Shellfish harvesting is closed in the Atlantic off the New Hampshire coast due to an algal bloom known as a “red tide.” This naturally occurring algae, known as Alexandrium, typically blooms in late spring and early summer, and can turn water a red color. However, the algae cause toxins to build up in shellfish that can lead to a life-threatening illness called Paralytic Shellfish Poisoning when consumed. Cooking shellfish does not reduce the risk of getting PSP. Red tides are extensively monitored by New Hampshire’s Department of Environmental Services. It is still safe to buy shellfish or harvest from an areas currently open to shellfishing – like the Great Bay.