Scientists have known for many years that the phytoplankton Alexandrium fundyense is the cause of the harmful algae blooms that occur to varying severity each spring and summer along the coastal Gulf of Maine, sometimes extending as far south as Cape Cod and the adjacent islands, and in Georges Bank. In 1990, an Alexandrium bloom caused the closure of Georges Bank to harvest of surf clams and ocean quahogs, after fishermen were sickened from eating shellfish.