Norwegian Scientific Committee for Food Safety (VKM) Doc.no 09/808-Final Risk Assessment of Recirculation Systems in Salmonid Hatcheries Opinion of the Panel on Animal Health and Welfare of the Norwegian Scientific Committee for Food Safety Date: 10.01.12 Doc. no.: 09-808-Final ISBN: 978-82-8259-048-8 VKM Report 2012: 01 1 Norwegian Scientific Committee for Food Safety (VKM) Doc.no 09/808-Final Risk Assessment of Recirculation Systems in Salmonid Hatcheries Brit Hjeltnes (chair of ad hoc group) Grete Bæverfjord Ulf Erikson Stein Mortensen Trond Rosten Peter Østergård 2 Norwegian Scientific Committee for Food Safety (VKM) Doc.no 09/808-Final Contributors Persons working for VKM, either as appointed members of the Committee or as ad hoc experts, do this by virtue of their scientific expertise, not as representatives for their employers. The Civil Services Act instructions on legal competence apply for all work prepared by VKM. Acknowledgements The Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM) has appointed an ad hoc group consisting of both VKM members and external experts to answer the request from the Norwegian Food Safety Authority. The members of the ad hoc group are acknowledged for their valuable work on this opinion. The members of the ad hoc group are: VKM members Brit Hjeltnes (Chair), Panel on Animal Health and Welfare Ulf Erikson, Panel on Animal Health and Welfare Stein Mortensen, Panel on Animal Health and Welfare External experts Grete Bæverfjord, Nofima Marin, Sunndalsøra Trond Rosten, SINTEF Fisheries and Aquaculture Peter Østergård, Sp/F Aquamed, Faroe Islands Other contributors to the assessment are Frode Mathisen, Anders Fjellheim and Brit Tørud. A special thanks to Bendik Terjesen for his contribution to this risk assessment. Assessed by The report from the ad hoc group has been evaluated and approved by Panel on Animal Health and Welfare Panel on Animal Health and Welfare: Olav Østerås (Chair), Knut E. Bøe, Ulf Erikson, Brit Hjeltnes, Kristian Hoel, Stein Mortensen, Rolf Erik Olsen og Espen Rimstad Scientific coordinator from the secretariat: Ingfrid Slaatto Næss 3 Norwegian Scientific Committee for Food Safety (VKM) Doc.no 09/808-Final Summary Background: To ensure good animal welfare in Norwegian salmonid hatcheries, certain water quality- related issues and various water quality parameters must fulfill the requirements set in the Regulations relating to Operation of Aquaculture establishments, and the water quality should be kept within the suggested safe levels according to these regulations issued by the authorities. When these regulations were issued, most hatcheries used flow-through systems with a continual renewal and exchange of water. In the spring of 2009 (when this risk assessment was first planned), 10-15 hatcheries recirculated their tank water. Because of an increasing interest in recirculation systems, and the fact that in the last two years other hatcheries have started with recirculation systems as well, the authorities expect that there will be a shift towards recirculation systems in the coming years. To be able to judge whether existing legislation is adequate in safeguarding fish welfare in hatcheries where water is recirculated, the Norwegian Food Safety Authority requested the Norwegian Scientific Committee for Food Safety (VKM) to conduct an assessment of the current situation and whether, or to which degree, a risk of injury, disease or other unnecessary suffering exists. The assessment is limited to salmon and rainbow trout in freshwater systems. To prepare the scientific background necessary to answer the questions from the Norwegian Food Safety Authority, the VKM Panel on Animal Health and Welfare established an ad hoc- group consisting of 6 national and international experts. The international expert came from the Faroe Islands. The group was chaired by Dr. Brit Hjeltnes from the Panel on Animal Health and Welfare. The Panel on Animal Health and Welfare supports the conclusions from the ad hoc group. Conclusions: Based on literature data and practical experiences from recirculating aquaculture systems (RAS), possible environmental effects on fish welfare were assessed. It is clear that there is a risk that the water quality in RAS can deteriorate and cause severely compromised welfare for the fish. On the other hand, a well-managed RAS can in fact stabilize, or even improve water quality, resulting in better welfare compared with some flow-through systems. Monitoring of key water quality parameters (dissolved oxygen, pH/CO2, Total Ammonia Nitrogen (TAN), nitrite, total gas pressure and temperature) is considered essential for safeguarding the welfare of the fish. Adequate quality assurance of the analytical methods is a prerequisite to ensure correct readings of relevant water quality parameters. Routine monitoring of fish behaviour, morphology (e.g. fins, gills and skin), production data (e.g. growth and food conversion ratio), as well as mortalities is also important. Suggested maximum or lower limits for most relevant water quality parameters exist. The Panel is of the opinion that these limits should, however, be considered as guidelines only since the existing water quality criteria are not based on results from commercial (RAS) conditions. A semi-quantitative risk assessment (risk = probability x consequence) was carried out. In the RAS considered here, the highest risk factors were considered to be elevated levels of nitrite 4 Norwegian Scientific Committee for Food Safety (VKM) Doc.no 09/808-Final - (NO2 ) and total gas saturation, excessive feeding, and insufficient removal of particles. Proper operational routines of the biofilter are essential to provide a healthy and stable aqueous environment. In particular, RAS can be vulnerable in the initial phase after start-up of the biofilter (inadequate removal of ammonia and nitrite). Since overfeeding and faeces cause fouling of the water in the fish tanks, a quick removal of particles is important, before the particles dissolve or disintegrate. Adequate dimensioning of the RAS is a prerequisite, and the fish farmers must ensure that the biomass kept in the system shall not exceed the maximum intended level at any one time. If microorganisms (pathogens) enter RAS, there is an increased risk that they will multiply and eventually cause an adverse impact on fish health and welfare. In such cases, it may be difficult to implement adequate disinfection procedures without affecting the stability of the biofilter. With proper expertise and relevant management, it is nevertheless possible to maintain good fish health and welfare in RAS. Safe operation of RAS requires good knowledge of water chemistry and the potential hazards involved that might cause compromised fish welfare. Therefore, proper training of personnel operating RAS is required. Water chemistry in RAS can be quite different from what the fish is naturally exposed to in nature or in aquaculture flow-through systems. Data gaps: Some specific data gaps were recognized related to water quality parameters determined under RAS conditions. More research is needed to better understand how the water quality in RAS affects chronic stress, health and fish welfare. Sammendrag Bakgrunn: For å sikre god dyrevelferd i settefiskanlegg for laks og regnbueørret er det nødvendig at ulike miljøbetingelser, inklusive grenseverdier for ulike vannkvalitetsparametre, oppfyller bestemte krav i henhold til eksisterende regelverk (’Driftsforskriften’). Da regelverket i sin tid ble utformet var det i all hovedsak vanlig i oppdrettsnæringen å benytte gjennomstrømningsanlegg (kontinuerlig utskifting av vannet i fiskekarene). Våren 2009, da dette oppdraget fra Mattilsynet først ble planlagt, var det imidlertid 10-15 settefiskanlegg i Norge som brukte resirkulert vann. For tiden er det en økende interesse for resirkuleringsanlegg, og i løpet av de siste to årene har flere kommet til. En regner med at det vil bli stadig mer utbredt med slike anlegg i de kommende årene. For å kunne bedømme om eksisterende lovgiving fremdeles er tilstrekkelig til å sikre god fiskevelferd i settefiskanlegg, har Mattilsynet anmodet Vitenskapskomiteen for mattrygghet (VKM) om å gjennomføre en vurdering av dagens situasjon med hensyn til risiko for skader og sykdom, og om fisken påføres unødvendige lidelser når den holdes i kar med liten, eller minimal vannutskifting (resirkuleringsanlegg). Oppdraget er begrenset til oppdrett av atlantisk laks og regnbueørret i ferskvannsfasen. For å gjennomgå det vitenskapelige grunnlaget som var nødvendig for å besvare de spesifikke spørsmål fra Mattilsynet, etablerte VKM - Faggruppe for dyrehelse og dyrevelferd – en ad hoc gruppe som bestod av fem nasjonale eksperter og en internasjonal ekspert fra Færøyene. Gruppen ble ledet av dr. Brit Hjeltnes fra Faggruppe for dyrehelse og dyrevelferd. Faggruppen slutter seg til konklusjonene i rapporten fra ad hoc-gruppen. 5 Norwegian Scientific Committee for Food Safety (VKM) Doc.no 09/808-Final Konklusjoner: Basert på litteraturdata og gjennomgang av praktisk erfaring fra drift av resirkuleringsanlegg er det utredet hvordan ulike miljøforhold eventuelt kan påvirke dyrevelferden. Vannkvaliteten i resirkuleringsanlegg kan forringes i betydelig grad med de følger at fisken utsettes for dårlige betingelser med hensyn til stress, helse og velferd. Imidlertid, når slike oppdrettssystemer drives på en god og forsvarlig måte, kan vannkvaliteten stabiliseres, og endog forbedres. Dette kan danne grunnlag