Oyster fishing in the Solent has been suspended, following the discovery of toxic algae during a routine safety test.
The ban will remain in place until the end of the season
Diarrhetic shellfish poisoning (DSP) has been found in oysters in the Western Solent.
Southampton City Council and the New Forest District Council have jointly issued an order prohibiting the collection of oysters from the area for 28 days.
If eaten, DSP can take effect in about 30 minutes, causing vomiting, diarrhoea, abdominal pains and chills which can last up to three days.
The ban affects an area including Lepe, Beaulieu River, East Sowley, Sowley, Lymington River, Lymington Bank, Pennington Bank and Keyhaven River.
Environmental health officers have advised fishermen who fished oysters in the areas after 3 March to have them tested for the algae or to return them to the water.
DSP is caused by naturally-occurring algal blooms which move with the tidal currents.
The ban is expected to remain in place beyond the end of the oyster fishing season on 21 March.