DAO 117:171-176 (2016)  -  DOI: https://doi.org/10.3354/dao02944

Summer mortalities and detection of ostreid herpesvirus microvariant in Pacific oyster Crassostrea gigas in Sweden and Norway

Stein Mortensen1,*, Åsa Strand2, Torjan Bodvin3, Anders Alfjorden4, Cecilie K. Skår1, Anders Jelmert3, Anna Aspán4, Lisbeth Sælemyr1, Lars-Johan Naustvoll3, Jon Albretsen

1Institute of Marine Research, PO Box 1870 Nordnes, 5817 Bergen, Norway
2Department of Marine Sciences, Göteborg University, Tjärnö, 45296 Strömstad, Sweden
3Institute of Marine Research, Flødevigen Research station, Nye Flødevigveien 20, 4817 His, Norway
4National Veterinary Institute, Sweden (SVA), Department of Animal Health and Antimicrobial Strategies, 751 89 Uppsala, Sweden
*Corresponding author:

ABSTRACT: The Pacific oyster Crassostrea gigas has recently expanded its range in Scandinavia. The expansion is presumably a result of northwards larval drift. Massive settlements were recorded in many areas along the Swedish west coast and southern Norway in 2013 and 2014. After the spawning season in 2014, the temperature of the surface water peaked at 24-26°C. After this period, high and sudden mortalities occurred in a Swedish hatchery and in wild populations along the Swedish west coast and south coast of Norway. Surveys and collected data showed that mortalities mainly occurred during 3 wk in September. All size classes were affected, and affected populations displayed a patchy distribution with heavily affected and unaffected populations in close proximity. Flat oysters Ostrea edulis and blue mussels Mytilus edulis were unaffected. Ostreid herpesvirus (OsHV) was detected in moribund Pacific oyster spat as well as in surviving adults. The virus was identified as OsHV-1 μvar. This is the first detection of this variant in Scandinavia, showing that OsHV-1 μvar is present in areas with recent establishments of Pacific oysters, and where there is no aquaculture of this species.


KEY WORDS: Pacific oysters · Crassostrea gigas · Summer mortalities · Scandinavia · Ostreid herpesvirus · OsHV-1 μvar


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Cite this article as: Mortensen S, Strand Å, Bodvin T, Alfjorden A and others (2016) Summer mortalities and detection of ostreid herpesvirus microvariant in Pacific oyster Crassostrea gigas in Sweden and Norway. Dis Aquat Org 117:171-176. https://doi.org/10.3354/dao02944

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