Monitoring work undertaken on behalf of the Food Standards Agency has identified raised levels of shellfish toxins in East and West Loch Roag - Linngeam, Torranish, Drovinish, Miavaig and Eilean Tenish in Lewis.
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 council is monitoring the situation and will remove warning notices when it improves.