Harmful Algal Information System: Event US-23-011

General Information

Event name:	US-23-011
Country:	UNITED STATES
Nature of the harmful event:	Seafood toxins
Event directly affected:	Shellfish , Aquatic Mammals
Toxicity detected:	Yes (Approximate range: California Mussel (Mytilus californicus) 7.4 ppm, Cultured Bay mussel 31 ppm, pacific oyster 29 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:	Northern California, HAB Area code(s): US-21
Additional location information:	domoic acid detected (< 20 ppm) January - July, September, October
Bloom event dates (yyyy/mm/dd):
Quarantine levels dates (yyyy/mm/dd):	First detection: 2023-01-20, End: 2023-10-29
Additional date-related information:

Microalgae

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:

Growth Comments

Additional Environmental information:

Toxin Assay Information

Species containing the toxin	Toxin type	Toxin details	Max. concentration	Assay type
California Mussel	Domoic Acid		19 ppm	LC-MS
Razor Clam	Domoic Acid		59 ppm	LC-MS

Kit used: No

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.

Economic losses:

Recreational fishery closure for razor clams was in place for a potrion of the year due to samples frequently testing above the advisory threshold.

Management decision:

Additional harmful effect information:

California sea lions, Guadalupe fur seal, Southern sea otter all showed signs of domoic acid poisoning in this region. Several strandings were reported.

Created at 07:41 on 8 Apr 2025
Updated at 07:45 on 8 Apr 2025