Established in 2019, the Fort Foster SeagrassNet site is a coastal, subtidal, eelgrass bed at the mouth of the Piscataqua River in Portsmouth Harbor. It replaces the previous Fishing Island SeagrassNet site (NH9.1) established in 2001, which has not had eelgrass since 2006. Density and biomass of the eelgrass are often multiple times higher than those found in the inner Great Bay SeagrassNet site (NH9.2).