Harvesters should not eat clams, mussels, oysters, geoducks and scallops from Penn Cove, Saratoga Passage and Holmes Harbor because of dangerous biotoxin levels, officials announced this week.

Any shellfish harvested from the areas after Monday, Aug. 16 should be disposed of.

The closure does not include crab, according to information from the state Department of Health and the Island County Public Health Department natural resources division.

Although crab feed on impacted shellfish, the levels of biotoxins are not high enough to make crab meat unsafe to eat. However, toxins tend to accumulate in the yellow-white fat and guts in a crab and should be avoided.

Marine biotoxins occur naturally in small amounts and are produced by certain types of phytoplankton. The level of biotoxins can become dangerous in the summer months because of the combination of warmer temperatures, sunlight and nutrient-rich waters that create a “bloom,” according to the state Department of Health.

Shellfish such as clams, mussels and oysters can become particularly affected by the biotoxins because they are filter feeders, and the toxins can accumulate in their flesh. The biotoxins are not harmful to the shellfish themselves but can be dangerous for animals and humans if eaten. Cooking affected shellfish will not rid them of the toxins, and harvesters simply need to wait for biotoxin levels to return to lower levels.

Harvesters should check the state Department of Health shellfish safety map at bit.ly/2WtgeJh before grabbing a shovel.

Correction: A previous version of this story incorrectly stated which agency issued the shellfish closure. It has been corrected. We regret the error.