of the nervous system duringthe early stages of embryonic development.Exposure to mercury can lead to damage tothe motor system, diminished ability to learnand memorise, and to damage to the sensorysystem in human beings. Research suggeststhat selenium counteracts the effects ofmercury, but our knowledge of how mercurycauses such damage and how it interacts withselenium is still limited.

NIFES is studying how mercury affects the

development of the nervous system inzebrafish embryos, when the femalezebrafish has eaten feed that contains eithermercury alone or in combination withselenium. Zebrafish are widely used as amodel system in studies of toxicity duringembryonic development. The results so farshow that mercury is transferred from themother to the embryo. This affects thegrowth of nerve fibres from nerve cells tomuscle cells, resulting in motor defects. Byadding selenium to the diet, the effects ofmercury can be slowed down, as seleniumleads to changes in the expression of genesthat control growth of nerve fibres from thenervous cells.

The uptake and excretion of methyl mercuryin adult females was also studied. So far, wehave found that mercury accumulates in

Interactions between undesirable substances and nutrients

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«By adding selenium to the diet, the effects of mercury can be slowed down»

muscle, liver and heart. Uptake is greatest inmuscle, and is reduced when selenium isadded to the diet. The studies also show thatselenium raises the rate of excretion ofmercury from muscular tissue.

NIFES is continuing to work towards anunderstanding of how selenium affectsmercury. Knowledge of how undesirablesubstances affect the early development ofthe nervous system is important, both for thesake of fish welfare and in order to ensurefood safety for consumers.

Collaboration: National Research Instituteof Fisheries Science, Japan.Financial support: Research Council ofNorway, and National Association ofFishery and Aquaculture Industries.

Omega-3 and methylmercury

This study looked at how the marine omega-3 fatty acids DHA and EPA can influence theeffects of the environmental toxin methylmercury, a particularly toxic compound ofmercury. When programmed cell death(apoptosis) was measured following exposureto methyl mercury, the fatty acid DHAincreased, while EPA reduced apoptosis.

Studies have shown that the injurious effectof DHA is probably related to increasedoxidative stress, while EPA probably protectscells via its effects on cell calciumregulation. A number of interactions betweennutrients and methyl mercury were alsoobserved in the study.

The results may help to focus attention oninteractions between nutrients andenvironmental toxins. The study also lays thefoundations for improved assessments ofinteractions between nutrients andenvironmental toxins in fish, and how thesemight impact seafood safety.

Collaboration: University of Bergen,University of Aberdeen, UK. Financial support: Research Council ofNorway.

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One of the most importantchallenges to health in the westernworld today is related to diet, notleast because we eat too muchsaturated fat and sugar, andperform too little physical activity.The World Health Organisation(WHO) is very concerned aboutthis trend, and is focusing sharplyon the rapidly growing incidence oflifestyle diseases, i.e. non-communicable diseases that includecardiovascular disease, obesity,diabetes, osteoporosis and mentalhealth problems.

The prevention of lifestyle diseasesvia healthier diets, more physicalactivity and stopping smoking hasbeen a high-priority topic for theWHO. People are generallyrecommended to increase theirconsumption of fish and otherseafood, and documentationregarding the benefits to health ofeating seafood will make animportant contribution to reach thegoal of increasing our consumptionof seafood.

So far, only the positive effects ofmarine omega-3 on cardiovascular disease have been sufficiently welldemonstrated. This is primarily because virtually all studies haveutilised cod-liver oil or fish oil rather than fish as such. Seafoodcontains a unique combination of proteins, vitamins, minerals andmarine omega-3 fatty acids. NIFES' research is aimed at improving ourunderstanding of the health benefits of the overall combination ofnutrients in seafood.

Seafood in our diet and its implications for our health

«People are generally recommended to increase their consumption of fish and otherseafood, and documentation regarding the benefits to health of eating seafood will makean important contribution to reach the goal of increasing our consumption of seafood»

Obesity and diabetesSevere overweight (obesity) is a known riskfactor for many diseases. Most of these arerelated to metabolic processes, and arecharacterised by inflammatory reactions,most of which, in turn, are directly related tofat tissue. Fat tissue is not, as was previouslybelieved, merely a storage site for surplusenergy, but an active organ that synthesisesand releases hormones and cytokines that canpromote inflammation in other organs of thebody. As body weight rises, the release ofinflammatory cytokines normally increases,partly because of the increased amount of fattissue, but also because the fat cells are

infiltrated by macrophages that also producecytokines. This is probably the reason whyobesity can be linked to the development ofreduced insulin sensitivity and subsequentlyto type 2 diabetes.

We know that a fat-rich diet, particularly incombination with carbohydrates, facilitatesthe development of obesity. However, studieshave shown that if the level of protein in thediet is increased, rodents can stay slim evenif they consume large amounts of fat andhave a high energy intake. Studiesperformed by NIFES have shown that micethat consume large quantities of protein stayslim because their brown fat cells proliferate.

Unlike white fat cells, which store energy,the brown fat cells have an elevated capacityto “burn” fat. The mitochondria in brown fatcells express a protein known as UCP1,which functions as an uncoupler in themitochondria. The energy released by brownfat cells during the “combustion” processitself is turned into heat, and the energy isthus transported out of the body. Brown fatcells are also among the body’s mosteffective means of taking up sugar, and inthis way, an elevated number of brown fatcells can also help to protect us against type2 diabetes.

Sugar and milk proteins contain similaramounts of energy. When mice consume adiet in which the sugar has been replaced bymilk proteins, their lowered feed conversionefficiency is therefore not due to reducedfeed intake.

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Significance of principalnutrients in the diet

Norwegian dietary advice, like that issued bythe WHO, recommends a larger intake of fishand other seafood. This is largely becauseomega-3 fatty acids in oily fish havedisplayed an ability to prevent cardiovasculardisease. Recent research findings suggest thatlean fish, which is low in omega-3 fattyacids, has positive effects in the preventionof type 2 diabetes, although what causes thiseffect is not known. NIFES is carrying outresearch on how lean sources of proteinaffect the development of obesity, type 2diabetes and cardiovascular disease.

ProteinsProteins are chains of amino acids of variouslengths. Hydrolysed protein is obtained byadding enzymes to a protein, in a processcalled hydrolysis. Hydrolysed proteinsconsist of free amino acids and short aminoacid chains. NIFES has previously shown

that replacing all the casein in the controldiet with hydrolysed salmon protein lowersblood glucose and insulin in rats. Thissuggests that rats fed scallop/cod proteinutilised their insulin better, which isimportant for avoiding the development oftype 2 diabetes.

NIFES has investigated whether we canreplace half of the casein with hydrolysedsalmon protein and still obtain the samepositive effects. We have also studiedwhether hydrolysed casein has identical, orsimilar, effects. The results of theseexperiments are not in agreement with earlierfindings, which showed that blood sugarlevels fall when all the casein is replaced byhydrolysed salmon protein in rats on high-fatdiets. This suggests that the ability ofhydrolysed salmon protein to lower bloodsugar is dependent on the amount that ismixed into the diet.

The study also shows that if we wish to

improve blood sugar regulation in rats fedhigh-fat diets, more than half of the caseinmust be replaced by hydrolysed salmonprotein. How this would work in humans hasyet to be documented.

NIFES has continued to study how proteinfrom different sources affects thedevelopment of obesity and lipid and glucosemetabolism in mice. Milk protein (i.e.casein), protein from filleted chicken breastand a mixture of proteins from scallops andcod fillets have been tested. The results so farindicate that scallop/cod protein cancounteract the development of obesity inanimals on a high-fat diet. Glucose tolerancealso appears to improve with scallop/codprotein in the diet in high-fat, high-sugar andmoderate western diets.

CarbohydratesIt is well documented that fish-oils canreduce the development of obesity and type 2

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diabetes in mice. NIFES has previouslyshown that it is not a matter of indifferencewhether the fat in the food is combined withsugar or with protein. We have nowinvestigated whether various combinations ofthe main nutrients affect the slimming effectof fish-oils.

The mice that had eaten fat together withsugar became significantly fatter than thosewho had eaten fat together with proteins. Infact, mice that had eaten fat together withproteins put on less weight than a third groupthat consumed a low-calorie diet. In thisrespect, fish-oils are no different from othertypes of fat.

Sugar was then replaced with various typesof starch found in foods such as pasta,potatoes and bread. In mice given fish-oiltogether with carbohydrates, blood sugarconcentrations rose, insulin production in thepancreas increased and their weight rose. Forthe sake of comparison, we combined this

diet with a drug that limited insulinproduction, and this procedure produced slimmice.

The results show that it matters which typeof food fish-oil is consumed together with.Sugar and other types of carbohydrate thatraise blood sugar levels cancel out theslimming effects of fish-oil. Research is nowunder way on the long-term effects ofconsuming fish-oil or vegetable oil togetherwith either sugar or protein. We know thatlow-carbohydrate diets can have a slimmingeffect in humans, but there are still questionsas to whether such diets can lose their effector be hazardous over a period of time. Inorder to study these questions, we have fedmice diets that are rich in fat and proteins orin fat and sugar throughout their lives.

Collaboration: Depts. of Biology andBasic Animal and Veterinary Sciences,University of Copenhagen, and BeijingGenomics Institute at Shenzhen.

Financial support: RUBIN, Ministry ofFisheries and Coastal Affairs, ResearchCouncil of Denmark, Research Council ofNorway.

Significance of undesirablesubstances in the diet

Previous studies have shown that fish-oilscan offer protection against the developmentof diabetes in rats and mice. On the otherhand, there is growing anxiety regarding theintake of persistent organic pollutants(POPs). In 2011, NIFES showed that rats fedunrefined fish-oils developed insulinresistance, which means that organs reactpoorly to insulin. Further work has looked atwhether environmental POPs in seafood havethe same effects as in fish-oil. Mice fed withordinary farmed salmon as part of a high-fatdiet became fat and were less protectedagainst the development of type 2 diabetesthan mice on a high-fat diet that did not

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include salmon. The level of environmentalPOPs in the salmon feed was relatively high,and this was reflected in the fatty tissue ofthe mice.A salmon fed fish-oils that had beenpurified of environmental POPs wassubsequently used in new diets for the mice.These diets contained lower levels of POPs,and a much smaller amount of POPaccumulated in the fat of the mice. Thesemice were leaner and had better insulinsensitivity than the mice that had beenexposed to higher levels of toxins.

Collaboration: Dept. of Biology, Universityof Copenhagen, INSERM,INRA, CarMeNLaboratory, University of Lyon, AarhusUniversity Hospital, Denmark.Financial support: Research Council ofNorway.

Relationship betweenomega-6 and vegetable fat There appears to be a close connectionbetween the amount of omega-6 fatty acids

in the diet and the development ofoverweight and obesity. Omega-6 is a type offat that is found for example in certainvegetable oils and ready-to-eat foods. Recentresults from an animal model show that ahigh intake of omega-6 leads tooverproduction of signalling compounds thatstimulate appetite, with the result thatanimals eat more and put on more weight.We eat less and less fat, while we becomefatter. The type of fat we eat thus seems tomean more for the development of obesitythan how much fat we consume. In the course of the past few decades,consumption of cooking oil has doubled inNorway, while total fat consumption hasfallen. Meanwhile, the number of overweightpeople has risen drastically.

On the basis of the above results, this is goodreason to investigate whether the rise inconsumption of cooking oil that contains ahigh proportion of omega-6, particularly soyaoil, maize oil and sunflower oil, could be acontributory factor to the development of

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overweight and obesity in Norway. In acollaborative project with scientists in theUSA, we have studied mice to see howvarious levels of intake of polyunsaturatedfats affect appetite and fat storage. Twogroups of mice were given different amountsof linoleic acid, which is a polyunsaturatedomega-6 fatty acid that is found in largeamounts in soya oil, maize oil and sunfloweroil. A third group was given a diet with ahigh content of omega-6, but also a certainproportion of marine omega-3.

The results showed that the group whose diethad the highest content of omega-6 ate more,and became far fatter, than the group whosediet contained little omega-6. The obesity-promoting effect of omega-6 was reducedwhen the diet was supplemented with marineomega-3.

A parallel experiment showed that mice thatwere fed a high proportion of omega-6,equivalent to current recommendations, puton much more weight than mice that were

given food with a low content of omega-6,irrespective of their level of food intake.

The body metabolises omega-6 to endothelialcannabinoids, which are signalling moleculesthat regulate appetite, feelings of hunger andenergy and fat storage. When the bodyproduces more of these signalling agents thanwe need, the feeling of hunger is notswitched off as it should be, so we eat morethan we need. Moreover, we store more ofthe food that we eat in the form of fat.

Omega-6 competes with omega-3 for roomin the cells of the body. A high intake ofomega-6 replaces omega-3 in the tissue. Thiscan influence a number of illnesses,including cardiovascular disease, whereomega-3 has been shown to have apreventive effect, while the effects of omega-6 can be the opposite. The body needs bothomega-6 and omega-3, but there is a problemwhen there is an imbalance between theintake of omega-6 and that of omega-3. Changes in farming and agriculture have led

to higher consumption of raw materialscontaining omega-6. This means that theomega-6 content of eggs, meat, milkproducts and fish, for example, has increased,while that of omega-3 has fallen. We eatmuch more meat than we used to, while ourconsumption of seafood, the main sources ofomega-3, has not increased. This reinforcesthe imbalance between omega-6 and omega-3.

Creating a better balance between omega-6and omega-3 consumption could be one ofthe keys to reducing and preventing obesityand its associated conditions such as type 2diabetes and cardiovascular disease. Whatremains to be done is to confirm the aboveresults via human trials.

Collaboration: National Institute of Health,Washington DC.Financial support: Research Council ofNorway.

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Mental healthMental health problems affect an ever-growing proportion of the population, andstudies show that countries where theconsumption of seafood is low have higherincidences of mental illnesses. Untilrecently, the positive effect of omega-3 fattyacids was only associated with

cardiovascular disease. Now we know thatthe omega-3 fatty acids DHA and EPA arealso important for the brain.

NIFES is studying how marine omega-3 fattyacids in fish and other types of seafood affectbrain processes, and we are attempting tounderstand the underlying mechanismsinvolved. As well as omega-3 fatty acids,seafoods also contain a unique combination

of nutrients. We therefore need to carry outmore food tests in which we study the effectsof eating fish and other seafood in an actualmeal, rather than just the effect of individualcomponents in capsules or tablets. Studies ofthis sort are needed because the effects ofeating fish and seafood may be very differentfrom the effects of individual nutrients.

Can seafood affectbehaviour?

In a study carried out in Bergen Prison,prisoners’ diets were surveyed and a foodtrial of oily fish was carried out. The aim ofthe study was to find out whether diet was ofany significance for solving problems thatrequire actively paying attention. The studyrevealed many positive aspects of theprisoners’ diets, although some of them didhave an inadequate diet. Fewer than 20percent of them managed the recommendedintake of vitamin D, a finding confirmed byblood sampling. When the participants in thestudy were divided into two groups

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according to their blood vitamin D levels, theresults showed that the group with thehighest vitamin D levels gave more correctresponses to cognitive problems that requireactive attention than the group with lowvitamin D blood status.

In a follow-up study from Sand Ridge Prisonin the USA, participants ate either salmon oran alternative dinner menu for 22 weeks. Theaim was to determine whether seafood canaffect underlying biological mechanismsrelated to auto-regulation and impulsecontrol. The results showed that the groupthat consumed salmon obtained an improvedomega-3 status. The results of thebehavioural measurements are still beingprocessed.

Collaboration: Ministry of Fisheries andCoastal Affairs, Nutrition Programme Board(University of Bergen), Centre for Researchand Education in Forensic Psychiatry(HUS)San Ridge Treatment Facility, USA.

Can seafood help overcomepostnatal depression?

Several studies have demonstrated a possiblelink between seafood consumption andmental health. Postnatal depression affectsbetween 10 and 15 percept of Norwegianmothers, while pregnant Norwegian womeneat less than half a portion of oily fish aweek. In the course of two projects, NIFEShas looked at how diet affects maternalmental health during and after pregnancy,and at neonatal development. The aim was tofind out whether seafood in the diet canimprove nutritional status and reduce amother’s psychological problems, and tostudy what this can mean for the child.

One of these studies is taking place atnational level, with participants from all partsof Norway. The other is local and deals withabout 100 families in Fjell Municipality nearBergen. Neither of the studies is finished, butinterim results from the local study show thatthe most depressed mothers have the lowest

levels of marine omega-3 fatty acids in thecirculation. It also appears that seafood in theform of sandwich spread or topping was themost important source of omega-3 fatty acidsin that study.

The results of these studies could provide theauthorities and health-care personnel with ascientific basis for providing clear advice onwhat pregnant women should eat, and why. Itwould also be possible to offer adviceregarding the diets of new mothers and theirinfants. These studies will provide betterknowledge about the relationship betweendiet, nutritional status and risk factors forproblems of post-natal mental health.

Collaboration: Regional Centre for Childand Adolescent Mental Health (UniHelse/RBUP Vest), Fjell Municipality.Financial support: Ministry of Fisheriesand Coastal Affairs, Uni Helse.

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Spine and bone health

Effects of marine oils onback pain

Skeletomuscular problems are widespread inthe population, and they contribute to half ofNorway’s incidence of long-term sick-leave.In collaboration with Uni Helse, NIFES isstudying the effects of cognitive treatmentcombined with dietary supplements onpatients who are taking sick-leave for chroniclower back pain. NIFES is responsible for theanalysis of blood samples for a range of fatty

acids after the patients have consumed thediet supplement. The aim is to get patientsback to work, and to look at the effects of thesupplement on pain relief.

Almost 600 back pain patients from all overthe country have been recruited either tocognitive therapy in the form ofconversations or to therapy via dietarysupplements (seal oil or soya oil). Aftertherapy, they will be followed up for twoyears and their rates of sick-leave will becompared. People with problems of backpain often mention that they also suffer fromother subjective health problems, such asmild depression and colds. NIFES is studyingwhether the consumption of seafood andomega-3 supplements can relieve subjectivehealth problems, not least because omega-3is believed to have positive effects on pain.These studies will be carried out with the aidof a range of questionnaires and bymeasuring levels of omega-3 fatty acids inthe bloodstream. No results are available asyet.

Collaboration: Uni Helse, University ofBergen, various Norwegian clinics andhospitals. Financial support: Ministry of Fisheriesand Coastal Affairs, Research Council ofNorway, Helse Vest, Miks DA, GC RieberFoundation, University of Bergen/Unifob.

Vitamin D from salmon -just as effective as dietarysupplements

The calcium in our bones is continuouslyreplaced throughout life. When more calciumis removed than enters the system, ourskeletal system becomes weaker, our bonesbecome more fragile (osteoporosis) and weare more likely to suffer fractures. People inthe initial stages of osteoporosis arerecommended to take calcium and vitamin Dsupplements. Oily fish and fish liver, as wellas a few other types of food, are our onlynatural dietary sources of vitamin D.

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Vitamin D increases calcium uptake in thegut in humans, and is essential for calciumbalance in the body. Vitamin K appears toensure that calcium is incorporated in bone.

NIFES has had salmon produced that are richin vitamins D and K, and these have beenused in feeding trials in which menopausalwomen participated. These women areparticularly liable to develop osteoporosis,and the aim of the experiment is to study theeffects of vitamins D and K from salmon andvitamin D in tablet form on bone health inthese women.

Three groups of women were fed salmoncontaining different levels of vitamins D andK, and one group was given vitamin D andcalcium as a dietary supplement. Thewomen’s vitamin D and vitamin K statuswere measured at the start and end of thestudy in order to find out whether theenriched salmon had any effect on theirvitamin status. Vitamin D from salmon andin tablet form produced equally large rises inthe women’s vitamin D status, while bonedegradation was also reduced in theparticipants whose vitamin D status hadimproved. The study also showed that twosalmon meals a week are sufficient tomaintain good omega-3 status.

Collaboration: Skretting, University ofBergen (Haukeland University Hospital).

Financial support: Research Council ofNorway, Ministry of Fisheries and CoastalAffairs.

Effects of omega-3 on health

Does the source of omega-3influence its uptake?

A study carried out by the Centre for ClinicalStudies in Bergen investigated whether thesource of marine omega-3 influences itsuptake by healthy people. Sixty-eightsubjects consumed either salmon, omega-3juice or cod liver oil capsules, and the studyexamined how EPA and DHA were taken upby the body. The amounts of EPA and DHAeaten were equivalent to three times theEFSA’s recommended levels for healthypersons. No other dietary omega-3 wasconsumed by the participants during thetrials.

Interim results show that the level of omega-3 in red blood cells was relatively high at thestart of the study. These levels rose in all the

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groups after six weeks, and they increased towhat has been proposed as the lowerthreshold for low risk of cardiovasculardisease. The were no group differencesbetween the three sources of omega-3.Dosage rather than source appears to affectthe uptake of omega-3 in the blood ofhealthy persons. However, a larger-scalestudy over a longer period of time, andincluding a control group, is needed for theseresults to be confirmed.

Vitamin D status at the start of the studyshowed that most of the participants laywithin the normal range of values. In morethan 40 percept, however, the level waslower than desirable. Taking cod liver oilraised vitamin D levels.

A number of studies have also beenperformed on mice, in the course of whichvarious sources of marine omega-3 wereused. The results of the analyses from thesestudies are currently being processed.

Collaboration: Centre for Clinical Studies(Cenclin), Uppsala University, University ofOslo, University of Debrecen, Hungary. Financial support: Smartfish, ResearchCouncil of Norway, Ministry of Fisheriesand Coastal Affairs, Marine HarvestIngredients.

Whale oil as a source ofomega-3

NIFES has carried out a pilot study at theCentre for Clinical Studies in Bergen withthe aim of finding out whether whale oil is agood source of marine omega-3 fatty acidscompared to cod liver oil. Whale oil is notcurrently on the market, and little researchhas been done on its effects on health, partlybecause of its high content of environmentalcontaminants. This study utilised refinedwhale oil that satisfies the requirementsregarding these contaminants.

Research on omega-3 fatty acids started in

the 70s, when the diet of the Inuit inGreenland was studied. The Inuit eat acertain amount of flesh and blubber ofwhales and seals. Whale oil is rendered fromwhale blubber, in this case of minke whales.From the 90s on, the effects on health ofconsuming shale oil were studied in Tromsø,and it was found that healthy people reducedtheir risk of cardiovascular disease, includingthrombosis, after consuming 15 ml a day forsome months.

In this pilot study, 43 healthy subjects weregiven capsules of whale oil or cod liver oilfor six weeks. The doses of marine omega-3were identical (0.8 g EPA + DHA) in bothgroups, and were equivalent to more thanthree times the lowest recommended dosagefor preventing cardiovascular disease(EFSA). Tentative results suggest that therewere no differences in the uptake of omega-3in the blood between the whale oil and codliver oil groups. The participants in the studyhad a moderately high intake of seafood andsupplementary marine omega-3 before the

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start of the study. Nevertheless, the omega-3blood index rose; i.e. the percentages of EPAand DHA in red blood cells increased from 7to 8, implying a reduced risk ofcardiovascular disease.

Although whale oil contains only half asmuch marine omega-3 as cod liver oil, itcould still be a good source of marineomega-3. The omega-3 fatty acids in whaleoil are incorporated into the fat molecules ina somewhat different way than they are incod liver oil. The study suggests that whaleoil administered to healthy persons could bejust as good a source of omega-3 as cod liveroil, and thus reduce the risk of cardiovasculardisease.

This study was carried out during the winter,when sunlight is in short supply in Norway.It is then that it is particularly important toensure an adequate intake of vitamin D viathe diet. Vitamin D concentrations in thebloodstream rose in the participants who tookcod liver oil, which is a very good source of

vitamin D. Whale oil, on the other hand,contains little vitamin D, and in this study ithad no effect on vitamins levels in thecirculation.

Collaboration: Centre for Clinical Studies(Cenclin), Uppsala University, University ofOslo.Financial support: Karsten Ellingsen AS,G.C. Rieber Funds, Myklebust Trading AS,Innovation Norway, Fisheries andAquaculture Industry Research Fund.

Lean fish are a source ofomega-3

Oily fish are a well-known source of omega-3, but a NIFES project has recentlydiscovered that eating lean fish can raiselevels of the omega-3 fatty acid DHA in thecirculation. DHA is of particular importancefor the development and optimal functioningof the eye and brain.

Thirty healthy men and women aged between

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20 and 40 were given a daily meal of 150 gcod, salmon or potatoes (control group) fortwo weeks. Analysis of blood samples takenafter the trials revealed a significant increasein circulating DHA in both of the groupsgiven fish. The content of triglyceride fats(TAG) in the blood also fell in both of thesegroups.

Collaboration: Oslo and AkershusUniversity College, Institute of Public Health,University of Oslo.Financial support: Research Council ofNorway, Ministry of Fisheries and CoastalAffairs, Oslo and Akershus UniversityCollege, Institute of Public Health,Norwegian Cancer Society.

Fish-milt and its effects onhealth markers

It is well-known that fish-milt can improvethe immune system response in humanbeings. This is due particularly to its highnucleotide (DNA) content. Fish-milt makesup a large proportion of the by-products ofcod and herring caught during the majorseasonal fisheries. Milt from these fisherieshas a significant potential for the productionof bioactive agents that can be used in thefood and pharmaceutical industries. Previousstudies have shown that nucleotides fromsalmon and cod affect human immune cells.Fish-milt has a high content of the omega-3fatty acids EPA and DHA.

A NIFES pilot study investigated whetherwhole fish-milt can have more positiveeffects on health markers than nucleotides oromega-3 fatty acids alone. The study showed

that fish-milt affects health markers such asgenes and proteins in cultures of humanimmune cells, and that it has a more positiveeffect than nucleotides, EPA or DHA alone.

This is the first time that it has beenscientifically demonstrated that fish-milt hasan effect on human health biomarkers. AnMSc project at NIFES will study whetherfish-milt can affect salmon health. This willenable us to determine whether fish-milt infeed can improve resistance to disease.Current types of feed offer significantchallenges to fish health compared totraditional feeds based on fish-meal and fish-oils. Components that are capable ofstrengthening the immune system and healthof fish will play a decisive role in theproduction of robust fish.

Financial support: RUBIN.

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The use of fish-meal and fish-oil infarmed salmon feed is declining,due to high prices and reducedavailability. Changes in thecomposition of feeds affect thehealth of fish, which in turn affectsthe fish consumer. NIFES iscurrently performing a project thatevaluates the entire seafoodproduction chain, from fish-feed tothe table. This is a continuation of aEuropean Union project calledAQUAMAX that was coordinatedby NIFES.

Today, feed for cultivated fish contains anever-increasing proportion of plantingredients. In this project, NIFES islooking at whether the salmon of today andtomorrow, which consume high levels ofplant oils, will be as healthy as traditionalfarmed salmon given feed based on fish-oil.When the proportion of fish-oil is reduced,

the amount of undesirable substances, whichmay promote obesity, also goes down. But sodoes also the amount of marine omega-3fatty acids, which have been shown toprevent obesity. This makes it unlikely thateating either “yesterday’s” or “tomorrow’s”salmon will have any altered effect on humanhealth.

Replacing a large proportion of the marineingredients of feed with plant protein andplant oil has been shown to enable salmon toutilise their feed efficiently and to grow well,

but it has also been shown the concentrationof fat in the blood increases, there is morebelly fat and more fat in liver. NIFES iscurrently working to identify the causes ofthis by studying e.g. changes in thecomposition of fatty acids in the body.

Collaboration: Skretting, VI, NVH,University of Florida, University ofCopenhagen.Financial support: Research Council ofNorway, Skretting ARC.

Seafood in an whole food chain production perspective

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NIFES analyses nutrients and undesirablesubstances in foodstuffs, primarily fish andother types of seafood, for the authorities. Onthe basis of these data and research in thefields of fish nutrition, human nutrition,seafood safety and monitoring, NIEFSprovides advice to the authorities, industryand the public sector in pursuit of theirefforts to ensure that seafood is healthy andsafe to eat.

NIFES is accredited to Standard NE-EN ISO17025, and in accordance with Norwegianobligations under the EEA agreement hasbeen appointed as national referencelaboratory (NRL) for undesirable substances,nutrients and microbiological analyses. Asnational reference laboratory, NIFES isresponsible for organising national laboratoryaudits, analysing random samples fromaccredited laboratories, providing scientificadvice and consultations, and adviceaccreditation of analyses.

NIFES continuously develops and improvethe efficiency of methods for analysing awide range of substances in seafoods. Forexample, the Institute has developedanalytical methods for minerals that providemore rapid results. We have also developedcell models for studying the effects ofinteractions between nutrients andundesirable substances in seafood. NIFESperforms analyses of all minerals anddevelops methods and methodologicaladaptations, and keeps itself up to date asregards international developments in thefield of reference functions.

NIFES also runs a number of accreditedmicrobiological methods for the analysis ofmedicine residues and bacteria in seafoodsand seafood products.

Norwegian Accreditation (NA) performsannual audits of our laboratory system, andonce every five years our laboratories'

quality-assurance system undergoes a morecomprehensive evaluation. In 2010, NIFES’accreditation was renewed for a further fiveyears. This is a guarantee that NIFESoperates in accordance with relevantstandards, and that our internal laboratoryroutines are good enough to ensure adequatetraceability and control of data. The methodsemployed by NIFES are also regularly testedvia ring tests, which provide a benchmark ofhow our methods perform vis-à-vis thoseused by other laboratories. NA requiresaccredited companies to participate in ringtests.

At present, NIFES is accredited to utilisearound 60 methods of analysing undesirablesubstances and nutrients in foods, includingfish and other types of seafood.

NIFES is a national reference laboratory

Aquaculture NutritionNIFES has editorial responsibility for thejournal “Aquaculture Nutrition”, which ispublished by Wiley-Blackwell. There is asteady increase in the number of manuscriptssubmitted for publication, particularly frommajor aquaculture nations such as China, Indiaand Brazil. The journal currently has a chiefeditor and three assistant editors.

The growth in the number of articles publishedby the journal, and the fact that it needs toincrease the number of pages per issue,indicate that it is internationally recognisedwithin its primary field of fish nutrition. Thejournal has plans to become fully electronic inthe course of the next few years.

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Teaching and training In collaboration with the University of Bergen,NIFES offers teaching at MSc and PhD level.Seven members of NIFES' scientific staff heldadjunct appointments, with responsibility forteaching courses, at the University of Bergen in2011. NIFES participated in teaching a total ofnine courses.

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Teaching at the University of Bergen

Nutrition in cultivated aquaticorganismsMAR 353 (10 course credits)

Food microbiology, with specialreference to seafoodMAR 255 (10 course credits)

Food chemistry and analysisMAR 352 (15 course credits)

Food toxicologyMAR 353 (10 course credits)

Macro- and micro-nutrientsNUTR 207 (10 course credits)

Human nutrition - Macro-nutrientsNUTR 300 (10 course credits)

Human nutrition - Micro-nutrientsNUTR 301 (10 course credits)

Methods in nutritional scienceNUTR 310 (5 course credits)

Biomedical nutritional physiologyBMED 381 (5 course credits)

The National Institute of Nutrition and SeafoodResearch (NIFES) is a research institute withadministrative duties, related to the Ministry of Fisheriesand Coastal Affairs. The Institute performs research onfish nutrition and on how the consumption of fish andother types of seafood affects our health. The Instituteprovides scientific advice to the government, foodauthorities and industry in support of their efforts to

ensure that seafood is healthy and safe to eat. The institute is independent of the fishery sector and itsresearch results are made generally available to thepublic.

NIFES operates the following modern laboratories: theLaboratory for Nutrient Analysis, the Laboratory forUndesirable Substances, The laboratory for elementsand the Laboratory for Molecular Biology. The Instituteperforms national reference functions for a number ofanalytical methods for foodstuffs, as well as for parasitesin seafood, and is accredited for some 60 methods toNorwegian Standard NS-EN ISO/IEC 17025.

In collaboration with NIFES, the University of Bergenoffers teaching at MSc and PhD level in human and fishnutrition. NIFES also hosts apprentices in laboratoryoperation. NIFES has editorial responsibility for theinternational journal “Aquaculture Nutrition”.

NIFES does research in the following areas:

• Safe and healthy seafood

• Fish nutrition

www.nifes.no

NIFESP.O. Box 2029 NordnesNO-5817 Bergen, Norway

Tel: +47 55 90 51 00Fax: +47 55 90 52 99E-mail: [email protected]

Visitor address: Strandgaten 229 www.rein

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Research news 2012