General Information

Event name: US-20-016
Nature of the harmful event:
High Phyto concentration , Seafood toxins
Event directly affected:
Toxicity detected: Yes (Approximate range: Razor Clam meat (individual clams), 180 ppm; Dungeness Crab viscera, 46 ppm; California Mussel (Mytilus californicus), 11 ppm)
Associated syndrome: ASP
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: Yes (California Department of Public Health - Marine Biotoxin Monitoring Program)
Event occurred before in this location: Yes
Individuals to contact: ZUBKOUSKY-WHITE, Vanessa

Location & Date

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Location: Latitude: , Longitude:
General location information: Del Norte, Humboldt, Marin, Northern California
HAB Area code(s): US-21
Additional location information:
Bloom event dates (yyyy/mm/dd):
Quarantine levels dates (yyyy/mm/dd): First detection: 2020-02-08, End: 2020-08-19
Additional date-related information:


Causative organism known: Yes
Causative Species/Genus: Pseudo-nitzschia spp. ( 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: Oxygen content (nL/L): Wind velocity:
Temperature (°C): Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: Current Velocity:
Nutrient information:
Temperature Range During Event: Max: °C, Min: °C
Salinity Range During Event:
Bloom location in the water column:
Growth Comments
Additional Environmental information:

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
California mussel Domoic Acid 11ppm LC
Razor clam Domoic Acid 180ppm LC
Dungeness crab Domoic Acid 46ppm LC
Kit used: Type of kit used:
Additional information: Razor clams are known to store/retain domoic acid in their meat tissue at high levels long after associated pseudo-nitzschia blooms have subsided. Mussels and oysters do not store domoic acid in this way and none tested above 11 g/g (commercial or otherwise) the entire year.
Economic losses: Recreational fishery closure for razor clams was in place for the entire year due to samples frequently testing above the advisory threshold. No commercial shellfish growing areas were closed due to domoic acid all of 2020.
Management decision: Recreational fishery closure for Razor clams in place the whole year. Domoic acid levels were never high enough in commercial oyster and mussel growing areas to warrant any closures or management decisions.
Additional harmful effect information:
Created at 12:18 on 20 Apr 2021