The public have been advised not to eat shellfish from the East and West Loch Roag areas.
Monitoring work undertaken on behalf of Food Standards Scotland has identified raised levels of shellfish toxins in East and West Loch Roag.
The Comhairle say: "Eating shellfish such as mussels, cockles, or razor fish from these areas may pose a risk to human health and notices to warn the public and casual gatherers have been posted at various locations on the shore."
Commercial shellfish harvesters in these areas have been contacted by the Comhairle and steps taken to postpone harvesting until algae levels subside.
It is a sensible precaution to avoid eating shellfish from these areas until further notice.
The Comhairle is monitoring the situation and will remove warning notices when it improves.