General Information

Event name: US-03-022
Nature of the harmful event:
Seafood toxins
Event directly affected:
Toxicity detected: Yes (Approximate range: 1 - 117 ppm DA.)
Associated syndrome: ASP
Unexplained toxicity: No
Species implicated in toxin transmission (transvector): None occurred.
Report the outcome of a monitoring programme: Yes
Event occurred before in this location: Yes (Yes, coastal razor clams have been affected by domoic acid producing algae blooms b3 at least 3 other extended closures.)
Individuals to contact: CANNON, Deborah F.

Location & Date

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Location: Latitude: , Longitude:
General location information: Clatsop Beaches (northern most county) and c, Oregon.
HAB Area code(s): US-22
Additional location information: This event was evident along the entire coast line, north to south, but mainly on the Clatsop beaches where razor clam habitat is abundant. Shellfish sampled from coastal bays did not reach toxic levels during this event. The entire coast of Oregon began the calendar year of 2003 closed for razor clam harvesting due to domoic acid levels in these highly prized clams. In October 2002, domoic acid levels increased from <3 to 117 ppm by Dec 2002, on the most popular razor clamming beach on the northern Oregon coast called Clatsop Beach. Beaches on the central and southern coast were also affected starting in late Oct 2002 with levels rising to 61 ppm by November 2002.Domoic acid levels in the north coast or Clatsop Beach razor clams declined from the 90s to 40s ppm ranges during Jan to May, 2003. In June and July levels ranged widely from the 40 20 ppm range. On July 15th Clatsop Beach went into a juvenile protection closure. August and Sept saw all sites on Clatsop Beach less than 20 ppm except one site at 21 ppm; re-sampling for this site was 14 ppm. After Oct 1 Clatsop Beach was opened for all harvest. There was still one sample of 29 ppm but a resample 3 days later had 3 sample sets from the same site with all less than 10 ppm. Bimonthly testing on Clatsop Beach since Oct 2003 has continued trending downward in 2003 to less than 10 ppm at all sites with several less than 5 ppm for domoic acid.Other species of clams- softshells and butters; mussels and oysters (Pacifics), on the north coast showed no detectable levels of domoic acid all year round.There was apparently a significant domoic acid bloom on the central and southern coast of Oregon during 2003 which prevented razor clams on these beaches from purging the domoic acid levels they had retained from the 2002 event. Domoic acid levels in razor clams ranged widely from 85 40 ppm domoic acid on these beaches during the months of Jan April, 2003. Then, during May and June of 2003, domoic acid levels appeared to jump to a higher range of 86 287 ppm. During this same period mussels, other types of clams and oysters, which had previously been below detection for domoic acid, were found with 1.6 to 15 ppm domoic acid.The non-razor clams and mussels quickly dropped to less than 1 ppm domoic by July. But the central and south coast razor clams stayed in the 100 40 ppm range until late fall when sampling became difficult due to high surf and big swells. These areas (from Seaside, OR to California border) have been closed to razor clamming since Nov 2002 and remain closed at the time of writing this 2003 summary, March 2004.
Bloom event dates (yyyy/mm/dd): Start: 2003-01-01, End: 2003-01-10
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information: Ongoing for central and south coast beaches


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: 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 Comments
Additional Environmental information:

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Razor clams, Mussels, Other bay clams. Domoic Acid DA eq 287 ppm LC
Kit used: Type of kit used:
Additional information:
Economic losses: Closure has unknown but significant impact on commercial razor clam processors and recreational/tourism in the area.
Management decision: Commercial and recreational closure required to comply with FDA and assure public safety. Recreational closure required to assure public safety. Commercial bait harvesting is also closed to prevent any contaminated product from entering commerce.
Additional harmful effect information:
Updated at 03:47 on 26 Jun 2020