Endret lokalitetsstruktur i produksjonsområde 3 - vurdert virkning på spredning av lakselus, pankreassykdom og infektiøs lakseanemi

Havforskningsinstituttet (HI) og Veterinærinstituttet (VI) fikk en felles bestilling av Nærings- og fiskeridepartementet om å analysere effektene av ulike scenarioer for en ny lokalitetsstruktur i produksjonsområde 3 som kan gi mindre spredning av lakselus, ILA og PD mellom lokalitetene. Det er antatt at mindre smitte mellom lokalitetene vil gjøre det lettere å drive oppdrett av laks, med lave luseverdier, bedre fiskehelse og fiskevelferd, og dermed øke bærekraften. Ved hjelp av biofysisk modellering og nettverksanalyse av spredning av lakselus, PD og ILA mellom lokaliteter er det anslått at flytting av produksjon fra særlig smittespredende lokaliteter til mindre smittespredende lokaliteter, kan redusere den totale smitten mellom lokalitetene. Analysene viser at ved å fjerne tilfeldige lokaliteter hvor man flytter biomassen til de resterende lokalitetene vil redusere smittepresset, men ikke like effektivt som ved en strategisk flytting av biomasse fra de “verste” til de beste lokalitetene med tanke på smittespredning. I et av scenariene som er testet med Havforskningsinstituttet sine modeller er det indikert at smitten mellom lokalitetene kan reduseres med 46% for lakselus og 30% for virus, ved å redusere fra dagens 135 lokaliteter ned til 100 matfisklokaliteter – dette uten å redusere den totale produksjonen i produksjonsområdet. På tilsvarende måte indikerer Veterinærinstituttet sin lusemodell at en ved tilfeldig fjerning av halvparten av alle lokaliteter og refordeling av biomassen til andre lokaliteter i PO3 vil få rundt regnet ca. 20% færre voksne hunnlus, 20% færre andre mobile lus, og 20% færre behandlinger i hele området. Denne effekten blir større, dersom de lokalitetene som lukkes er strategisk valgt, dvs. at de er valgt på bakgrunn av hvor mye de bidrar til spredning av lus basert på HI sin nettverksmodell. Det synes dermed å være et stort potensial for å redusere smitten mellom lokaliteter ved å redusere antall lokaliteter i PO3 og samtidig opprettholde produksjonen. Imidlertid er det behov for mer omfattende analyser og utredning av ny lokalitetsstruktur, der en tar hensyn til en rekke andre faktorer som bl.a. om lokalitetene tåler økt biomasse med tanke på organisk belastning, selskapsstruktur, muligheter for sonevise utsett, samt påvirkning på vill laksefisk før en kan anbefale konkret ny lokalitetsstruktur i PO3.publishedVersio

The DECIDE project: from surveillance data to decision-support for farmers and veterinarians

Farmers, veterinarians and other animal health managers in the livestock sector are currently missing sufficient information on prevalence and burden of contagious endemic animal diseases. They need adequate tools for risk assessment and prioritization of control measures for these diseases. The DECIDE project develops data-driven decision-support tools, which present (i) robust and early signals of disease emergence and options for diagnostic confirmation; and (ii) options for controlling the disease along with their implications in terms of disease spread, economic burden and animal welfare. DECIDE focuses on respiratory and gastro-intestinal syndromes in the three most important terrestrial livestock species (pigs, poultry, cattle) and on reduced growth and mortality in two of the most important aquaculture species (salmon and trout). For each of these, we (i) identify the stakeholder needs; (ii) determine the burden of disease and costs of control measures; (iii) develop data sharing frameworks based on federated data access and meta-information sharing; (iv) build multivariate and multi-level models for creating early warning systems; and (v) rank interventions based on multiple criteria. Together, all of this forms decision-support tools to be integrated in existing farm management systems wherever possible and to be evaluated in several pilot implementations in farms across Europe. The results of DECIDE lead to improved use of surveillance data and evidence-based decisions on disease control. Improved disease control is essential for a sustainable food chain in Europe with increased animal health and welfare and that protects human health

Cardiomyopathy syndrome in Atlantic salmon Salmo salar L.: A review of the current state of knowledge

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Cardiomyopathy syndrome in Atlantic salmon Salmo salar L.: A review of the current state of knowledge

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Susceptibility of pike-perch Sander lucioperca to a panel of ranavirus isolates

The host range of ranaviruses was investigated by challenging pike-perch (Sander lucioperca) with the following ranavirus isolates: epizootic haematopoietic necrosis virus (EHNV), European sheatfish virus (ESV), European catfish virus (ECV), pike-perch iridovirus (PPIV), short-finned eel virus (SERV) and frog virus 3 (FV3). Pike-perch fry were bath-challenged at 12°C and 22°C at 5 weeks post hatching, and the challenge was repeated with EHNV and PPIV in older fish (15 weeks post hatching) at higher densities. A third batch of fish was subjected to intraperitoneal (i.p.) and cohabitation challenge with EHNV, ESV, ECV and PPIV at 16°C. Statistically significant mortality was observed in EHNV-challenged fish at both temperatures in the five week old fish. No mortalities were seen in older fish challenged with EHNV and PPIV. High mortalities were registered in i.p.-challenged fish, but not in cohabitated fish. Virus re-isolation was possible from the youngest bath-challenged fish in all challenge trials and the i.p.-challenged fish, but not from older fish or cohabitated fish. Susceptibility of pike-perch to ranaviruses appears to be dependent on age of fish and challenge route. The study shows that pike-perch are susceptible to infection with ranavirus under certain conditions, and it is suggested that this be considered when reviewing the legislation on notifiable diseases

Susceptibility of pike-perch Sander lucioperca to a panel of ranavirus isolates

The host range of ranaviruses was investigated by challenging pike-perch (Sander lucioperca) with the following ranavirus isolates: epizootic haematopoietic necrosis virus (EHNV), European sheatfish virus (ESV), European catfish virus (ECV), pike-perch iridovirus (PPIV), short-finned eel virus (SERV) and frog virus 3 (FV3). Pike-perch fry were bath-challenged at 12 °C and 22 °C at 5 weeks post hatching, and the challenge was repeated with EHNV and PPIV in older fish (15 weeks post hatching) at higher densities. A third batch of fish was subjected to intraperitoneal (i.p.) and cohabitation challenge with EHNV, ESV, ECV and PPIV at 16 °C. Statistically significant mortality was observed in EHNV-challenged fish at both temperatures in the five week old fish. No mortalities were seen in older fish challenged with EHNV and PPIV. High mortalities were registered in i.p.-challenged fish, but not in cohabitated fish. Virus re-isolation was possible from the youngest bath-challenged fish in all challenge trials and the i.p.-challenged fish, but not from older fish or cohabitated fish. Susceptibility of pike-perch to ranaviruses appears to be dependent on age of fish and challenge route. The study shows that pike-perch are susceptible to infection with ranavirus under certain conditions, and it is suggested that this be considered when reviewing the legislation on notifiable diseases

Susceptibility of pike Esox lucius to a panel of Ranavirus isolates

In order to study the pathogenicity of ranaviruses to a wild European freshwater fish species, pike Esox lucius fry were challenged with the following Ranavirus isolates: epizootic haematopoietic necrosis virus (EHNV), European sheatfish virus (ESV), European catfish virus (ECV), pike-perch iridovirus (PPIV), New Zealand eel virus (NZeelV) and frog virus 3 (FV3). The fry were infected using bath challenge at 12 and 22°C. Significant mortalities were observed at 12°C for EHNV, ESV, PPIV and NZeelV. Background mortality was too high in the experiments performed at 22°C for any conclusions about viral pathogenicity at this temperature to be drawn. Viruses could be re-isolated from samples from all challenged groups, and their presence in infected tissue was demonstrated using immunohistochemistry. The findings suggest that pike fry are susceptible to EHNV, ESV, PPIV and NZeelV and can be a vector for ECV and FV3. Statistical analysis of the factors associated with positive virus re-isolation showed that the number of fish in the sample influenced the outcome of virus re-isolation. Moreover, the likelihood of positive virus re-isolation significantly differed among the 6 viral isolates. The temperature from where the sample was taken and the number of days after infection were not associated with the probability of a positive virus re-isolation