All beaches in Island County continue to be closed to the harvest of all species of shellfish because of dangerously high levels of marine biotoxins, according to the state Department of Health.

The closure affects all species of clams, geoducks, oysters, mussels and invertebrates like moon snails. Marine biotoxins are produced by microscopic algae that are naturally present in marine waters, but are usually at levels too low to be considered harmful.

Clam and mussel seasons in Puget Sound generally run through August and September, but not this year.

Warm temperatures, sunlight and nutrient-rich waters can lead to “blooms” of this algae at times and can raise the level of marine biotoxins to a level that the state Department of Health warns may become dangerous.

Cooking does not rid the shellfish of the marine biotoxins. Harvesters simply have to wait for the amount of toxins to return to safer levels.

Symptoms of poisoning include tingling in the lips and tongue that spreads to fingers, toes and other extremities. It could result in difficulty breathing, which can lead to death by suffocation.

Harvesters should check the state’s shellfish safety map before grabbing a bucket: bit.ly/3Cv19Gr.