CONCORD, N.H. – The red tide has hit New Hampshire’s seacoast.

State officials say shellfish cannot be harvested from the state’s coastal waters until further notice. Testing has found elevated levels of the paralytic shellfish poison known as “red tide” in blue mussels collected from the Isles of Shoals and Hampton-Seabrook Harbor.

The Department of Environmental Services says it is too soon to know how severe the red tide bloom will be or how long it might last.

Harvesting areas along the shoreline have been closed since June 7 because of high bacteria levels after heavy rainfall. Since then, an offshore bloom of the marine algae that causes red tide began to affect the area.

Red tide is a condition in which shellfish such as clams, oysters and mussels accumulate a potent toxin produced by algae. Eating the toxin can kill people.