Marine Biotoxin Monitoring


Since September 2013, Tolowa Dee-ni' Nation has been submitting shellfish samples to the California Department of Public Health (CDPH) in Richmond for analysis and detection of naturally occurring marine toxins that will inform local and statewide health advisories and quarantines.

Razor Clam Samples

Health Concerns

Domoic acid (DA) is a naturally occurring toxin that is related to a "bloom" of a particular single-celled diatom called Pseudo-nitzschia, while Paralytic Shellfish Poisoning (PSP) is related to a "bloom" of single-celled dinoflagellates called Alexandrium. The conditions that support the growth of Pseudo-nitzschia and Alexandrium are impossible to predict. Crustaceans, fish and shellfish are capable of accumulating elevated levels of both toxins without apparent ill effects on the animals. Elevated levels of these toxins in crustaceans, fish and shellfish pose a significant risk to the public if these adulterated products are consumed. Domoic acid and PSP can be fatal to people if consumed in high doses.


Symptoms of domoic acid poisoning can occur within 30 minutes to 24 hours after eating toxic seafood. In mild cases, symptoms may include vomiting, diarrhea, abdominal cramps, headache and dizziness. These symptoms disappear within several days. In severe cases, the victim may experience trouble breathing, confusion, disorientation, cardiovascular instability, seizures, excessive bronchial secretions, permanent loss of short-term memory (a condition known as Amnesic Shellfish Poisoning), coma or death.

Paralytic Shellfish Poisoning symptoms begin within a few minutes to a few hours after eating toxic shellfish. Symptoms begin with tingling and numbness of the lips, tongue and fingertips. Later symptoms are lack of balance, lack of muscle coordination, slurred speech and problems in swallowing. Complete paralysis and death can occur in severe cases.

Traditional Foods

There are no mechanisms for these toxins to accumulate in lat (seaweed), therefore it would be safe to consume. Duu-ma (anemones) should also be safe to eat.

Units & Sampling

  • Paralytic Shellfish Poisoning (PSP) toxins:
    • Units = microgram/100 grams (μg/100 g)
    • Alert level = 80 μg/100 g
  • Domoic Acid (DA) levels:
    • Units = parts per million (ppm)
    • Alert Level = 20 ppm

Mussel samples are taken from around Hunter Rock and Prince Island. Razor Clam samples are taken from South Beach and Crescent Beach when tides allow.

For more information call the Biotoxin Information line at 800-553-4133 or visit the California Department of Public Health website.

Next Sample Dates

  • Razor Clams: TBD
  • Mussels: October dates TBD


Shellfish gathered are frozen and sent to CDPH for analysis. Mussels are analyzed whole, while Razor clam viscera (guts) and muscle are analyzed separately.

Annual Mussel Quarantine: May 1 - October 31

Please see the posted Quarantine Order HERE (and in Spanish HERE).  

  1. Dee-LHat (Mussel)
  2. Met-'e (Razor Clam)

September 13, 2022
August 3, 2022ND<2.5
July 19, 2022ND<2.5
June 2, 2022ND<2.5
May 5, 2022ND<2.5
April 25, 2022ND<2.5
March 25, 2022ND<2.5
February 24, 2022ND<2.5
January 13, 2022ND<2.5
December 1, 202133<2.5 
November 2, 202133<2.5
September 27, 2021348.4
September 10, 2021362.5
August 30, 2021ND ND
July 13, 2021NDND
June 2, 202136 ppmND
May 12, 2021NDND
April 14, 202134 ppmND
March 25, 2021NDND
February 8, 2021NDND
January 8, 2021NDND
December 10, 202039 ppmND
October 15, 202040 ppm< 2.5 ppm
September 3, 202040 ppmND
August 5, 2020ND< 2.5 ppm
June 22, 2020NDND
May 29, 2020NDND
May 28, 202037 ppmND
April 27, 202037 ppmND
April 2, 2020< 2.5 ppmND
March 12, 2020< 2.5 ppmND
January 23, 2020ND< 2.5 ppm
December 9, 201941 ppm7.2 ppm
November 25, 201976 ppm2.5 ppm
October 27, 201937 ppm2.5 ppm
July 3, 2019< 2.5 ppmND
June 5, 2019NDND
April 24, 2019NDND
April 12, 201937 ppmND
March 4, 2019< 2.5 ppmND