Conducted by a committee of Canadian and US government and university scientists, Gulfwatch examines the effects of decades of development and industrialization on the water quality of the Gulf as it relates to human health as well as its impact on other marine organisms. Gulfwatch scientists collect blue mussels at over 60 US and Canadian sites Gulf-wide, and analyze the organisms tissue for potentially harmful levels and concentrations of toxins including heavy metals, chlorinated pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). New Hampshire increased the number of Gulfwatch sampling locations from two sites per year in 1997 to an average of five sites per year from 1998-2005. The increased spatial coverage provides comprehensive information for contaminant concentrations throughout the New Hampshire estuarine waters.