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: 11/27-29
  • Mussels: 11/26


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  SEE NOTICE HERE

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

October 30, 2023393.9
September 28, 2023407.6
August 18, 202342<2.5
July 20, 2023ND
June 21, 2023ND<2.5
May 26, 2023ND< 2.5
May 8, 2023NDND
April 28, 2023NDND
March 20, 2023ND<2.5
February 17, 2023NDND
January 19, 2023NDND
December 19, 2022ND< 2.5
November 22, 202246<2.5
October 24, 2022ND3
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