Harmful Algal Information System: Event US-23-013

General Information

Event name:	US-23-013
Country:	UNITED STATES
Nature of the harmful event:	Seafood toxins
Event directly affected:	Shellfish
Toxicity detected:	Yes (Approximate range: California Mussel (Mytilus californicus) 89 µg/100 g, cultured bay mussel 42 ug/100 g, pacific oyster 40 ug/100 g, razor clam viscera 43 ug/100 g.)
Associated syndrome:	PSP
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:	California - Del Norte, Humboldt, Mendocino, Sonoma, and Marin, San Mateo, Santa Cruz, Monterey Counties, 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: 2023-07-21, End: 2023-08-30
Additional date-related information:	PSP detected (< 80 ug/100 g) May-December

Microalgae

Causative organism known:	Yes
Causative Species/Genus:	Alexandrium 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:

Growth Comments

Additional Environmental information:

Toxin Assay Information

Species containing the toxin	Toxin type	Toxin details	Max. concentration	Assay type
California Mussels	Saxitoxins		89 ug/100g	Bioassay-Mouse
Pacific Oysters	Saxitoxins		40 ug	Bioassay-Mouse
Cultured Bay Mussels	Saxitoxins		42 ug	Bioassay-Mouse
Razor Clams	Saxitoxins		43 ug	Bioassay-Mouse

Kit used: Yes

Type of kit used: NeoGen

Additional information:

Shellfish homogenates are received on ice, extracted, and a Neogen rapid test determines whether the mussel sample is positive or negative. Mussel samples that are positive on NeoGen are then tested using a mouse bioassay to determine concentration of PSP toxins. All other species are only tested with mouse bioassay.

Economic losses:

Management decision:

Additional harmful effect information:

Created at 07:58 on 8 Apr 2025