Raised levels of shellfish toxins have found in Caolas Èirisgeigh (Kyles of Eriskay).
Eating shellfish such as cockles, mussels or razor fish from these areas may pose a risk to human health, warns the council.
Commercial shellfish harvesters in these areas have been contacted by the Comhairle and steps taken to postpone harvesting until algae levels subside.
A council spokesman said: "It is a sensible precaution to avoid eating shellfish from these areas until further notice.
"The council is monitoring the situation and will inform the public when the situation improves."
Shellfish health warning for island shoreline
16 June 2016