Annual report on health monitoring of wild anadromous salmonids in Norway 2018 - Screening of migrating Atlantic salmon (Salmo salar) postsmolts from the Trondheim fjord for viral infections

Very few virus infections found in migrating postsmolts from the Trondheim Fjord Commissioned by the Norwegian Food Safety Authority, the Institute of Marine Research has studied the occurrence of several potential disease-causing viruses that are common in salmon farming in imigrating postsmolts from Trondheim fjord in 2016. The postsmolts were caught in the mouth of the fjord, which is a national salmon fjord without fish farming activity, and therefore it is unlikely that this fish is exposed to infections from salmon farming. The incidence of SAV, PRV1, ILAV and PMCV infections was tested using the real-time RT-PCR method. SAV, PRV1, ILAV were not detected in any of the postsmolts. Low concentration of PMCV was detected in a single fish. The results show that the occurrence of these viruses is very low in wild salmon postsmolts in this area of the fjord.publishedVersio

Effects of laboratory salmon louse infection on osmoregulation, growth and survival in Atlantic salmon

Anadromous Atlantic salmon (Salmo salar) rely on long ocean migrations to build energy stores for maturation and spawning. In seawater, wild Atlantic salmon are threatened by high salmon lice (Lepeophtheirus salmonis) infestation levels resulting from intensive salmonid sea-cage aquaculture. Salmon lice infection can cause a stress response and an osmotic imbalance in the host. The lice infection intensity threshold values for these responses, however, remain to be identified in Atlantic salmon. In order to define this under laboratory conditions, individually tagged F1 wild origin Atlantic post-smolts (40 g) were infected with salmon lice copepodids or left as uninfected controls. Twenty-eight days post infection, infected post-smolts had a mean of 0.38 (range of 0.07–0.9) mobile lice g−1 fish weight. During this period, specific growth rates (SGRs) were lower in infected than control fish (0.4 vs 1.0% day−1). Higher plasma Na+, Cl− and osmolality in infected fish also indicate osmoregulatory impairment. SGR correlated negatively with plasma Na+, Cl−, osmolality and cortisol in the infected, but not in the control group. Infection intensity (lice g−1 fish) correlated positively with mortality rate and plasma Na+, Cl−, osmolality and cortisol and correlated negatively with SGR and condition factor. Calculated lice intensity threshold values for changes in plasma ions were 0.18 lice g−1 for plasma Cl−, and 0.22 lice g−1 for plasma Na+. Moribund infected fish occurred at infection intensities above 0.2 lice g−1, and these fish had extreme plasma Cl−, Na+, osmolality and cortisol levels. There was a positive correlation between plasma cortisol and plasma Na+, Cl− and osmolality in infected fish. This study provides vital information that can be used to define thresholds in the monitoring and conservation of wild Atlantic salmon populations affected by aquaculture-driven salmon lice infestations.publishedVersio

Estimert dødelighet for utvandrende postsmolt av laks 2012-2020 - Rapport til Mattilsynet OK-program 56827 – Lakselusovervåking

For å estimere dødeligheten grunnet lakselus sluppet fra oppdrettsanlegg til utvandrende postsmolt av laks fra de lakseførende elvene med gytende biomasse > 10 kg i de 13 ulike produksjonsområdene, er det benyttet en Virtuell Postsmoltmodell (VPS). I denne rapporten er estimatene kategorisert basert på om det er <10%, mellom 10 og 20% eller over 30% estimert dødelighet.publishedVersio

Estimert dødelighet for utvandrende postsmolt av laks 2012-2021 — Rapport til Mattilsynet OK-program 56827 – Lakselusovervåking

For å estimere dødeligheten grunnet lakselus sluppet fra oppdrettsanlegg til utvandrende postsmolt av laks fra de lakseførende elvene med gytende biomasse > 10 kg i de 13 ulike produksjonsområdene, er det benyttet en Virtuell Postsmoltmodell (VPS). I denne rapporten er estimatene fra 401 lakseførende elver vist i kart for hver av de 13 produksjonsområdene for årene 2012-2021, og kategorisert basert på om det er <10%, mellom 10 og 30% eller over 30% estimert dødelighet. Usikkerheten i estimatene er beregnet ved å se på effekten av å fremskynde eller utsette utvandringen, samt å endre laksens toleranse for lakselus.publishedVersio

Annual report on health monitoring of wild anadromous salmonids in Norway 2020 - Screening of wild Atlantic salmon (Salmo salar) postsmolts for viral infections

The Institute of Marine Research has investigated the prevalence of infectious salmon anaemia virus (ISAV) and salmonid alphavirus (SAV, PD-virus) infections in migrating wild Atlantic salmon postsmolts captured in 2019 in three fjord systems located in three aquaculture production areas (PO2-4). These areas have had a sporadic case of ISA and a stable high incidence rate of PD, as well as a very high aquaculture intensity. The fish were collected as part of the national salmon lice monitoring program in the outer parts of the Bokna (N=132), Hardanger (N=110) and Sogne (N=110) fjords by trawling during the period May-June. ISAV was detected in two postsmolts from Hardanger fjord and SAV in one smolt from Sogne fjord. The Ct-value of SAV-positive fish was very high (38.9) which may suggest a false positive result. The findings from the current report indicate a very low prevalence of these viruses in wild migrating postsmolts. These findings complement and corroborate our previously reported data and may suggest that prevalence of ISAV or SAV infections in wild salmon postsmolts are not significantly influenced by the occurrence of these infections in fish farming.publishedVersio

Annual report on health monitoring of wild anadromous salmonids in Norway 2021 - Screening of Atlantic salmon (Salmo salar) postsmolts for viral infections

Havforskningsinstituttet har undersøkt utbredelsen av infeksiøs lakseanemi virus (ILAV) og salmonid alfavirus (SAV, PD-virus) infeksjoner i utvandrende vill atlantisk postsmolt fanget i 2020 i tre fjordsystemer lokalisert i tre akvakultur produksjonsområder (PO3, 5, 12). Fisken ble samlet inn som en del av NALO-programmet i de ytre delene av fjordene; Hardangerfjorden (N = 100), Romsdalsfjorden (N = 100) og Altafjorden (N = 100) ved tråling i perioden mai-juni. SAV ble påvist i én postsmolt fra Hardangerfjorden og ILAV i én smolt fra Altafjorden. Høy Ct-verdi (37,6) i den SAV-positive fisken kan imidlertid tyde på et falskt positivt resultat. ILAV påvisningen var sannsynligvis av den apatogene HPR0-varianten av viruset. Funnene fra den nåværende rapporten indikerer en svært lav forekomst av disse virusene i vill migrerende postsmolt av laks. Disse funnene utfyller og støtter våre tidligere rapporterte data, og kan antyde at utbredelsen av ILAV- eller SAV-infeksjoner i villaks postsmolt ikke er signifikant påvirket av forekomsten av disse infeksjonene i fiskeoppdrett.publishedVersio

Annual report on health monitoring of wild anadromous salmonids in Norway 2022 - Screening of Atlantic salmon (Salmo salar) postsmolts from Boknafjorden, Hardangerfjorden and Romsdalsfjorden for viral infections

The Institute of Marine Research has investigated the prevalence of infectious salmon anaemia virus (ISAV), salmonid alphavirus (SAV, PD-virus), piscine orthoreovirus 1 (PRV-1), piscine myocarditis virus (PMCV) and infectious pancreatic necrosis virus (IPNV) infections in migrating wild Atlantic salmon postsmolts captured in 2021 in three fjord systems located in three aquaculture production areas (PO2, 3 and 5). The fish were collected as part of the national salmon lice monitoring program in the outer parts of Boknafjord (N = 50), Hardangerfjord (N = 57) and Romsdalsfjord (N = 73) by trawling during the period May-June. SAV was detected in 2 postsmolts from Romsdalsfjord. PRV-1 was detected in 11 (6%) of postsmolts (8 from Boknafjord, 1 from Hardangerfjord and 2 from Romsdalsfjord). Low concentrations of PMCV-RNA were detected in 19 (11 %) of postsmolts (13 from Boknafjord and 6 from Romsdalsfjord). ISAV and IPNV were not detected in any of the test fish. Generally, the virus-positive fish had high Ct-values which may indicate very low virus concentrations. The results in the current report showed that migrating postsmolts from fjords had a very low occurrence of virus infections common in Norwegian aquaculture. These findings complement and corroborate our previously reported data and may suggest that prevalence virus infections in wild salmon postsmolts is not significantly influenced by the occurrence of these infections in fish farming.Annual report on health monitoring of wild anadromous salmonids in Norway 2022 - Screening of Atlantic salmon (Salmo salar) postsmolts from Boknafjorden, Hardangerfjorden and Romsdalsfjorden for viral infectionspublishedVersio

Self-supervised learning: When is fusion of the primary and secondary sensor cue useful?

Self-supervised learning (SSL) is a reliable learning mechanism in which a robot enhances its perceptual capabilities. Typically, in SSL a trusted, primary sensor cue provides supervised training data to a secondary sensor cue. In this article, a theoretical analysis is performed on the fusion of the primary and secondary cue in a minimal model of SSL. A proof is provided that determines the specific conditions under which it is favorable to perform fusion. In short, it is favorable when (i) the prior on the target value is strong or (ii) the secondary cue is sufficiently accurate. The theoretical findings are validated with computational experiments. Subsequently, a real-world case study is performed to investigate if fusion in SSL is also beneficial when assumptions of the minimal model are not met. In particular, a flying robot learns to map pressure measurements to sonar height measurements and then fuses the two, resulting in better height estimation. Fusion is also beneficial in the opposite case, when pressure is the primary cue. The analysis and results are encouraging to study SSL fusion also for other robots and sensors

Risikorapport norsk fiskeoppdrett 2020 : Risiko knyttet til dødelighet hos utvandrende postsmolt laks som følge av utslipp av lakselus fra fiskeoppdrett

Havforskningsinstituttet har siden 2011 gitt ut en årlig risikorapport for norsk fiskeoppdrett med fokus på miljøeffekter og dyrevelferd. Arbeidet med rapporten har vist at akvakultur har et svært komplekst risikobilde, og det er varierende kunnskapsnivå og grad av tilgjengelige overvåkningsdata knyttet til de ulike miljøpåvirkningene. Lakselus og rømt oppdrettslaks regnes per i dag som de største truslene for villaksen og i 2017 ble det innført en handlingsregel basert på lakselus som miljøindikator som regulerer kapasitetsendringer i oppdrettsnæringen (Trafikklyssystemet). Der ekspertgruppen i Trafikklyssystemet beskriver nåværende status i produksjonsområdene basert på de siste to årene, ønsker vi med denne risikovurderingen å skape økt forståelse og innsikt rundt de antatt viktigste risikofaktorene knyttet til effekten av lakselus på utvandrende postsmolt laks, hvordan disse samspiller, og konsekvensen av disse. Argumentasjonen og vurderingene våre bygger på data og annen tilgjengelig kunnskap fra perioden 2012-2019.publishedVersio