General Information

Event name: NO-92-003
Country: NORWAY
Nature of the harmful event:
Seafood toxins , Mass mortalities
Event directly affected:
Natural Fish , Aquaculture Fish , Humans
Toxicity detected: Yes (Approximate range: 26,000 MU.)
Associated syndrome: PSP
Unexplained toxicity: No
Species implicated in toxin transmission (transvector): Bivalve molluscs
Report the outcome of a monitoring programme: Yes
Event occurred before in this location: Yes (A few historical records and more or less regular occurrences the recent years, however, the spatial and temporal extent may vary significantly form one year to another.)
Individuals to contact: DAHL, Einar , TANGEN, Karl , VARRAN, Gesche Torp

Location & Date

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Location: Latitude: 62.500000, Longitude:
General location information: , NORTH WEST COAST.
HAB Area code(s): NO-03 NO-04 NO-05
Additional location information: The highest toxicity was found in Tromso and Trondheimsfjord.
Bloom event dates (yyyy/mm/dd):
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information: May-June.


Causative organism known: Yes
Causative Species/Genus: Alexandrium excavatum (1,000,000 cells/L)
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information:
Event-related bibliography:

Environmental Conditions

Weather: Turbidity (NTU): Wind direction:
Stratified water: No Oxygen content (nL/L): Wind velocity:
Temperature (°C): Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: Current Velocity: 0
Nutrient information:
Temperature Range During Event: Max: °C, Min: °C
Salinity Range During Event:
Bloom location in the water column:
In situ
Growth Comments Mainly due to in situ growth.
Additional Environmental information: See attached file

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Sand-dwelling bivalves Saxitoxins 678 MU/100 g Bioassay-Mouse
Modiola modiolus (horse mussel) Saxitoxins 26000 MU/100 g Bioassay-Mouse
Fish gut Saxitoxins 544-377 MU/100 g Bioassay-Mouse
Kit used: Type of kit used:
Additional information: Toxins recorded above the action level according to mouse bioassay. Highest recording was 19200 ME (see attached file)
Economic losses: One fish farm in the inlet of the Trondheims fjord lost about 80 tons of salmon and rainbow trout, whereas one farm in the main fjord lost about 10 tons of salmon in 5-6 other farms in the area.
Management decision: Harvesting was locally banned. The public was warned against picking toxic mussels.
Additional harmful effect information:
Updated at 04:09 on 2 Dec 2019