General Information

Event name: US-91-012
Nature of the harmful event:
Seafood toxins
Event directly affected:
Toxicity detected: Yes (Approximate range: 10,000 g STXeq / 100 g.)
Associated syndrome: PSP
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: Yes
Event occurred before in this location: Yes (1927, 1929, 1932, 1954, 1962, 1963, 1964, 1965, 1966, 1970, 1971, 1976, 1980, 1981, 1982, 1984, 1986, 1988, 1989, 1990.)
Individuals to contact: ROSS, Maria R.

Location & Date

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Location: Latitude: , Longitude:
General location information: Marin County., California.
HAB Area code(s): US-21
Additional location information: Stinson Beach/south rocks, Rodeo Beach, Kehoe Beach (Wild Sea Mussels); Drakes Bay/Chimney Rock, Tomales Bay/Lawson's Landing (Sentinel Sea Mussels); Drakes Estero/Bed#12, Tomales Bay/Lease #M430-10 (Wild Bay Mussels, Sentinel Bay Mussels); Tomales Bay/Marconi Cove and Leases #M430-10, 11, 14 (Cultured Bay Mussels); Drakes Bay/Chimney Rock LBS (Sentinel Pacific Oysters); Drakes Estero/Beds 3, 8, 12, 22, Tomales Bay/Marconi Cove, Lawson's Landing, Leases =M430-02, 02B, 10, 11, 14, HIOC Wet Storage (Cultured Pacific Oysters); Tomales Bay/Lease #M430-10, 11 (Manila Clam); Tomales Bay/Clam Island (Gaper Clam).
Bloom event dates (yyyy/mm/dd):
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information: January, February, June, July, August, September high above alert levels; March, October, November high measurable but below alert concentrations.


Causative organism known: Yes
Causative Species/Genus: Alexandrium catenella ( 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:
Growth: Advected
In situ
Growth Comments Both advected population from the northern coastal areas and in situ growth most likely contributed to the bloom condition.
Additional Environmental information: No data available.

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Sentinel sea mussel Saxitoxins STX eq 10,000 Bioassay-Mouse
Wild sea mussel Saxitoxins STX eq 1,900 Bioassay-Mouse
Wild Bay mussels Saxitoxins STX eq 4,100 Bioassay-Mouse
Cultured bay mussels Saxitoxins STX eq 2,400 Bioassay-Mouse
Gaper clam viscera Saxitoxins STX eq 2,500 Bioassay-Mouse
Manila clam Saxitoxins STX eq 110 Bioassay-Mouse
Sentinel Pacific oyster Saxitoxins STX eq 1,200 Bioassay-Mouse
Cultured Pacific oysters Saxitoxins STX eq 2,200 Bioassay-Mouse
Kit used: No Type of kit used:
Additional information:
Economic losses:
Management decision: The magnitude and geographical extent of the toxic Alexandrium catenella bloom resulted in the issuance of a special quarantine order by the Director of Health Services on July 25, 1991 to include all bivalve shellfish taken by sport harvesters. On July
Additional harmful effect information: These high concentrations occurred during the months of July and August.