Shellfish harvesting has been closed for Port Madison, Miller Bay and Port Orchard Passage.
Tests show high levels of marine biotoxin paralytic shellfish poison.
The closure includes all inlets and bays from Agate Pass Bridge to Illahee State Park.
An earlier closure on Bainbridge Island was on the eastern shoreline from Point Monroe to Restoration Point.
The ban is for all species of clams, oysters and mussels. Shrimp and crab are not included.
Symptoms include tingling around mouth, appendages, loss of control of arms and legs, difficulty breathing; and chest can become paralyzed leading to suffocation and death, the Kitsap Public Health District reports.
Toxin levels are at 133 micrograms per 100 grams of shellfish tissue in the BI closure. For this more recent one, it was 91. Harvests are closed at 80 micrograms.