Commercial shellfish harvesting has ceased in certain bays along the west and southwest coasts, after high levels of toxins were found during routine monitoring.
As a result, the public are being urged to only consume shellfish from reputable dealers.
The high toxin levels in question are common at this time of year, due to the presence of a microscopic plankton species in Irish waters.
In some instances, consumption can lead to paralytic shellfish poisoning.
In extreme cases, this can lead to muscle paralysis, respiratory failure and even death.